- Processing Methods to Reduce Trans Fats
- Fractionation of Tropical Oils
- Modified Hydrogenation for Trans Fat Reduction
- Blending as Zero Trans Options
- Trait Modified Oils as Trans Fat Replacements
- Trans Free Frying Fats/Deep Fat Frying
- Pan and Grill Shortenings
- Case Studies Trans Reformulation in Fast Food Chains and Laboratory Frying (trait modified oils)
- Bakery Shortenings and Applications of Liquid Oils in Baking
- Liquid Oil/Monoglyceride/Diglycerides, Oleogels in Baking Shortening Applications for Trans Reduction
- Liquid Oil Applications in Cookies, Baked Snack Crackers, Spray Oils, Liquid Shortenings, Pan Release Agents, Pretzels, Muffins, Tortillas
- Trait Modified Oils in Fluid Shortenings
- Palm Based Baking Shortenings
- Trouble Shooting Trans Free Baking
- Bakery Margarines
- Retail Trans free baking shortenings
- Liquid oil (unhydrogenated zero trans) as Trans fat replacements in various food applications
- New technologies for Trans fat reduction in baking fats
- Trans Fat Replacements in Selected Products: A Review
- Technologies to Replace Trans Fats
- Applications of Trans Fat Replacements in Foods
- High Stability Frying Fats and Oils
- Algae Oils in food applications
- Baking Fats for Dough Structuring (Lamination)
- Zero Trans Options for Dairy Applications (Whipped toppings, Ice cream)
- Pizza Crusts (Trans free options)
- Confectionary Fats and Coatings
- Suitability of beta shortening as a frying fat/pan griddle oil/food service/Lamination in dough products
- Structured Emulsions and Edible Oleogels as Solutions to Trans Fat
- Introduction and recent progress in regards to Trans fat reduction
- Effect of specific fatty acids on our cardiovascular health
- Structured emulsions using monoglycerides
- Waxes and wax organogels
- Oleogels made using 12-hydroxystearic acid
- Ethylcellulose (Polymer) Oleogels
- Production considerations of ethylcellulose oleogels
- Using oleogels for neutraceutical delivery or encapsulation
- Phytosterol-oryzanol mixtures for oraganogelation purposes
Trans fat labeling became law in July 2003 (Anon., 2003). Key provisions include the effective date for including trans fats as a separate line on nutrition labels was January 1, 2006. Another provision allows foods containing less than 0.5 grams trans fatty acids per serving can be labeled as zero. Many companies began reformulation of products well in advance of the set 2006 date. A recent report indicates that by 2005 many food groups were reformulated to a 0.5 gram zero trans claim and by 2012, the figure had been reduced to 0.2 grams including baked goods that were cited as high trans foods (Rahovsky et al., 2012). Although the food service industry is exempt from the 2003 ruling, many local and state governments have enacted or proposed the banning of trans fats in the public arena. Restaurants, hospitals, schools, fast food chains, and supermarket bakeries would be affected. Moreover, the FDA has proposed to remove trans fats from GRAS status which could possibly preclude the use of hydrogenated oils in foods. The 2003 rule impacted the hydrogenation industry as early as 2005 when catalyst sales dropped by about 50%. Moreover, many hydrogenation plants were either shut down or operating at reduced production. A plant in midwest US produced two million pounds of hydrogenated soybean oil per month before labeling, but production fell drastically to 20 thousand pounds in 2007.
Since soybean oil furnishes about 65% of domestic (US) edible oil usage and requires hydrogenation for stability and functionality, trans fat labeling has adversely impacted the soybean oil market. There has been a shift from heavily hydrogenated (up to 40 % trans) frying and baking fats to either liquid oil (1% trans) or lightly hydrogenated salad/cooking oils (10 to 11% trans)(List, 2013).
In the 1980’s and ‘90s food manufacturers were forced to cut saturated fats and to lower total fat due to strong concerns that saturated fat is a risk factor for coronary heart disease. Thus many food products were reformulated from tropical oils to hydrogenated oils by replacing saturates with trans (Norris and Gingras, 1990). During this period, palm oil usage fell dramatically. History has a strange way of repeating itself, however. Since trans fats have lost favor, Palm oil has resurged as a trans fat replacement. The US imported over 3 billion pounds of Palm/palm/ kernel oils in 2012, compared to 500 million pounds prior to trans fat labeling.
Technologies to Replace Trans Fats
Earlier on, food manufacturers had few options other than tropical oils and liquid commodity oils. However today the processing industry has responded with either new technologies or the adoption of older ones to bring zero trans products to the marketplace. Historically, interesterification is an old fat modification tool dating back to the 1920’s. By the late 1940’s and ‘50’s the method had been adopted by at least three companies to improve the baking properties of lard (Mattil and Nelson, 1953; Vander Wal and Van Akkeren,1951; Hawley and Holman, 1956). A detailed account is given by Slater (1953). Interesterification does not change the fatty acid composition or the iodine value. The process merely rearranges the position of the fatty acids across the glycerol backbone under high temperatures (70-100oC) such that the fatty acid composition approaches a random distribution. However the reaction can be carried out at low temperatures (directed) where the more unsaturated triglycerides crystallize out of the reaction medium (Eckey, 1948). The catalyst commonly used in random reactions is sodium methoxide while sodium metal has been employed in directed industrial practice (Holman and Going, 1959; Dijkstra, 1980).
In 2003 Archer Daniels Midland introduced enzymatically interesterified oils with the acronym “Nova lipids” (Anon. 2004).
The process consists of blending unhydrogenated liquid oils with completely hydrogenated soybean or cottonseed hard stocks and passing the heated mixture through a series of four reactors holding from 100-400 kg 1-3 specific enzyme per reactor. After the reaction is complete the oil can be used as is or blended with additional oil or hard stock. The physical properties of the interesterified oil can be controlled by the amount of hard stock in the simple blend. Random reactions with sodium methylate produces side products including colors, soaps, methyl esters and partial glycerides which must be removed by downstream processing such as inactivation of the catalyst, washing, and adsorbent bleaching before going to the deodorizer. A major advantage of the enzyme process stems from the fact that since no side products are formed no cleanup is needed and the rearranged fat can be fed directly to the deodorizer. The technology is considered “green”. The nova lipids serve as margarine/spread oils and baking shortenings and perform as well or better than hydrogenated oils in cookies, cakes, pie crusts and biscuits. Bunge Oil has also introduced baking shortenings based on enzyme technology (Dayton, 2013). They also are based on use of domestic crops.
Palm oil (100%) is an excellent all-purpose shortening but is high in saturated acids. A number of baking shortenings can be formulated from interesterified (30%) palm stearin (IV 44) and 70 % soybean oil or 100% of interesterified palm stearin. The former will contain less saturates. Puff pastry fats can be formulated from a number of fat blends containing soybean oil and beef fats, palm and hydrogenated palm, and soybean oil (Berger, 2010).
A number of soft and stick margarines can be formulated from liquid oils including palm olein, palm stearin, and palm oil. Tub products can be made with a blend of 20% liquid oil and 80% of an interesterified palm kernel 75/25 palm olein blend.
Palm olein is used as a frying fat in many parts of the world.
Food uses of Palm Kernel oil include margarines and spreads as a butter replacement in dairy products, filled milk powders (coffee whiteners, fully hydrogenated palm kernel oil), ice cream and cheese. Palm kernel oil is suitable for nut roasting, popping oil, and spray oil for cream crackers and sandwich cookies. As a spray oil, a shiny appearance appears which is attractive and a moisture barrier keeps the product crisp. Palm kernel oil is useful in dietary products where metabolic problems prevent digestion of ordinary C16-18 carbon acids.
Medium chain triglycerides (MCT) are made by fractionating palm kernel oil and then resynthesizing the shorter chain acids into triglycerides. Compositions of 80-90% (C10) and 10-20% (C8) are preferred.
The use of low iodine value base stocks for use in spreads and shortenings was investigated as well (List et al., 2007). Trans acid formation during hydrogenation of soybean oil under commercial conditions (high temperature, low pressure, nickel catalyst) reaches a maximum at iodine values of about 70 at which time trans double bonds begin to hydrogenate and stearic acid is formed. By continuing the reaction to IV of 40-45 trans bond are reduced and a mixture of trans and stearic triglycerides are formed. Thus functionality (solid fat content, melting point) can result from both trans and saturated triglycerides. Blending of the low oils with liquid oil resulted in low trans margarine and shortening oils. Jackson et al. (2008) extended the studies by a catalyst switching strategy where nickel was used to reduce the iodine value to 70 and then switching to a platinum catalyst to complete the reaction to lower Iodine values. These studies showed that even lower trans content can be achieved for margarine/shortening applications. The high cost of platinum and its recovery discourage commercial usage. However the low IV oils made with nickel have advantages. The temperatures and pressures are well within the limits of commercial hydrogenation equipment and the nickel catalyst is readily available on the open market. Two major producers of edible oils have introduced low trans products based on the above results (Cargill, ADM). The use of low temperatures, higher pressures with a phosphoric acid modified nickel catalyst form the basis of five patents for low trans oils (Van Toor, 2009, 2010; Higgens, 2007, 2013).
Applications of Trans Fat Replacements in Foods
Liquid unhydrogenated oils (both commodity and trait modified) can be used in many baking applications especially when emulsifiers and or surfactants are added to the oil (Hartnett and Thalheimer, 1979; Smith, 1979). At one time lard was the choice for the baking of bread. Today soybean oil containing an emulsifier/surfactant package is the standard liquid shortening for the bread industry. A number of popular baked snack crackers have been successfully reformulated with unhydrogenated soybean oil as the lipid portion (Klemann, 2005). These include Triscuits and Wheat thins, both of which are zero trans fat plus the Triscuits carry a heart healthy symbol on the package. Reduced fat Oreos were reformulated with a blend of canola and palm oil. The new cookies performed well in consumer tests. Other foods reformulated to zero trans with liquid unhydrogenated oils include pretzels (Manirath et al., 2006), tortillas (Gerardus et al., 2009) and muffins. Soft cookies require creaming which traditionally has been emulsified or unemulsified hydrogenated all-purpose shortening formulated from hydrogenated or animal fats having a short plastic range and high oxidative stability. Aini Idris et al. (1991) reported a baking study where soft dough cookies were prepared from palm oil, blends of palm oil and butter, and 100% butter and compared to a commercial cookie. Sensory tests indicated a preference for butter but the experimental cookies were softer in texture.
Hard cookies require fat for lubrication and any formulation calling for vegetable oil include both commodity and trait modified oils for a trans free solution. In commercial cookie baking, spread is a crucial factor affecting packaging since too much or too little spread affects the number of cookies per stock keeping unit. Several studies where hydrogenated fats were compared to trans free shortening have been reported with regard to spread in sugar cookies (Tiffany, 2008; McNeil, 2005). Trans free shortenings did not increase or decrease spread.
High Stability Frying Fats and Oils
Frying shortenings have evolved over the years from animal fat based products (Woerfel,1960) to plasticized (cubed) all hydrogenated vegetable oil, to fluid suspensions of hard fats in a partially hydrogenated base (usually soybean oil). Although never popular in home usage, the latter found wide acceptance in the food service sector because of low cost, excellent fry life, and ease of handling. As liquids they can be pumped into storage tanks at the point of use or in restaurants they can be purchased in 35 lb. jugs or 420 lb. drums. However trans fat nutrition labeling has changed everything. Animal based shortenings while popular with consumers are high in saturated acids and contain cholesterol which is a disadvantage where a friendly label is desired. The heavily hydrogenated cube products (IV 70) may contain up to 45% trans acids and the fluid products about half this value (20-25%).
Baking Overview/Functional Properties of Fats and Oils
Fats and oils serve a number of purposes during the baking operation, depending on the particular product. The classic study on the behavior of fats in baking was reported in 1944 (Carlin). Cake batters (layer/pound) appear to be suspensions of air bubbles distributed in a medium of liquid and flour. Little, if any, liquid appears to be emulsified in the fat phase. Soluble ingredients such as sugar and salt are dissolved in the water phase of the batter. Air spaces in cakes are invariably surrounded by fat. During baking the fat quickly melts and releases suspended air to the flour/water medium. Gas produced by the baking powder finds its way into air spaces already existing within the batter. Microscopic examination by polarized light indicates that the cross section of wheat starch disappear at this stage of baking. During baking a constant movement of air spaces follows a convection pattern until baking is nearly completed. At this stage, movement becomes violent and without direction. Carlin concluded that the use of monogylcerides as emulsifiers produces a finer dispersion of fat throughout the cake batter.
Thus, the functional roles of cake shortening include lubricity and aeration (creaming). In the mixing stage creaming is a function of the crystal form of the fat, emulsifier systems, and the levels of liquids and sugar that can be tolerated. Control of these factors is critical to the finished cake quality whose attributes include cake volume, grain/symmetry, moistness and storage life. Thus, creaming or the ability to incorporate air into baked goods is an important factor in the selection of cake shortening. Cake batters are prepared by mixing lipids, flour, water, sugar, and possibly emulsifiers and surfactants. Creaming is dependent on the crystal habit (beta prime) of the fat or oil, the composition of the emulsifier system, and the levels of sugar/liquids. In turn, finished cake quality (as measured by volume, grain, symmetry, moistness, and storage life) depends on the extent of creaming during the mixing stage.
Icing shortenings provide lubricity, structure and aeration. Body and texture is dependent on the creaming ability of the shortening. Emulsifiers/composition and sugar levels effect icing spreadability and stability. Lubricity (mouthfeel) at body temperatures is an important functional property of icings and is determined by the melting profile of the shortening and granulation of sugar. Icing shortenings are formulated with triglycerides with melting points at body temperatures. Overall lubricity effects are achieved from the combination of both cake and icing (Kincs, 1985).
Pie shortenings play a slightly different functional role in baking. Lubricity is dependent on the oil fraction being loosely bound in the flour. Dough should not be over mixed to prevent excessive absorption as this leads to tougher crusts and shrinkage. In commercial operations mixing is conducted at colder temperatures to control absorption. Thus, a pie shortening must be plastic at refrigerator temperature to ensure adequate rolling and forming. Lard has been a preferred pie shortening as flaky crusts are highly desirable. Lard has the proper composition, melting profile, and crystal habit needed for pie crusts. Unlike cake and icing shortenings, where the desired beta prime crystal habit is desired, lard is a beta tending fat leading to flaky textures.
Fats and oils function in baking through lubricity, which includes the shortening of gluten strands in flour and mouthfeel, and in turn, contributes to tenderness, and richness of the baked goods. Lubricity also can be applied to the ability of the oil to form an oily film which is viscosity related and how well the fat or oil melts in the mouth. Fats melting at body temperature tend to give a pleasant cooling effect whereas those melting above body temperature yield pasty or waxy sensations (Bessler and Orthoefer, 1983).
Liquid oils (unhydrogenated) are not suitable for commercial baking unless blended with emulsifiers and/or surfactants. However, technology developed over the past 40 years has contributed to a number of liquid shortenings, many of which are used in commercial baking operations. They perform well in breads, cakes, and other dough-based products. Liquid shortenings provide a trans free solution for baking and coupled with the fact that they are easily pumped, handled/stored and metered in baking operations provide additional advantages. Thus, liquid shortening based on trait modified oils and emulsifier/surfactants should perform well in many dough based baking applications especially where shelf life may be a prime consideration. A wide range of low fat foods including baked snack crackers, pretzels, tortillas, and pizza dough have been successfully reformulated to zero trans with liquid oils. A recent report indicates that cereals formulated with high oleic canola oil have increased shelf life (Lui and Issanvoa, 2012). Soft cookies are usually formulated with solid emulsified shortenings which may be high in trans. However, trait modified oils blended with hard stock and emulsifier/surfactants offer a trans free solution, along with needed solid fat.
Many all-purpose baking shortenings can be formulated from blends of hydrogenated soybean oil, liquid (unhydrogenated) oils and completely hydrogenated soybean or cottonseed oils (hard stocks IV<5). While highly functional, these products tend to have 20-25 % trans acids and are higher in saturates as well. A recent report indicates that a trans free option is available through blending hard stocks with trait modified high oleic canola oil or interesterification of the simple blends (Orthoefer, 2005).
In addition, most recent inventions were related to reduction of the saturates by utilization of cellulose fibers in conjunction with fully (less than 5 IV) or partially hydrogenated oil(s), or solid stearin fractions such as palm stearin, or other solids at room temperature esters or partial esters such as diglycerides, monoglycerides, waxes or mixtures of these in order to provide a crystal matrix and a liquid oil. Canola, high oleic canola, soybean, corn, or a semisolid oil such as palm oil, or a partially hydrogenated oil with solids at room temperature allow a plastic shortening-like material to be produced with reduced levels of both trans fatty acids and saturated fatty acids compared to a shortening formulated without the fibers.
The fibers aid in structuring the shortening, partly by taking some of the oil into capillaries and tying up some oil, wetting the fiber surfaces and, partly by physically acting to re-enforce the crystal structure formed by the higher melting fractions incorporated into the blend. The sum of trans plus saturated fatty acids in an all-purpose shortening formulated using partially hydrogenated oil and a heavily hydrogenated oil is about 50%. The sum of trans plus saturated fatty acids in a shortening formulated without use of hydrogenation is about 52%. The sum of trans plus saturated fatty acids in a shortening system formed by using a novel hydrogenated base stock and a fully hydrogenated oil has a trans plus saturate level of about 32%. The new approach allows trans fatty acids plus saturated fatty acid levels less than those mentioned above, since it allows the use of a shortening formulated to have lower solid fat content in the shortening. A comparison of the shortenings mentioned above and the oil system used most frequently in this work had a saturate plus trans fatty acid level of about 18.5% (Higgins, 2013).
Crisco shortening has been a household favorite for over a hundred years. Since 2003, the product has been reformulated several times to be trans free. Currently, Crisco contains hard stock and trait modified sunflower oil. It claims to perform as well as the older formulations.
A number of baking shortenings formulated from palm oil, palm kernel, trait modified high oleic canola and unhydrogenated soybean oil are available commercially. Typically, these products are used in industrial pie manufacture, in refrigerated and frozen dough and applications where a sharp melting point is required for mouthfeel. While low in trans acids these products tend to be high in saturated acids. Other baking shortenings (all-purpose) are available and are non-hydrogenated (zero trans) with different degrees of firmness ranging from very soft to very firm depending on the amount of palm/palm/kernel in the formulation. Saturates range from 18% (very soft) to 50 % (very firm).
Shortenings designed for puff pastry and other laminated dough can be formulated with palm oil and trait modified soybean oils. They provide excellent flakiness, structure, and lamination as well as optimum performance on automated dough lines. Blends of trait modified soybean and palm oils formulated with mono/diglycerides are highly suitable for breads and yeast-raised dough since they provide easy dough handling, less proofing time, plus less dusting flour is required.
Cake and cake mix shortenings can also be formulated from trait modified soybean and palm oils containing an emulsifier system composed of polyglycerol monoesters, mono/diglycerides and lecithin. These shortenings produce moist cakes with improved eating qualities, structure, volume, and freeze-thaw performance. By modifying the emulsifier system to include polysorbate 60 along with mono/diglyceride blends of trait modified soy/palm, the applications to cakes, icings dough, and tortillas is extended.
Performance of Trans Free Baking Shortenings
Protocols for the assessment of baking shortenings are given in the standard methods of the American Association of Cereal Chemists. They are designed to assess flour quality. The shortening is a hydrogenated vegetable oil based all-purpose component.
In commercial baking of cookies, spread is a prime consideration, since too much spread or too little affects packaging. The shortening must yield a uniform number of cookies (stock keeping units) per package. In addition, wicking or seepage of oil is undesirable.
A number of studies have been reported on the use of liquid oils for baking breads, cakes, and sweet dough products (Hartnett and Thalheimer,1979a,b). However, emulsifiers and surfactants are needed for optimum results. Bread baked with 3% soybean oil gave sticky dough that was difficult to handle. Incorporation of 0.5% monoglycerides/ polysorbates gave improved performance equal to that of standard liquid bread shortening with respect to dough handling, grain, and softness. Similar results were obtained in cake baking tests, except 8-12% polyglycerol monostearate (PGMS) emulsifier was required. Sweet dough made with only liquid oil handled poorly, was sticky and had low specific volume and open irregular grain. The addition of 2% monoglycerides gave only a slight improvement in dough handling. An emulsifier system of 1.5% monogylcerides/ polysorbate performed well in sweet dough.
Kamel (1992) evaluated the characteristics of breads and buns baked with liquid vegetable oils of different iodine values compared to the results of lard and palm oil. He concluded that soybean and canola oils containing emulsifiers gave baking performance equal to the solid fats with a reduction of 30% total fat. Baldwin et al. (1972) reviewed the uses of liquid oils in cakes and breads with added surfactants. These authors point out that the solid fat profiles of oil/surfactant and hydrogenated shortening are markedly different at the temperatures of 100° to 110°F (where leavening power occurs); however, the two systems gave comparable crumb softness and moisture retention.
Enzymatic interesterification of liquid oils with completely hydrogenated stearines offer a trans free solution for all-purpose baking applications, including sugar cookies, high ratio cakes, and pie crusts. These shortenings are available commercially. Studies comparing a hydrogenated, palm based against several interesterified shortenings showed that sugar cookies had comparable stack height, but the hydrogenated shortening had the smallest spread and force to break after three days. Wicking or seepage of oil was comparable and the spread factor (width/height) was very similar for all shortenings tested. High ratio cakes were evaluated for texture (grain), force to break, and height and batter specific gravity. The interesterified shortenings produced cakes with finer grain than the hydrogenated shortening. Small differences were observed in batter density but the interesterified shortenings gave the best cake volume height. Texture or peak force measurements made after one and three days showed that the interesterified shortenings were equal to the hydrogenated control, indicating equivalent cake softness. Evaluation of pie dough showed that interesterified shortenings gave the least amount of wicking and the lowest peak force required for breakage.
In summary, limited data indicate that interesterified baking shortenings perform in a wide variety of applications as well as, or better than, the hydrogenated fats they replace.
Troubleshooting Trans Free Baking Shortenings
A popular trans free option involved substitution of palm based shortenings for the hydrogenated product used previously. Thus, drop in solutions did not always yield equal results. However, many of the problems were overcome with adjustments to the baking process and the storage and handling of the replacement shortenings.
Common complaints were shortenings were too hard or soft, off flavors, and quality losses over time.
Problems: Creaming issues, off flavors, stiff dough, poor cookie texture/spread, poor icing performance/donuts.
Solutions: Palm oil based shortenings tend to be harder in winter and softer in summer leading to creaming issues. Since palm based shortenings are sensitive to temperature changes, to achieve the desired firmness in dough based goods, storage in warmer months is advised and conversely, cooler storage in summer months. Palm based shortenings can on rare occasions develop slight off flavors in sweet rolls and pound cakes. Switching brands or the addition of butter flavor to the recipe may be a solution. Some complaints that trans fat replacements have shorter storage life than the hydrogenated shortenings can be addressed by following the supplier’s storage instructions. While hydrogenated shortenings keep for one year, 6-9 months have been observed for trans replacements. The purchase of smaller quantities more frequently is another option.
Some bakeries pre-make the dough in advance of the next day’s needs, followed by resting in a cooler. As a result the dough becomes too stiff to work and roll out. Palm based all-purpose baking margarines are temperature sensitive. This problem can be resolved by allowing the dough to sit at room temperature long enough to become soft enough to work. However, dough should not be permitted to stand for more than 2 hours at ambient temperatures. Sugar cookies baked with trans replacements may become too crisp. This can be resolved by adjusting baking times or temperatures. Other solutions include replacement of sugar levels with (up to 25%) liquid sweeteners. However, liquid sweeteners may increase browning and require control of bake time and temperatures and sweetener content. Chocolate chip cookies may spread excessively with trans replacements. Solutions include increasing baking temperature 25 degrees higher than usual to “set” the cookies earlier in the baking cycle and then reducing baking time. Cookie spread can also be controlled by substituting some of the flour with 20% high gluten bread flour. Trans free icing shortenings may develop off flavors and colors. Switching brands may provide a solution. The day butter creams are made may be highly satisfactory when fresh, but after a day lost volume and oil could occur. These problems can be traced to improper emulsification of the shortening. Some all-purpose shortenings may not contain emulsifiers. All icing shortenings are emulsified but may not perform in the same way. Solutions include use of other brands, adding extra emulsifier (as directed by the supplier) or making smaller batches and using the same day. Icing problems include being too soft or too firm. Soft icings can be refrigerated before use while stiff icings can be tempered at room temperature for up to 2 hours. Adding up to 5% water can also be helpful. Over mixing icings may cause breakdown. Soft sandwich cookie fillings may require a longer set time before crowning. Trans free donut frying oils can lead to greasy and bitter tasting donuts. Switching brands or the use of fresh fat at the proper temperature are possible solutions. The past wisdom suggested that donuts should be fried in shortenings having high solid contents so that when the donut cools, the solidified fat allows icing and glazes to adhere and not break or slump off. However, it is claimed that quality donuts can be fried in trait modified canola oil with the products retaining excellent eating properties and icing/glaze adherence.
Manufacturers have introduced frying shortenings designed specifically for donuts. They are formulated with palm oil and trait modified oils and, as such, provide solids from the palm oil and increased fry life from the high oleic acid contents of the liquid component.
Several other potential applications of trait modified oils for baking include liquid shortenings employing trait modified oils in combination with emulsifier/surfactant systems (Skogerson, 2010; Doucet, 1999) or structured emulsions prepared by shearing monogylcerides, oil, and water. These products are easily made, contain low trans and saturates, and perform well in providing structure to a wide variety of baked goods including cookies, cakes, pie shells, biscuits, muffins, pizza, and frozen dough (Marangoni and Idziak, 2008).
In conclusion, trait modified oils offer a zero/low trans reduced saturate solution for many baking applications. In 2008, these oils supplied about 12% of domestic edible oil consumption. Today, about 18-20% of the edible oil market can be attributed to trait modified soy, canola and sunflower. As new oils are introduced, commercialized and supplied, the increased costs will decrease. Early efforts to expand the trait modified oil industry were hampered by the higher costs of grower premiums, identity preservation, and supply issues. Emphasis on health, nutrition, and obesity will continue to be a focal point for the food industry and the trait modified oil industry will play a major role in addressing these issues.
Fractionation of Tropical Oils as Trans Fat Replacements
Palm/palm kernel oils are the largest oilseed crops grown in the world. They have been proven to be a versatile trans fat replacement particularly where solid fat is needed for functionality. Palm oil consists of about 50% saturated acids, which after fractionation yields oleins and stearins and upon further fractionation super oleins and stearins result, giving added flexibility for fat formulations. Palm kernel oil is more saturated (90%), but unlike palm oil, the fatty acids are short chains which is advantageous in confections since they tend to be hard and rigid at ambient temperatures, yet melt rapidly at body temperature (Rossell et al., 1985).
Modified hydrogenation for trans fat reduction
Prior to 2003, catalytic hydrogenation was the preferred fat modification method in the US and other parts of the world. Reasons for this include:
- soybean oil is cheap and in abundant supply,
- the reaction is versatile salad/cooking oils, margarines/spreads, and
- baking shortenings can be made from just four oils (liquid oil, IV 80 oil, IV 65 oil and hard stock IV 5 or less).
Trans acids crystallize quickly and predictively. The latter is crucial in achieving smooth products with a uniform consistency. Palm oil has a tendency to crystalize slowly and products may become harder with storage.
Under conditions of commercial hydrogenation (i.e. high temperatures, low pressures, modest agitation, and nickel supported catalysts) 0.73% trans acids are produced with each drop in iodine value. So a 20 unit drop from 130 to 110 yields about 15% trans, a drop from 130 to 80 = 36.5 % trans and a drop from 130 to 65 = 47 % trans acids. The goal is to remove poly unsaturates without increasing saturates.
The fact that trans acid formation can be achieved by modifying the conditions of the reaction has been recognized for years, but only since trans acids have become crucial has the information been used to any great extent (Beers et al., 2008). In 1995 a report appeared on trans suppression, but increased catalyst loadings made the technology unattractive to the industry (Hasman, 1995). Research carried out by the USDA lab in Peoria, IL showed that hydrogenation of soybean in super critical carbon dioxide results in very low trans acid content at very high pressures (King et al., 2001). Although the reaction products contained very high melting triglycerides, the data suggested that a window of temperature and pressure exists where a nonselective reaction becomes selective (List et al., 2000).
Further work (Eller et al., 2005) confirmed that by lowering temperatures from 220oC to 140-170oC while increasing pressure from 30 psi to 200 psi, trans decreased by 56%. Blending studies with liquid soybean oil showed that spread oils meeting FDA labeling requirements (0.5 grams per serving) can be made with this technology.
Trait Modified Oils as Trans Replacements
Trait modification can be defined as changing the fatty acid composition of the oil by either traditional plant breeding and/or gene insertion techniques. Research began in the1960’s to remove linolenic acid from soybean oil due to its poor flavor and oxidative stability. Early work reported by Evans et al. (1965) showed that a reduction from the normal level of 8% to about 5% improved stability, but did not reach the targeted level of 3% achieved by hydrogenation. By the late 1980’s, Hammond et al. (1972) and Hammond (1984) succeeded in developing low linolenic acid soybeans and were commercialized by Kraft foods. An ARS scientist (Miller et al., 1987) discovered a way to regulate the fatty acid composition of sunflower oil and as a result, mid and high oleic sunflower oils were commercialized by ADM. But by the mid 1990’s sales of these oils were not profitable due to grower premiums and the costs of identity preservation throughout the seed processing streams (Krawczyk, 1999). Canola/rapeseed oil was introduced and commercialized in Canada in the late 1980-1990 time frame (Daun, 2011). The major lines are low linolenic canola and high oleic canola. Canola offers a trans free solution for food use as well as a low saturated acid content (DeBonte et al., 1999).
At that time the commercialized trait modified oil market was small, primarily because food companies refused to pay higher prices compared to lower priced commodity oils. Trans fat labeling has dramatically changed the picture. By 2008 trait modified oils furnished about 12% of domestic needs and by 2012 the figure rose to 18 to 20 %. Canola (4,124 million pounds), soybean (1,000 million pounds) and sunflower oil (550 million pounds) respectively, are the major players in the trait modified oil arena. Other liquid oils serving as trans fat replacements include corn and cottonseed oil which are defined as naturally stable because they contain only traces of linolenic acid. Their combined usage in 2012 was 2,120 million pounds.
Currently several trait modified soybean oils are nearing commercialization. These have been produced by a combination of plant breeding and gene insertion technology developed by Monsanto. Vistive gold is a low saturate/high oleic oil and is designed for high stability frying. Studies have shown that a significant reduction in both saturated and trans acids can be achieved compared to a standard hydrogenated frying shortening.
Omega-3 fatty acids are becoming increasingly important dietary fats. Some 50 afflictions and diseases have been linked to essential fatty acid deficiencies in humans. Monsanto has developed a stearidonic acid/omega-3 enriched oil containing 34% omega-3 acids. This oil will find use in dietary supplements and functional foods (Wilkes, 2008).
Algae Oils in food applications
The term single cell oil (SCO) was coined by Ratledge (1974) as a means of easily identifying lipids produced by microorganisms that would be suitable for human consumption and also serve as alternatives to plant and animal sources. The designation has proven popular since single cell oil is widely searched on websites (Ratledge, 2013). Ratledge further points out the term was intended to denote the triacylglycerol fraction of the total cell lipid that would be equivalent to commercial plant and animal fats and oils. Currently the term is expanded to include all lipids in a cell including algal lipids some of which contain complex glycosylated and sulfur containing lipids. However, several bacteria can produce oils rich in triacylglycerol’s (most notably Rhodoccocus opacus). Commercial production is currently confined to fungi (both yeasts and filamentous) and algae. Algae are cultivated erotrophically rather than by photosynthesis. Thus far, eight SCO’s have been commercialized (most of which are high in omega 3 and 6 acids). Although highly desirable as a source of essential fatty acids for neutraceutical and functional food supplements, applications to replace commodity oils will be limited due to the rapid oxidation of polyunsaturated acids and associated flavor considerations. Moreover, even if this problem can be overcome, production comparable to a commodity vegetable oil refinery (tons/day) would be a nearly insurmountable task. However, if algae SCO can be developed possessing fatty acid compositions comparable to commodity oils (low saturate high oleic/linoleic), coupled with mass production of biomass, Algal may offer possibilities as commodity oil replacements (i.e. salad/cooking oils, spreads and shortenings).
Oleaginous yeasts are known to yield triglycerides having fatty acid compositions comparable to commodity oils, with yields of lipids ranging from 36 to 72% (Ratledge, 1997, 2013; Ratledge and Hopkins, 2006). Fungi produce less oil than yeasts (24 to 50%) but have suitable fatty acid profiles for edible use.
Currently Algae oils are of great interest as feedstock for biofuel production. They grow quickly, with high yields of oil (up to 5000 gallons per acre per year), consume carbon dioxide/release oxygen and do not compete with agriculture. Microalga biomass is a potential source of not only fuel but feed and food as well. A further advantage is algae can be grown in salt water and can also purify waste water. Algal oils may be a potential source of oleo chemical feedstock for plastics, lubricants, fertilizers and cosmetics. The algae oil industry is a great opportunity for job creation (estimated at 220,000 by 2020). However, a number of roadblocks may hinder the growth of the algae oil industry. They include:
- Growing of biomass in large ponds require sunlight
- Harvesting and processing of biomass
- Recovery of oil
- Oil processing and recovery of value added by products
- Preservation of bioactive components per modified refining, bleaching/
deodorization, inert gas blanketing
- Preservation of finished oil quality (encapsulation, packaging, antioxidants )
Ratledge (2013) has summarized the major problems with large scale algae cultivation as follows:
- costs of photobioreacters
- large amounts of carbon dioxide are needed (14 tons per ton of biomass)
- water issues (open algal ponds need to be located in warm desert climates where minimal rainfall occurs)
- evaporation (a major concern)
- behavior of algae during periods of darkness/winter cold weather, and
- contamination of open ponds
Solazyme Inc. has been a major player in the edible algal oil arena. They reportedly have developed a fermentation based process capable of rapidly producing large amounts of biomass. Typically a single species of algae is charged into a vat, along with lots of sugar. By controlling temperature and pressure the algae metabolizes the sugar into triglyceride oil.
Ratledge (2013) reviewed the current status and future prospects for microbial oils (single cell oils). From 1985 to 1990 commercially produced oil rich in gamma linoleic acid (GLA) was available in the UK and was considered useful in treatment of multiple sclerosis. This has now been discounted. Prior to 1985, evening primrose oil was the major source of GLA but was very expensive. Thus a cheaper source was needed. When the new GLA rich oil was marketed under the name Oil of Javanicus, price wars between the two rival products reduced profits, such that production was halted. Evening primrose continues to be sold in the UK as a dietary supplement for control of PMS in women. Other factors contributing to failure include low production rates (5 to 10 tons per year) and the introduction of borage oil which has higher contents of GLA.
In the late 1980’s and 1990’s time frame, a new company (Martek Inc., USA) began to explore the possibility of producing long chain polyunsaturated fatty acids via microorganisms with emphasis on EPA and DHA. The founder and chief scientist at Martek believed that a market for a DHA-only oil existed in the infant formula sector since there was considerable evidence that DHA was important in visual acuity and brain development in infants. After clinical trials were performed, the results were not as desired. However it was discovered that a combination of DHA and Arachidonic Acid (ARA) was optimum for infant dietary supplementation. A mixture of two volumes of ARA and one volume DHA proved to be the most effective in infant formulations and is now sold in 70 countries by 23 companies.
The commodity oils available in the US and Europe include soybean oil, cottonseed oil, corn oil, canola (rapeseed), peanut, olive, sunflower, palm/palm kernel oils. All are processed in similar ways including extraction with solvents and/or expellers, degumming, refining with either caustic soda or steam refining, bleaching with adsorbents, and finally deodorized under a vacuum at high temperature. Small amounts of trans acids (1 to 2%) are formed during bleaching and deodorization. However they result from the thermal isomerization of polyunsaturates and chemically are different from trans acids produced by catalytic industrial hydrogenation. They are not counted for labeling purposes. Only C18 trans monoenoic acids produced from industrial hydrogenation are counted in accordance with FDA rules.
Some of the advantages of switching from hydrogenated fats to liquid (low/zero trans) oils for heavy duty frying are:
- A zero trans low saturate option results (friendly nutrition label/ heart healthy)
- Ease of storage and handling (pourable)
- Limited studies indicate that trait modified soy, canola, sunflower oils perform well in laboratory tests and foods fried in them are equal to those fried in a heavy duty hydrogenated frying shortening (www.frytest.com, Erickson and Frey, 1994)
- In Europe frying fats need to be discarded when Total Polar Compounds (TPC) (oxidation products) reach 24%. Studies conducted at Texas A&M University showed that commercially available zero trans oils could be used up to 14 eight hour frying days with total polar compounds about one half of the European standard.
Disadvantages of Switching to Zero Trans Frying Fats
- Increased costs. The trait modified oils are more expensive than commodity oils. With the exception of soybean oil, commodity oils may be used for heavy duty frying but fry life may be shorter. Trait modified soy, canola, and sunflower oils sell for up to 90 cents per pound retail, whereas cottonseed and corn oil sell for 60 cents per pound. Thus large users have the option of increased cost per longer fry life or cheaper oils per shorter fry life. A regional US chain (1800 employees, 40 restaurants) reported that switching from hydrogenated soybean oil to high oleic canola oil added an additional cost of 2 dollars per 35 lbs of oil which translates to an additional 2 cents per serving of French fries.
- Although limited small scale studies indicate that trait modified oils exhibit good fry life some fast food users have found that fry life may be shorter and more variable ranging from 7 to 14 days. However, factors other than the oil composition can affect fry life (breaded foods, volume of fried foods, high moisture foods leading to hydrolysis, inexperienced operators, excessive temperatures during usage).
- Supply may be an issue for very large fast food chains wishing to standardize frying fats for all outlets.
- Testing trans fat replacements can be very expensive and time consuming. Frito Lay reformulated nearly 190 products in 46 plants at a cost of 25 million dollars. This required 7200 man hours, 240 analytical tests, and 24 consumer test studies (Eckel et al., 2007). A major national chain using 160 million pounds of oil per year tested 26 oils and blends for fry life and consumer acceptance and by 2004 had narrowed the choice to two oils that performed equally. A trait modified soybean oil (low linolenic) was selected for test marketing in eight restaurants in New York City with overwhelming positive results. The decision was made to supply 5500 stores. The company uses active filtration to polish the oil with magnesol which extends fry life and retains seasonings added to the food. They concluded that fry life was equal to the hydrogenated shortening it replaced (Miller, 2007).
Suppliers of Zero Trans Heavy Duty Frying Oils, Shortenings, Confectionary, Coating Fats
Bunge Oils North America (low linolenic soy, mid oleic soy, high oleic soy, donut frying oil)–also a complete line of baking shortenings/margarines, cake/icing, all-purpose, pies, cookies, fillings, roll-in margarine, puff pastry, laminated doughs, flaked. Most of the shortenings are formulated from palm and soybean oil or enzyme technology. (www.bunge.com)
- Cargill is a major supplier of high oleic Canola oil marketed under the Clear Valley brand name–they contain 65-80% oleic acid, 7% saturates, and have OSI values of from 15 to 26 hours (DeBonte et al., 2012). Cargill is also a major processor of palm oil as well as offering baking shortenings based on interesterification (Transend) or modified hydrogenation technology. Cargill also supplies edible lard and tallow (RumbaTM). Flavored grilling, sautéing and dipping sauces are marketed under the Ultima Premium brand and are available as buttery or garlic flavors. All are zero grams trans fat per serving. The Cargill line of baking fats (Clear Valley) includes an all-purpose, donut, and icing shortenings. Applications include biscuits, cakes, pie crusts, cookies, muffins, doughnuts, icing, tortillas, and pastries/sweet goods. (www.Cargill.com/products/food)
- Archer Daniels Midland offers a diverse portfolio of trans fat replacements including naturally stable (free of linolenic acid) corn, sunflower, cottonseed, and peanut oils, all of which can serve as heavy duty frying oils. Other zero/low trans products are available through custom blending of liquid and lightly hydrogenated oil. ADM and their affiliate Stratus foods offer baking shortenings based on enzyme technology. Confectionary fats, cocoa butter replacements and coating fats are available based on palm/palm kernel oils. ADM is a major supplier of mid/high oleic sunflower (Nusun) and hydrogenated coconut oil. (www.adm.com/products and www.stratasfoods.com)
- Loders Kroklaan–Loders specializes in palm oil based products. The Sanstrans lines include frying fats and oils, and emulsified baking shortenings. The Freedom line consists of coating fats for all bakery products (flexible, melting point 43oC), a firm hard coating fat for baked goods and snack bars (melting point 43oC) and a flexible coating fat where rapid crystallization is desired. A palm kernel based hard fat for snack bars and confections is also available. (www.croklaan.com)
- AA Karlshams is a global company specializing in confectionary fats including cocoa butter equivalents, (ILLEXAO) substitutes (CEBES and SILKO) and replacers (AKOPOL). The equivalents are similar in composition and properties to cocoa butter. The substitutes are lauric based and are used in non-temper chocolate compounds. The replacers are primarily non lauric fats capable of tolerating moderate levels of cocoa butter (offering formulation flexibility). ILLEXAO ER is designed for cocoa rich dark chocolates. Replacing 5% of the cocoa butter results in a smooth creamy product and have excellent meltdown and flavor release. ILLEXAO BR and HS are designed to tackle the major issues of fluctuating temperatures and fat migration. BR improves bloom stability and makes it highly desirable for chocolates with soft fillings or a high content of hazelnuts. HS is a heat stable solution designed to raise the melting point of chocolate marketed in warm climates. The chocolate is firmer maintaining the right snap desired by consumers. HS performs well in chocolate high in milk fat.
CEBES MC and SILKO are cocoa butter substitutes designed for biscuit/wafer, and molded products. CEBES is a lauric based fat needing no tempering, has high bloom resistance and products are hard/glossy, stable at room temperature and non-greasy to the touch. SILKO provides coatings with fast crystallization and melt down properties.
CEBES NH/CEBES LS are also lauric based cocoa butter substitutes aimed at health benefits owing to the lack of trans fatty acids and reduced saturates. Advantages are a clean label (no hydrogenation), a healthy profile, and excellent sensory properties, fast crystallization in compound coatings and hard fillings.
AKOPOL MC/AKOPOL CO are cocoa butter replacements for coatings. Advantages include resistance to cracking and fat migration from cakes or pastries. Both have good bloom stability and excellent crystallization rates, and require no tempering leading to high capacity output on production lines.
AKOPOL NH/AKOPOL LT are cocoa butter replacements aimed at reduction or elimination of trans fatty acids and are partially compatible with cocoa butter. AKOPOL NH is trans free while AKOPOL LT has a reduced trans fat content. (See www.aak.com)
- Aarhus United USA markets zero trans reduced saturate margarine and baking shortenings (EsSence) based on a hard stock and liquid oil. Four oils with melting points ranging from 94-99, 99-104,106-112 and 108-114 are available for a wide range of baking applications. The Cisao line is based on palm or palm kernel oil and offers a wide range of melting points and solid fat contents. Applications include bakery shortenings, pastry and frying fats as well as filling fats, cream cookies and icings.
Baking Fats for Dough Structuring (Lamination)
Traditionally, laminated dough products have been formulated from animal or hydrogenated fats and oils blended to meet solid fat content (31-48 at 10oC, 11-31 at 21.1oC, 8-26 at 26.7oC, 2-11 at 33.3oC and 0-16 at 40oC) and melting point requirements (36-49oC). Table grade and table grade roll-in margarines (80% fat) have solid fat profiles and melting points very similar to butter (Johnson, 1999). Typically these products are high in trans and saturated acids as are roll-in and puff pastry margarines (total trans + saturates = 31%).
Trans fat labeling requirements have prompted the development of alternatives to hydrogenated baking shortenings. In 2002 Cargill marketed a zero trans shortening based on chemically interesterified canola oil and soybean hard stock. A year later ADM marketed the Nova lipid line of zero trans oils based on enzymatic interesterification of liquid soybean oil and or soybean, cottonseed hard stock (IV 5 or less) (Anon., 2004).
In 2002 Bunge Oils developed and marketed a line of zero/low trans baking shortenings based on modified hydrogenation technology (Higgens, 2007, 2013). However they were on the market for only a short time before being replaced with palm and soybean oils. Bunge’s zero trans solutions requiring non hydrogenated oils contains 10 baking emulsified margarines (NH 500 series) formulated from palm, soybean and canola oil. The puff pastry margarine (roll-in) is suitable for puff pastry and laminated dough products. Dropping point 121oF, solids at 10-40 as follows:
- 47 at 10oC
- 26 at 21.2oC
- 17 at 26.7oC,
- 11 at 33.3oC,
- 6 at 40oC.
Bunge also supplies a line of non-emulsified non hydrogenated (zero trans) based on palm and soybean oils, many of which are designed for specific products including pie crusts, icings/cream fillings, tortillas, and an anhydrous roll in shortening for puff pastry and other laminated doughs, a yeast raised dough shortening, and a flaked shortening (palm based) for an icing stabilizer, dry mixes, and biscuits. Other Bunge shortening include an interesterified soy/hard stock for use in very cold pie doughs as well as soy/palm based shortenings for industrial pie manufacture and refrigerated/frozen doughs (palm/high oleic) canola, and a palm kernel soybean based shortening where a sharp melting point is required (Tech. data sheets, Bunge Oils 2013).
Apparently some of the early zero trans shortenings did not perform like the hydrogenated products they were replacing. Users expected the new shortening to behave like the old one, but drop in solutions did not always yield comparable results. The American Institute of Baking conducted a study comparing a commercial palm based shortening (zero trans) against a hydrogenated control (Strouts, 2006). Products tested included cookies, pie crusts, puff pastry, cakes, and donuts. The palm based shortening performed as well, or better than, the hydrogenated control. A study in which interesterified (zero trans) was compared against a hydrogenated shortening with similar conclusions (Tiffany, 2008).
However in commercial baking a number of challenges were encountered, including differences in functionality (aeration changes, loss of volume, appearance change, greasy/oily handling, and interactions of the shortening with water in batters and doughs). Processing issues included achieving the desired specific gravity in batters and cream fillings, curdling of batter systems, and loss of sheet forming capability/disruption of dough film forming. Other challenges included finished product issues (reduction of shelf life, loss of softness in eating quality, and texture/crispness). Flavor differences (i.e. off flavors) were noted in high fat products (cookies, donuts) and eating quality that gives a coating effect from high melting triglycerides in the shortening (Strouts, 2006).
Many of the early problems with palm based zero trans baking shortenings can be overcome with adjustments to the baking process and/or storage and handling of the replacement shortenings. Palm based shortenings tend to be temperature sensitive and are harder in winter and softer in summer. As a consequence, doughs may not be workable or may bleed off oil. Thus storage conditions should be controlled. Some bakeries prepare and refrigerate the doughs before the next day’s production which can lead to poor machinability. Often this can be remedied by allowing the dough to set at room temperature for several hours.
The processing of palm based zero trans puff pastry margarine has been discussed in detail by Kirkeby (2008). A typical fat formulation is as follows: Palm stearin (50%), interesterified palm stearin/coconut oil (15%), palm oil (25%), and liquid oil (10%) (Kanagaratman et al., 2008). The fat has a solid fat profile of 50 at 10oC, 30 at 20oC, 21 at 30oC and 8 at 40oC which provides plasticity over the usage range of 20-25oC. The trans fatty acid content is less than 3%. Puff pastry margarine manufacture consists of sub processes including preparation of the aqueous and fat phase, emulsion preparation, pasteurization, chilling, crystallization/kneading, and packaging and tempering. The crystallization step consists of passage of the emulsion through a scraped surface heat exchanger (SSHE), followed by passage through a pin worker which breaks up the crystal structure, and finally to a second SSHE. Since palm oil crystallizes slowly it is desirable to allow the emulsion to rest in a tube before packaging. Optimum residence times in pin rotor and resting tubes as well as SSHE surface area requirements for a 1000 kg/hr plant is given by Kirkeby (2008). Mat Sahri and Aini Idris (2006) reported the effects of processing and polymorphic changes during storage of palm based margarine. Kirkeby (2008) recommends baking margarines be tempered for 5-7 days at temperatures between 18 and 23oC. Puff pastry is particularly sensitive to temperature changes during tempering. A few degrees can mean the difference between a good and a bad product. At low temperatures the plasticity may change to brittleness while at high temperatures becoming sticky. Puff pastry margarines containing palm stearin or interesterified blends are particularly sensitive to temperature. A common practice involved tempering at 23oC for several days followed by several weeks at 16-18oC.
The use of liquid (unhydrogenated) oils containing partial glycerides for trans reduction in baking shortenings is the subject of several patents (Doucet, 1999; Skogerson, 2010; Scavone, 1995). These systems allow a zero trans/reduced saturate composition. Applications include cakes, cookies, danish, icings, puff pastry and laminated products. They are powders containing 8% partial glycerides with a Mettler dropping point of 131-140oF. They are FDA GRAS approved for food use.
Corbion Caravan markets the Transcendim line of zero trans shortenings with applications in cakes, chemically leavened bake goods, cookie fillings, danish lamination, cookies, puff pastry, icing and frosting, roll-in shortening, tortillas, spray oil and donut frying. In many applications saturated acids are reduced from 33-50% (See www.corbion.com). Crystallization properties are reported to be excellent with the desired beta-prime crystal habit ensuring smooth products with good sensory properties.
The use of oleogels/structured emulsions to provide structure and functionality in baking applications is a recent technology (Marangoni and Garti, 2011). They are prepared by shearing monoglycerides, water, and common vegetable oils. The oleogels are zero trans fat replacements in a wide variety of food products including cookies, cakes, biscuits, pie shells, muffins, pizza, and frozen doughs (Marangoni and Idziak, 2008).
Low fat pastry has become popular. A recent study has shown that 60% puff pastry fat compares well to the traditional 80% products. The puff pastry shortening consisted of palm stearin (46%), palm oil (46%) and liquid oil (8%) with added lecithin (0.5%) and 2% distilled mono and diglycerides/polyglycerol esters of fatty acids. According to Palsgaard (Anon., 2011), the product had a plastic consistency and thus the margarine was very dry to the touch. Baking studies comparing 60 vs. 80% fat showed comparable height and expansion (Anon., 2011).
Zero Trans Options for Dairy Applications (Whipped toppings, Ice cream)
The incorporation of vegetable oils into whipped toppings and ice cream has been reported by scientists from Maylasia (Wan Rosani et al., 2008; Wan Rosani and Aini Idris, 2000; Berger, 1994). Palm Oil olein (POo) and palm oil stearin (POs) are suitable for whipped toppings when blended in the ratios of 85:15, 75:25, 65:35 (POo, POs). These blends have melting points close to that of dairy fat (32oC). A typical formulation for a whipped topping follows:
- Fat 25-40 %,
- Milk powder protein 1-4%
- Sucrose 10-12%
- Glucose syrup 3-5%
- Water 60-80%
- Emulsifier-stabilizer 0.3-1.6%
- Small amounts of flavor/color
The 85:15 blend showed emulsion stability comparable to dairy cream. Sensory evaluations showed that when compared to commercial toppings and dairy cream, the palm based toppings had better creaming properties. However, taste and odor scores were lower than the dairy products. While palm based toppings are trans fat free, they contain about 46% saturated acids (C12- C18) but are lower than dairy fat (58%).
Ice cream requires fats with bland flavors and good stability in the finished product as well as enough solid fat to be soft and stable at low temperatures yet melt at body temperature. Palm and palm kernel oils meet these requirements. Ice cream was formulated with the two oils and compared to milk fat. Sensory tests included appearance, flavor, body/texture, and melting property. The results showed that the palm based products were comparable to traditional dairy fat formulations. Palm oil is more suitable for hard ice cream because of its higher viscosity and hardness while palm kernel oil is more suited to softer products because of lower viscosity and sharply melting properties (Wan Rosani and Aini Idris, 2000).
Pizza Crusts (Trans free options)
Pizza crusts may be divided into three groups depending on whether they are formed by pressing, by sheeting and pressing (deep dish), or by hand shaping and tossing into a retail type pizza sold by pizza chains. The crusts are different in their properties and eating qualities and their formulations vary accordingly. Ranges of major ingredients include (flour weight basis) flour 100, water 55-70, salt 1-5, sugar 3-14, fat 3-14, yeast 0.5-5.0, or baking powder 0.5-4.0, calcium propionate 0.1-0.3. Fats may include plastic hydrogenated shortening (trans containing), a liquid shortening made with unhydrogenated liquid oil and emulsifiers and/or surfactants, or liquid unhydrogenated oil (soybean, cottonseed, olive oil). Olive oil added at 1-3% is preferred in many pizza recipes. However, it is expensive, therefore, a common practice is to blend one part olive oil with four parts canola oil. Development of self-rising crust pizza was a significant development in frozen pizza. The use of heat activated chemical leaveners provided additional aeration to crusts, thus allowing pizza to be eaten in the home.
A typical self-rising crust formulation is as follows: (Bakers Flour 100, salt 1.75, sugar 2.0, oil 5.0, leavening/yeast 1.75, water 50, hard fat flakes 8 (optional) (Lehmann, 1997). Oil used in the self-rising crusts would include unhydrogenated commodity or trait modified soy, canola and sunflower. All would be trans fat free.
Confectionary Fats and Coatings
Cocoa butter is an excellent confectionary fat since it has an ideal solid fat profile where it is hard at temperatures up to 20oC, yet melts very sharply at 33.3oC.
Cocoa butter is composed of three major triglycerides consisting of symmetrical isomers of palmitic, oleic and stearic acids. Over 80% of the triglyceride consists of POP, POS and SOS. (where P = Palmitic, O = oleic, and S = stearic). Because of their symmetrical structure these triglycerides melt very sharply at body temperature yet remain solid at ambient temperatures. However, the high cost and complex crystal structure which requires special processing (tempering) has prompted development of alternatives to cocoa butter for confections. The patent literature contains many examples of confectionary and coating fats based on interesterification, hydrogenation and fractionation of tropical oils (Cleenewerck, 2010, 2012; Sagi et al., 2013; Cain et al., 2000, 1995; Bennet et al., 1995; Tresser, 1984; Napolitano and Leas, 2004).
- Cocoa butter alternatives (CBA)–any fat which is used to replace cocoa butter,
- Cocoa butter compatible (CBC)–a fat that is compatible with cocoa butter and does not interact in adverse fashion,
- Cocoa butter equivalent (CBE)–a fat which is equivalent to cocoa butter in both chemical and physical properties and can be used in any proportion with cocoa butter,
- Cocoa butter extender (CBE)–a fat that extends or dilutes cocoa butter to make it more economical,
- Cocoa butter improver (CBI)–a fat which can improve the properties of chocolate/cocoa butter,
- Cocoa butter replacer (CBR)–a fat made from hydrogenated liquid oils which is inferior to CBS but has compatibility with cocoa butter,
- Cocoa butter substitute (CBS)–a fat made from palm kernel or coconut oils. (excellent physical properties but poor compatibility with cocoa butter),
- Hard butter–a fat which is used to replace cocoa butter (used primarily in North America) and is the same as cocoa butter alternative, (CBA).
Confectionary fats can be divided into three basic groups by chemistry: i) Symmetrical triglycerides, ii) High trans-hydrogenated/fractionated, and iii) Lauric type oils. The symmetrical types predominant in cocoa butter are POP, POS, SOS.
The high trans are mainly trans containing isomers of oleic acid and two saturated acids (PEP, SEE, EEE, SEP where E = elaidic, S = stearic, P = palmitic).
The lauric types are mainly trisaturated, containing a lauric (C12) or myristic acid (C14). (LLM, LPM, PPM where L = lauric, M = myristic).
Advantages and Disadvantages of CBE, CBR, CBS
Advantages: Compatible with cocoa butter, gives desired hardness, snap, mouth feel, improved heat resistance, stable consistency/ taste, no hydrogenation/trans acids
Disadvantages: Sophisticated tempering CBR (replacers)
Advantages: No tempering, taste stability, compatible with chocolate or cocoa
Disadvantages: post hardening/poor flavor release, hardness and snap inferior to cocoa butter, often hydrogenated/trans acids
Advantages: non temper, texture and melting close to cocoa butter
Disadvantages: recipe must be virtually free of cocoa butter, risk of soapy flavors and bloom, may be hydrogenated (trans acids)
|Physical Properties of Mixtures of Soybean Oil and Completely Hydrogenated Soybean Oil (SBOTS)
|SBOTS % liquid soy
||% SBOTS||Drop Point (°C)||SFC at 10°||SFC at 21.1°||SFC at 33.3°||SFC at 40°||SFC at 45°|
These data clearly show the virtual insolubility of completely hydrogenated soy bean oil up to 5% in liquid soybean oil over the range 10 to 45oC. Since confectionary fats must have a high steep SFC profile (i.e. high solids at 10 to 21.1oC, low solids at 26.7 to 33.3oC). Thus, the beta shortening described by Acvedo and Marangoni (2012), would be unsuitable as is. However, the fact that trans acids are absent and solids are present at low levels of hard stock, the beta shortening may be useful for formulations of confectionary fats as a component in other fat blends. For example, a blend of 8% SBOTS and 92% liquid soy shows a melting point of 52.7oC and solids ranging from 8.9% at 10oC to 4% at 50oC and as such, would furnish solid fat over the entire temperature range. Of course some lab work would be needed. It is suggested that a sample of commercial CBE and CBR be obtained mixed with the beta shortening (1 to 10%) and physical properties determined (i.e. Mettler drop points and SFC data). The goal would be to see how much beta shortening could replace other components in the confectionary fats without changing the properties of the fats. If possible, x-ray diffraction studies would be useful.
Suitability of beta shortening as a frying fat/pan griddle oil/food service /Lamination in dough products
Liquid shortenings have been used for many years in the food industry but have never been successful in the retail market. Proctor and Gamble test marketed a liquid household shortening under the brand of “Swirl”. Although a liquid that can be easily measured by volume and performs quite well, the product was pulled from distribution. On the other hand liquid shortenings have found wide acceptance by the baking industry. At one time lard was the preferred fat for bread. In the 1970’s liquid oils in combination with emulsifiers and surfactants became the industry standard for bread, rolls, cakes, and biscuits (Hartnett and Thalheimer, 1979).
Deep fat frying requires a fat to be oxidatively stable at high temperatures. Traditionally hydrogenated solid frying shortenings (IV 70) were the industry standard up until the mid 1990’s when health concerns over dietary fatty acids prompted the introduction of opaque liquid frying fats. Typically these products are made by hydrogenation of soybean oil to an Iodine value of about 100. The base is then blended with completely hardened soybean oil and allowed to crystallize in the beta form and stable suspensions. In essence the trans acid content of cube shortening was reduced from approximately 40 to 20%. With the advent of trans fat labeling in 2006, both cube and opaque frying shortenings have shown declines in usage.
To replicate the performance of hydrogenated products, without question the replacement of trans fats in baking applications has been the most difficult. The old trans containing shortenings crystallized quickly during manufacture (which was predictable). Moreover their physical properties (melting point, solid fat profile) served as a guide to their formulation with uniformity. However, palm based shortenings behaved differently during manufacture. Although a beta prime crystal former, palm based shortenings may change to a beta form with textural and performance issues. Palm oil contains a significant amount of the triglyceride POP which crystalizes very slowly. In effect, post hardening may occur. Products have the desired texture soon after processing, but upon storage they may be harder. The post hardening problem may be partly overcome by interesterification. A limited amount of research suggests that processing and tempering are crucial to the manufacture of palm based baking shortenings. Typically several A units (scraped surface heat exchangers) coupled with a B unit (pin worker) are employed along with a resting tube. Tempering must be done at the proper temperature for a given time frame. Puff pastry margarines (based on interesterified components) are particularly sensitive to textual changes during tempering and require longer times at lower temperatures (Kirkeby, 2009).
Some of the early problems with palm based baking shortenings included not only manufacture but performance in end uses as well. A drop in solutions did not always prove satisfactory (Loh, 2006). Merely substituting a zero trans shortening for a hydrogenated one often gave different results. Part of the problem rests with the limited number of baking tests available to suppliers, and furthermore, are designed to test flour rather than shortening in which a standard hydrogenated product is held constant for cookies, cakes, pie crusts, and biscuits. Thus while performing well in standard baking applications in the laboratory, the wide variety of industrial recipes and products were not always successful.
Applications of the Acvedo and Marangoni (2012) technology for laminated dough products (puff pastry danish) offer great promise for the following reasons:
- the lipid components are cheap and readily available
- the products are trans fat free
- no partially hydrogenated fats
- no interesterification
- the technology is flexible and the physical properties can be controlled by changing the lipid components (as such tailor made shortenings can be made for other applications)
- performance in food products has been verified
- technology needed for manufacture of the shortening is well established and no special equipment is required, Standard A and B units are sufficient for
- crystallizing and working the fat.
Though many promising solutions to trans fatty acids have been proposed and are currently in use, development is still required to ensure that we are not just simply substituting trans fats with something that is equally, or similarly harmful. We should attempt to develop solutions that not only provide all the requirements of a viable substitute, but also ideally contain components or ingredients that actually improve our cardiovascular health, such as phytosterols or polyunsaturated fatty acids. With the development of many functional and comparatively healthy replacements over the past five years such as oleogels and structured emulsions using monoglycerides, it is possible that we may be able to overcome the trans fat problem in the near future.
Introduction and recent progress in regards to trans fat reduction
Trans fatty acids were created and used by industries to fill a demand for functional fats that were solid at room temperature, and could withstand the oxidation stresses provided by temperatures in excess of 160oC when frying (Kodali, 2005). By simply changing the configuration of an unsaturation from cis to trans, a greater ease of packing can be achieved, due to more symmetrical molecules (Kodali, 2005). This creates a corresponding increase in the melting points of these fatty acids, and increases their stability when subjected to high temperatures (Kodali, 2005). When greater functionality was combined with what were believed to be health improvements over saturated fat, the widespread use of trans fats seemed to be ensured. Many years later, the shocking truth about trans fat and its deleterious effects on cardiovascular disease were reported (Mensink and Katan, 1990; Willet et al., 1993; Judd et al., 1994). In 2006, mandatory labeling of trans fatty acids became a requirement in the United States, in an attempt to force producers to reformulate products, and reduce our consumption of these harmful fatty acids (U.S. Food and Drug Administration, 2012).
In December 2009, Health Canada released its final monitoring report which reported the level of trans fatty acids in certain Canadian foods, including French fries, desserts, cookies, frozen appetizers, popcorn and snacks, and chicken products (Health Canada, 2012). The results were rather shocking, with only four of the 21 different product types tested meeting the required trans fat level. Only 40% of cookies from small and medium-sized family and quick service restaurants met the requirements, while only 25% of margarines from cafeterias located in institutions met the trans requirements. Though 18 of the 21 categories had 50% or more of the tested products meet the necessary requirements, trans fats clearly remain a problem (Health Canada, 2012). It is possible that for many of these products the producers were unable to effectively replace trans fats with a substitute, either due to lack of availability, poor functionality on the substitute’s part, or cost.
The small change in unsaturated fatty acid bond configuration from cis to trans has represented a large problem to the food industry with regards to its replacement. This created a great challenge for both academic and industrial scientists: provide a solid-like structure similar to highly saturated or trans-containing triacylglycerols, keeping functionality, yet without sacrificing human health. Other additional factors such as cost, availability, versatility, efficiency, and food grade status should also be considered when trying to find a replacement for trans fats (Co and Marangoni, 2012). A distinction can be made here; replacements that fulfill only some of these requirements should be considered as ‘substitutes’, while those that fulfill all of these requirements, and potentially provide additional benefits, can be deemed ‘solutions’ to trans fats. Many previously proposed substitutes for trans fatty acids have found their way into our diets; however, their effectiveness as a solution to the issue can now be seen, well over 5 years after January 1, 2006, which was when the new labeling requirements were put into place (U.S. Food and Drug Administration, 2012). This chapter focuses on structured emulsions and edible oleogels, two potential solutions to the trans fat dilemma. To understand why these are potential solutions, however, background information in regards to how specific fatty acids affect our cardiovascular health is required.
Effect of specific fatty acids on our cardiovascular health
Cardiovascular disease (CVD) continues to be the number 1 cause of death and disability in the world, resulting in an estimated 17.3 million deaths in 2008, and a predicted 23.6 million deaths in 2030 (WHO 2012). Blood serum cholesterol levels have been used for many years and an indicator for cardiovascular health, as a strong correlation was seen between high total serum cholesterol levels and CVD (LaRosa et al., 1990; Klag et al., 1993). Today, many different types of serum cholesterol have been identified, including the following: high-density lipoprotein (HDL), low-density lipoprotein (LDL), intermediate-density lipoprotein, very-low-density lipoprotein, and chylomicrons (LaRosa et al., 1990; Nordestgaard and Tybjærg-Hansen, 1992). Of these different types of lipoprotein, LDL and HDL are by far the most utilized to report effects on cardiovascular health, with increased LDL levels having a negative effect, and increased HDL levels having a positive effect on cardiovascular health compared to baseline levels (LaRosa et al., 1990). Typically, serum cholesterol levels are measured after the consumption of meals or diets containing a specific amount and type of fat or fatty acid. These levels are then compared to a control meal or diet, which is often carbohydrates or one specific fatty acid, such as oleic acid. The work of Mensink and Katan in 1990 was one such study that used oleic acid in their control diet, providing 10% of the subject’s daily energy (Mensink and Katan, 1990).
Though many studies in the 1990’s looked only at total changes in serum cholesterol levels, or change in LDL, it has since been shown that it is much more advantageous to report both the change in LDL and HDL, or more specifically, as a cholesterol ratio, ΔTotal:HDL (Mensink et al., 2003). With a ratio, it is very clear what specifically increased, and whether this indicates a negative, neutral, or positive effect on CVD. The work of Mensink et al., in 2003 showed cis polyunsaturated fatty acids had the greatest positive effect on CDV, with a ΔTotal:HDL ratio of approximately -0.032, while trans fatty acids showed the worst effect, resulting in a ratio of just over +0.02 (Mensink et al., 2003). Saturated fatty acids showed a fairly neutral effect on the ΔTotal:HDL cholesterol ratio, while cis monounsaturated fatty acids showed a ratio of -0.026, also indicating a positive effect on cardiovascular health (Mensink et al., 2003).
Trans fatty acids are considered the most deleterious type of fatty acids predominately due to their effect on this cholesterol ratio. While trans fatty acids caused the greatest increase in LDL levels, it was also the only type of fatty acid to decrease HDL levels (Mensink et al. 2003). This has been confirmed by many other groups, including Mozaffarian and Clarke in 2009 (Mozaffarian and Clarke, 2009). This group also showed impact on the ΔTotal:HDL ratio if trans fatty acids replaced poly, mono, or saturated fatty acids, on a basis of percent of calories replaced by trans fat (Mozaffarian and Clarke, 2009). At the level of 1% replacement of calories, the values are very similar to the +0.02 reported by Mensink et al. in 2003. However; when trans fat replaces 5% of calories formerly provided by polyunsaturated fatty acids, this value jumps to above 0.3, more than a tenfold increase (Mozaffarian and Clarke, 2009). When trans fat replaced 5% of calories from monounsaturated and saturated fat, the ratios were approximately 0.27 and 0.17 respectively (Mozaffarian and Clarke, 2009).
As with cholesterol, the general term ‘saturated fat’ can be broken down into specific fatty acids, with two of the most heavily studied being palmitic acid (C16) and stearic acid (C18). The effect of these fatty acids on serum cholesterol has been shown to be significantly different, and they should not be grouped together (Mensink et al., 2003). Stearic acid, which has been estimated to make up 3% of daily energy in the average American diet, has a slightly beneficial effect on serum cholesterol levels, with a ratio of -0.013 in the 2003 Mensink et al. study (Hunter et al., 2010; Mensink et al., 2003). Palmitic acid on the other hand, shows a more negative effect on cardiovascular health, with a ΔTotal:HDL ratio of +0.005, and was the most atherogenic saturated fatty acid studied (ΔTotal:HDL). This is troubling as palmitic acid is the most heavily consumed saturated fatty acid in the United States, with 56.3% of total saturated fat intake, resulting in 1.8-4.4% of daily energy for 14 European countries (Hunter et al., 2010).
Recently the true effect of saturated fatty acids on human health has come under debate (Siri-Tarino et al., 2010a; Siri-Tarino et al., 2010b). Contrary to what serum cholesterol values may indicate, a meta-analysis study covering close to 350,000 subjects found no relationship between saturated fat consumption and increased risk of stroke or CVD (Siri-Tarino et al., 2010a). Though saturated fat may not be as damaging to health as once previously believed, it can still be concluded that they, individually or as a whole, do not have the same positive benefits that mono and especially polyunsaturated fatty acids possess. When replacing 1% of energy formerly held by stearic acid with mono or polyunsaturated fatty acids, ΔTotal:HDL cholesterol can be lowered by 0.043 and 0.055 respectively (Hunter et al., 2010). An overwhelming amount of evidence has shown that polyunsaturated fatty acids possess the greatest cholesterol lowering effects of all other types of fatty acids (Mensink et al., 2003; Hunter et al., 2010; Kris-Etherton et al., 2004). Many oils from vegetable sources contain a high percentage of polyunsaturates, as shown in Table 1. For the development of any solutions to trans fat, the inclusion of a high level of polyunsaturates should be a priority, while minimizing the level of saturated fat.
Structured emulsions using monoglycerides
Emulsions consist of at least two immiscible phases, with one phase being dispersed in the other as tiny droplets (McClements, 2010). The most common type of emulsion is oil-in-water (O/W), with some examples including milk, cream, and mayonnaise (McClements, 2010). It can be a challenge trying to differentiate between a structured emulsion, and a simple O/W or water-in-oil emulsion, as often they involve much of the same ingredients and production procedures. For example, both commonly rely on a mixing or homogenization step to disperse one phase into the other, while they also both commonly use a minute amount of emulsifier to help stabilize the emulsion (McClements, 2010). Traditional emulsions are prone to physical instability (coalescence and phase separation), and are not able to provide a solid-like texture that is similar to hard-stock triacylglycerol molecules (McClements, 2010). While mayonnaise certainly has structure, it is unlikely that it would ever be described as looking ‘shortening-like’. With structured emulsions, products with a wide variety of textures can be created, including something that is similar to a traditional partially hydrogenated shortening (Zetzl and Marangoni, 2011; Batte et al., 2007a). Several varieties of structured emulsions have been listed in a review by McClements in 2010 and include the following: multiple emulsions, solid lipid particles, filled hydrogel particles, and multilayer emulsions (McClements, 2010). Here the focus will be on one variety of multilayer emulsions, as described by Marangoni in 2007, which use monoglycerides to entrap multilayers of water around oil droplets (Marangoni et al., 2007; Marangoni, 2007).
To understand more about this system, it is first important to describe how this type of emulsion is produced. The system can be created by first heating a co-surfactant–saturated monoglyceride-oil mixture above the Kraft temperature of the monoglycerides, until they have become fully dissolved in the oil. This mixture is then added to water while briefly exposing the system to a gentle external shear field. This leads to the formation of a multilayer lamellar monoglyceride structure in the liquid crystalline state, which surrounds the oil droplets. Upon cooling below the Kraft temperature, the monoglycerides undergo a liquid-crystalline to crystalline phase transition and adopt a solid-like structure (Batte et al., 2007a,b). The final product contains vegetable oil ‘droplets’, surrounded by the hydrated, saturated, monoglyceride multilayers (Zetzl and Marangoni, 2011; Batte et al., 2007a; Marangoni et al., 2008). These droplets can be easily observed when using freeze fracture cryo-scanning electron microscopy. By making adjustments regarding the charged co-surfactant ratio and/or pH, a semisolid material of high viscosity, similar to a shortening in appearance, can be formed (Batte et al., 2007a). Structured emulsions such as those mentioned here are already available commercially. One such product has been trademarked under the name Coasun™. This shortening-like material contains no trans fatty acids, limited saturated fatty acids, and is 30-40% structured water (Zetzl and Marangoni, 2011).
The structure from the term ‘structured emulsion’ comes from the monoglycerides, which are only incorporated at a level of a few percent, yet are able to stabilize the emulsion, greatly reducing phase separation, while at the same time providing structure. In fact, the monoglycerides could potentially be the only actual solid component in these structured emulsions at room temperature. This structure can be seen when analyzing X-ray diffraction spectra in the small angle region, where the structured emulsion (4.5% monoglyceride and 35% water) will show diffraction peaks (001, 003, 005, 007), yet mayonnaise will not. These peaks, which signify sizes of approximately 61 Å, 18 Å, 13 Å, and 8 Å for 001, 003, 005, and 007 respectively, indicate that there is a lamellar crystalline structure in the long spacing which is not shown by a traditional O/W emulsion such as mayonnaise. Three definitive peaks were also noted in the wide angle region for the structured emulsion sample, whereas the mayonnaise emulsion showed no definitive peaks. Peaks in this region signify that there is subcell packing; specifically, the peaks indicate that the sample had converted from the metastable α-form to the more stable β-form.
Rheology can also be used to show the difference between an O/W emulsion (mayonnaise) and a structured emulsion (Coasun™). When analyzing the storage modulus (G’) for the two different types of emulsions, at 10 Pa the structured emulsion has a G’ of 3022 Pa, which is more than 6x that of mayonnaise (461 Pa). This indicates a material that is stiffer, and more solid-like, which might be unexpected, considering that the Coasun™ product contains an additional 15% water compared to the mayonnaise. The differences in the loss modulus (G’’) is also quite substantial, with the structured emulsion showing a loss modulus over to 7x that of mayonnaise (424 vs 59 Pa).
In 2011, work was completed by Huschka et al. in an attempt to determine how similar this type of structured emulsion would behave to an actual interesterified vegetable shortening (Huschka et al., 2011). The doughs containing structured emulsion showed a lower amount of water absorption compared to all other samples, including the interesterified soy oil, at lipid contents above 6% (Huschka et al., 2011). This suggests the formation of a softer dough which had been ‘shortened’ (Huschka et al., 2011). This prevention of cross-linkages between gluten molecules was especially noticeable in the dough samples using hard wheat flower, which contains a higher protein (gluten) content compared to soft wheat flower (Huschka et al., 2011). Preventing gluten aggregation through the use of shortenings is beneficial for baked products which are not reliant on gluten for structure, such as cakes and tarts (Huschka et al., 2011). Based on these results, it is likely that a structured emulsion (Coasun™) could pose as a viable substitute for highly saturated and trans fatty acid rich shortenings in these types of products. The same ingredients as Coasun™, though not heated and mixed together, were used as a control, and did not demonstrate these same shortening properties, signifying the importance of the specific structure of these emulsions, rather than simply the presence of the ingredients (Huschka et al., 2011).
Other than a low saturated, and 0 trans fat content, additional physiological benefits have been discovered after consuming these multilayer structured emulsions. The unique structure of Coasun™ also has shown the ability to help regulate blood lipid and insulin responses in humans, and lower postprandial triacylglycerol levels (Marangoni et al., 2007; Rush et al., 2009). Once again, these lowering effects were not demonstrated when the raw ingredients alone were consumed, or when the structure was destroyed by cooking (Rush et al., 2008). Furthermore, there is potential for nutraceuticals such as phytosterols, omega-3 fatty acids, fat soluble antioxidants, and other compounds (which will be discussed further later in this chapter) to be incorporated into the water or oil component of these structured emulsions as an added nutritional benefit (Zetzl and Marangoni, 2011).
Due to the increased incorporation level of water, the final product is fairly inexpensive, especially when its multitude of potential health benefits are taken into consideration. Though continued research is required as to how these structured emulsions behave in food systems, they may be one of the best solutions to the trans fat dilemma, especially in the bakery industry where its shortening-like structure would be ideally suited (Lin and Appleby, 2012).
Organogels, also known as oleogels, can be defined as an organic liquid entrapped within a thermo-reversible, three-dimensional gel network (Zetzl and Marangoni, 2011). The process of forming an organogel is called organogelation. Oil-binding molecules were certainly not unheard of in the scientific community and industry prior to the 1990’s; however it was not until the late 1990’s that the potential for oil binding molecules to be used as a vegetable oil structurant and food ingredient began to be realized (Co and Marangoni, 2012). As of 2012, there have been several reviews published regarding the many known organogelators, their properties, advantages, and disadvantages (Pernetti et al., 2007a; Bot et al., 2009; Rogers, 2009; Co and Marangoni, 2012).
The following are general categories of network-forming edible oil structurants that have been identified: Monoacylglycerols (MAGs), fatty acids, fatty alcohols, waxes, wax esters, sorbitan monostearate; as well as the following mixtures: fatty acids and fatty alcohols, lecithin and sorbitan tri-stearate, and phytosterols and oryzanol (Pernetti et al., 2007a). In addition, the following organogelators or mixtures thereof are well known for having an ability to structure edible oils: 12-hydroxystearic acid (Rogers et al., 2007; Terech and Weiss, 1997; Rogers et al., 2008a; Rogers et al., 2008b), ricinelaidic acid (Wright and Marangoni, 2006), candelilla wax (Toro-Vazquez et al., 2007), rice bran wax (Dassanayake et al., 2009), sunflower wax (and others) in soybean oil (Hwang et al., 2012), several waxes in canola oil (Blake and Marangoni, 2013), mixtures of β-sitosterol and γ-oryzanol (Bot and Agterof, 2006), mixtures of stearic acid and stearyl alcohol (Gandolfo et al., 2003), and mixtures of lecithin and sorbitan tri-stearate (Pernetti et al., 2007b), and more recently mixed ceramides and ethylcellulose (Rogers, 2011; Zetzl et al., 2012).
Waxes and Wax Organogels
For decades waxes have played an important part outside of the food industry. A wax can be defined as a fatty substance that contains long hydrocarbon chains with or without a functional group (Dassanayake et al., 2011). It is unknown as to how far back their uses go, however the oil structuring ability and texture they provide to products such as lipstick, lip balms, and lotion bars is a necessity (Toro-Vazquez et al., 2007). Previously, to structure oil effectively, waxes had to be used at levels close to or in excess of 5%, making them impractical for most food uses, as they would impart a waxy mouthfeel. Carnauba wax for example is only able to structure oil at levels in excess of 4% (Dassanayake et al., 2009). More recent studies have shown the superior oil binding ability of certain waxes, which are able to gel oil at levels as low as 1% (Toro-Vazquez et al., 2007; Dassanayake et al., 2011; Toro-Vazquez et al., 2011; Blake and Marangoni, 2013). With wax incorporation levels of only a few percent of the fat phase, this may provide a texture and mouthfeel that is more acceptable to consumers.
Candelilla wax is one such wax that shows great potential as an organogelator. Obtained from the leaves of a small shrub native to the southern United States and northern Mexico, candelilla wax consists of 49-50% n-alkanes with 29 to 33 carbons, and 20-29% esters of acids and alcohols with 28 to 34 carbons (Toro-Vazquez et al., 2007; Toro-Vazquez et al., 2011). Candelilla wax has been shown to structure safflower oil at levels as low as 1%, while actual gelation was not found to occur until concentrations were raised to 2% (Toro-Vazquez et al., 2007; Toro-Vazquez et al., 2011). This wax appears to be limited by the type of crystals it forms, which are usually less than 10 μm in size and spherulitic in shape (Toro-Vazquez et al., 2011). To effectively entrap oil, much longer and thinner crystals, such as those formed when using rice bran wax, are usually needed (Co and Marangoni, 2012). Wax derived from rice (Oryza sativa) bran possesses long needle-like crystals in oil, ranging from 20-50 μm, are very effective in entrapping oil within a crystalline matrix (Dassanayake et al., 2011; Co and Marangoni, 2012). These crystalline strands are so effective in fact that they have been shown to gel oil as low as 1% w/w (Blake and Marangoni, 2013).
With the large production levels of rice in eastern Asia, rice bran wax is very inexpensive, and was traditionally considered a waste product of the rice milling process (Dassanayake et al., 2011). This means that it is largely available, and cost effective, with the possibility to greatly reduce the amount of saturated fatty acids, while eliminating any trans fatty acids. Unfortunately, gels containing only 1% wax are very soft, and oily in appearance. It is probable that much higher levels would have to be used to produce a fat that is similar to lard or shortening in texture. At such a high incorporation level, it is unknown as to how noticeable and ‘waxy’ the mouthfeel of the fat would be, though this would certain have a negative effect in regards to consumer perception.
Wax microstructure provides a possible explanation for the greater gelation power of rice bran wax, sugarcane wax and sunflower wax over other waxes. Carnauba wax, the wax with the highest critical gelator concentration, formed large, open, dendritic clusters or aggregates, which are not very effective in entrapping oil. Though the structure of candelilla wax is better for gelling oil compared to carnauba wax, it is only rice bran wax that forms very long, needle-like crystals, which are very conductive for forming gels (Co and Marangoni, 2012; Blake, Co and Marangoni, 2013).
Sunflower wax, a wax derived from sunflower seeds, has barely been mentioned in literature compared to these three other waxes, yet it may provide oil binding properties that are similar or even superior to rice bran wax (Hwang et al., 2012; Blake, Co and Marangoni, 2013). Sunflower wax forms crystals that are in excess of 100 μm, allowing for more junction zones to be formed along each crystal strand, increasing the strength of the gel network (Hwang et al., 2012; Blake, Co and Marangoni, 2013). Compositional purity has also been shown to have an effect on wax gelation. Minor components in the waxes have the potential to act as impurities, impairing gelation and changing morphology in regards to crystal size and potentially shape (Blake, Co and Marangoni, 2013). While rice bran wax consists of over 90% esters, sunflower wax contains 97-100% esters, and contains the fewest minor components out of the four aforementioned waxes (Blake, Co and Marangoni, 2013). This high level of compositional purity also aids in the understanding as to why rice bran and sunflower wax are such good organogelators in comparison to other waxes. Though low critical gelator concentrations can be achieved when using these two waxes, it seems that their ability to hold the oil in its gel state is fairly low, with % oil loss exceeding 50% when gels were made with 1% wax (w/w). In comparison, candelilla wax showed only a 25.8% oil loss at the 1% (w/w) incorporation level, and only 11.1% oil loss at the 2% (w/w) incorporation level (Blake, Co and Marangoni, 2013). Though oil loss values are dependent on the test conditions, these differences show that there are a variety of factors that should be taken into consideration when choosing a wax for organogelation purposes, not just the critical gelation concentration.
Clearly, there is great potential in the field of waxes to structure oils, though many questions still remain, especially in regards to how these gels will behave in food systems. Though they have the possibility to become a substitute or solution to trans fatty acids in the future, a significant amount of research and development must still take place in this field.
Oleogels made using 12-hydroxystearic acid
Similar to waxes, the low molecular weight organogelator 12-hydroxystearic acid also has the ability to gel vegetable oil at levels below 2% (w/w) (Hughes et al., 2011). This molecule is derived from castor oil, and has been used for decades by industry in the production of lithium grease (Co and Marangoni, 2012). Structurally, 12-hydroxystearic acid (12-HSA) is 18 carbons long and possesses a hydroxyl group at position 12 (Rogers and Marangoni, 2011). Oleogels are formed by heating the 12-HSA-in-oil mixture to above the melting point of the 12-HSA, which occurs at approximately 76oC (Co and Marangoni, 2012). Upon cooling, 12-HSA fibers form throughout the oil, growing one-dimensionally to hundreds of micrometers in length. A bright-dark striation pattern can be seen on each of these fibrillar crystals. This is caused by a helical twist of the 12-HSA fibers, causing them to pass in and out of birefringence under polarized light (Rogers and Marangoni, 2011; Co and Marangoni, 2012). An extensive characterization of these oleogels has been previously described by Rogers and Marangoni in 2011, and Co and Marangoni in 2012, though it is perhaps the health implications of consuming such an oleogel that are of greatest interest to the food industry (Rogers and Marangoni, 2011; Co and Marangoni, 2012).
In a review chapter by Hughes et al. in 2011, the results of a clinical trial were reported where subjects were fed standardized test meals which differed only by the fat source they contained, which were butter, margarine, canola oil, or gelled canola oil (using 12-HSA) (Hughes et al., 2011). After consumption of the test meals, blood samples were taken every hour for six hours and were analyzed for triacylglycerols, free fatty acids, glucose, and insulin levels. No significant differences were found between the treatments in regards to glucose or insulin levels; however the oleogel and canola oil meals significantly reduced the serum triacylglycerol response curves compared to those from the margarine and butter meals, for the majority of the measurements (Hughes et al., 2011). The oil gelled with 2% w/w 12-HSA also showed the lowest maximum serum free fatty acid levels compared to all other meals (though it was not significantly less than the meal containing canola oil) (Hughes et al., 2011). These effects are added benefits that go beyond the fatty acid compositional benefits provided by all oleogels made with a high percentage of vegetable oil. Though this study utilized 12-hydroxystearic acid, it is possible that, if consumed in a similar manner, oleogels made using other oraganogelators could show similar beneficial physiological effects.
While 12-HSA is an exceptional organogelator, it unfortunately does not currently have full food grade status (Co and Marangoni, 2012). Additionally, for any food systems where the shearing or mixing of these oleogels would be required, the use of 12-HSA as the organogelator would not be possible, as the long fibrillar crystals are very delicate and essentially shatter under these conditions. This damage to the fibrillar network is non-recoverable, and results in a high percentage of oil loss. It is therefore likely that while oleogels show a great deal of potential in food systems, it is probable that other organogelators, such as polymers, will be used in place of the fibrillar network forming 12-HSA.
Ethylcellulose (Polymer) Oleogels
For the purposes of creating a food grade oleogel, the use of a polymer such as ethylcellulose (EC) is highly novel, though this is rather surprising considering that its solubility properties were reported as early as 1937, over 75 years ago. The work of W. Koch stated that “solubility in both polar and nonpolar organic solvents is best with ethylcellulose of substitutions between 2.4 and 2.5 ethoxy groups” (Koch, 1937). At the time, this must have seemed like a trivial detail, however, this means that EC can be used as an organogelator of food grade oils, as a common vegetable oil would classify as a nonpolar solvent. It is likely that this detail was originally simply overlooked, as there was no need to create a substitute for trans, or saturated fats. Not until the past decade has the potential of oleogels, and in particular polymer oleogels, become fully realized.
Ethylcellulose is a chemically modified version of the plant cell wall based polymer, cellulose. Ethylcellulose differs from cellulose only by the substitution of hydroxyl groups for ethoxyl groups, with a maximum of three substitutions possible. Solubility in water is achieved when the average substitution is between 1 and 1.5, while only in the narrow range of 2.4 - 2.5 substitutions, 47 – 48% ethoxy content, is solubility in oil possible (Zetzl and Marangoni, 2011; Zetzl et al., 2012). Though solubility in oil was not a requirement of the commercial product, the 2.4 – 2.5 substitution level has been the standard substitution level used by industry since the 1930’s. Compared to organogelators used in the past, ethylcellulose is rather inexpensive and can be produced (and purchased) in large volumes. This makes the large scale use of EC for organogelation both possible and feasible.
For solubility in oil to occur, the ethylcellulose must be heated above the glass transition temperature (Tg) which occurs at approximately 130oC. A variety of molecular weights are available, expressed as a cP value, with 10 – 100 cP being the range that is most practical for organogelation purposes. Molecular weights can be calculated, but they are not provided by ethylcellulose suppliers (Zetzl et al., 2012). Table 2 shows the melting point, as well as the onset, mid-point, and final temperature for the glass transition of three varieties of ethylcellulose, in addition to the matching cP values and calculated molecular weights. Though it is only the Tg that is needed to create a gel, the melting point for these varieties is useful information, because at temperatures above this point, it is highly likely that the polymer will begin to break down/degrade. By remaining within the functional range between the Tg and the melting temperature, the quality of the EC can be preserved while retaining its ability to make oleogels.
A great deal is already known about the mechanical properties of EC oleogels. Recent studies have shown that the mechanical strength of these gels is highly dependant on the fatty acid composition of the vegetable oils used in making the gels (Zetzl et al., 2012; Laredo et al., 2011). Oils such as canola, which contain a fairly low comparative degree of unsaturation (approximately 60 % oleic acid, 18:1), produce fairly soft gels (Zetzl et al., 2012; Laredo et al., 2011). Flaxseed oil, which contains close to 60 % linolenic acid (18:3), produces substantially harder gels (Zetzl et al., 2012; Laredo et al., 2011). This increase in gel hardness corresponds to a statistically similar change in the elastic modulus of gel samples made with different vegetable oils. It is believed that these differences are caused by a change in the molar density of the oils within the gels (Zetzl et al., 2012; Laredo et al., 2011). Essentially, oils with a higher degree of unsaturation are able to pack more tightly within the gel network, causing a firmer gel (Zetzl et al., 2012; Laredo et al., 2011). Even prior to gelation, a relationship can be seen regarding level of unsaturation and molar density. At 25oC, canola oil has a density of 0.9134
g/cm-3, soybean oil 0.9167 g/cm-3, and flaxseed oil 0.9250 g/cm-3 (Laredo et al., 2011). Attenuated total internal reflection infrared spectroscopy has been utilized to look at the differences between these oils in their gelled state. As the level of unsaturation increased, so did the intensity ratio between the band at 3007 cm-1 (=C-H stretching) and 2870 cm-1 (CH3 symmetric stretching). This signifies an increasing difference in the level of =C-H stretching between the gels and the pure oils as unsaturation increases (Laredo et al., 2011). In addition, Raman spectroscopy revealed a higher number of gauche conformers in the gels compared to the pure oils, with the fatty acid chains becoming more melted or bent when they were in their gelled state (Laredo et al., 2011). This supports the hypothesis that the linolenic acid molecules in flaxseed oil are more tightly packed within the gel network compared to the oleic acid molecules in canola oil. It is possible that analysis of scanning electron and atomic force micrographs could provide additional evidence regarding the density of the gel network when using vegetables of different unsaturation levels.
The effect of polymer molecular weight has also been shown to have a significant impact on the mechanical properties of these polymer oleogels. As previously mentioned, molecular weight is expressed as a cP value, with ethylcellulose of 10 cP possessing a lower molecular weight on average than 20, 45, or 100 cP. Increases in molecular weight have been shown to produce gels that were significantly harder than low molecular weight varieties. Compared to 10 cP, oleogels made with 45 cP are nearly 10 x harder, while gels made using 100 cP ethylcellulose are more than 20x harder when using soybean oil (Zetzl et al., 2012). As higher molecular weight varieties of ethylcellulose would contain longer polymer chains, it is hypothesized that these longer chains would be able to form a higher number of junction zones, improving network strength.
Polymer concentration is one additional factor that has a very significant effect on gel strength. When using 45 cP ethylcellulose, critical gelator concentrations of 4% and 6% were determined when using soybean and canola oil respectively (Zetzl et al., 2012). In addition, when the hardness values at different polymer concentrations were plotted, both canola oil and soybean oil followed a power law function with a scaling factor of approximately 6, with an r2 value of 0.99 (Zetzl et al., 2012). Using this data, it might be possible to predict the approximate hardness of gels made with a certain polymer concentration.
Production considerations and food applications of ethylcellulose oleogels
On a slightly negative note, it appears that the preparation method used to produce ethylcellulose oleogels has a significant effect on gel properties, in particular, the number of oxidation products found in the sample (Gravelle et al., 2012). An increase in the thiobarbituric acid (TBA) value can be seen with extended holding time above the glass transition temperature (Gravelle et al., 2012). This value, along with the peroxide value, can give a good indication as to the level of oxidation in a vegetable oil. For canola oil oleogels, the TBA value increased from just over 0.08 to close to 0.13 after 90 minutes holding time above the Tg (Gravelle et al., 2012). The peroxide value of these gels also increased from approximately 2.5 meq/kg to approximately 14 meq/kg after 60 minutes (Gravelle et al., 2012). It was suggested that a holding time of 20 minutes should be used, as any longer and the oil quality would no longer be acceptable based on the peroxide values (Gravelle et al., 2012). In addition, an increase in the % total polar components was also noted as a function of holding time, increasing from 2.5% at 0 minutes to 4.0% and 6.5% after 60 and 120 minutes respectively (Gravelle et al., 2012). The higher prevalence of these oxidation components caused a significant increase in the mechanical strength of the oleogels. It is believed that as the polarity of the oil increases, it is able to form hydrogen bonds to the ethylcellulose, helping to increase the strength of the gel network (Gravelle et al., 2012).
When heating a vegetable oil to temperatures in excess of 100oC, oxidation will always be a factor. As previously mentioned, to produce these gels, a temperature in excess of 130oC is required, above the glass transition temperature of the ethylcellulose powder. This causes not only oxidation of the oil, but also has the potential to degrade any surfactants used, in addition to degradation of the polymer itself. It was therefore necessary to develop a standard procedure for the production of these gels, as described by Gravelle et al. in 2012, to improve reproducibility and reduce oxidation (Gravelle et al., 2012). By combining this improved production method with an antioxidant such as butylated hydroxytoluene (BHT), it is likely that the overall acceptance of the produced oleogels in regards to palatability would be greatly improved.
Something unique about ethylcellulose oleogels compared to most other oleogels, is that they have actually been used in real food systems as a replacement for more highly saturated animal fats. A series of recent studies have discussed potential applications of these gels, including their use in cookies, comminuted meat products, creams for various fillings (predominately baked goods), and chocolate (Zetzl et al., 2012; Stortz et al., 2012; Stortz and Marangoni, 2011). Ground and comminuted meat products have been successfully made using 100% replacement of added animal fat with ethylcellulose oleogels. This replacement significantly reduced the amount of saturated fat in these products. While non-gelled oil tends to leak out of the ground products, or make comminuted meat products significantly harder and chewier, gelling the oil prevents both of these problems. Oil is immobilized, and is not lost from breakfast sausages upon cutting, while cooked comminuted meat products made with gelled canola oil showed no significant differences in regards to chewiness and hardness, when compared to a beef fat control product (Zetzl et al., 2012). This textural improvement compared to products made with un-gelled oil appears to be caused by an increase in the size of the fat/oil globules in the cooked meat batter. The average fat globule size is greatly increased once the oil is in its gel form. Though these globules are still smaller than those found in the beef fat products, this increase in size still has a great impact on product texture. It is believed that the smaller globules in the canola oil product allow for a larger surface area to be coated by proteins, increasing the strength of the protein network (Zetzl et al., 2012).
Outside of meat systems, ethylcellulose oleogels have also very recently been used in the production of pastries, in particular, laminate type products, which are notorious for being difficult to produce with any fat other than butter. Pastries containing 50% replacement of butter with an ethylcellulose oleogel have been successfully prepared, significantly reducing the amount of saturated fat, while still allowing the formation of lamination layers. Creams for the purpose of fillings in the baking industry can also be made using ethylcellulose oleogels, reducing oil migration from the filling into the surrounding product and also improve the fatty acid profile of the cream. Creams consisting of 60% gelled vegetable oil and 40% interesterified palm oil showed almost 0% oil leakage after 12 days while creams made with ungelled oil showed close to 25% oil leakage (wt%/g sample) after 12 days (Stortz et al., 2012).
Though the primary focus of these replacement experiments was to reduce the amount of saturated fat while retaining functionality, it may be very possible to use ethylcellulose oleogels as a method to reduce trans fat in similar products. The baking industry in particular still has many items, including donuts, muffins, and cookies, which are high in saturated fat, and still contain trans fat. If these gels are able to replace saturated fat in such a wide variety of products, while at the same time retaining product texture and palatability, it is possible they can be used in similar products to finally eliminate any trans fat which they still contain.
In North America ethylcellulose has now GRAS status and is approved for direct and indirect food uses, such as use in inks to mark fruits and vegetables, and as a component of paper and paperboard that is in contact with fatty or water-based foods (Zetzl and Marangoni, 2011). In Europe, ethylcellulose has already been approved for food uses since late 2006 (Zetzl and Marangoni, 2011). Internationally, the Food and Agriculture Organization of the United Nations in collaboration with the World Health Organization has listed ethylcellulose as a food additive that may be used in a variety of foods under the conditions of good manufacturing practices as outlined in the Preamble of the Codex GSFA (FAO and WHO, 2012). Just some of the foods listed include processed comminuted meat, poultry and game products, fat spreads, fat emulsions, cheeses, bakery wares, and confectionery products (FAO and WHO, 2012). Though EC may not yet have full food grade status worldwide, it is highly likely that such a development will occur in the near future.
Using oleogels for nutraceutical delivery or encapsulation
There have been recent discussions into how to make an oleogel, usually consisting of at least 90% vegetable oil, even healthier. One of the easiest ways to do so would be to use the oleogel to encapsulate or deliver nutraceuticals. Nutraceuticals, can be defined as “a food (or part of a food) that provides medical or health benefits, including the prevention and/or treatment of a disease” (Brower, 1998). This could include something as common as fruits and vegetables, or an isolated compound such as lycopene, which has been shown to improve human health in some way. For incorporation into an oleogel, it would be most advantageous to use a fairly purified compound, as it would not be hindered or restricted by the food matrix where it was originally contained. Compounds such as the omega-3 fatty acids, the carotenoids β-carotene and lycopene, phytosterols, coenzyme Q, and vitamin E have all been identified as potential compounds of interest for incorporation into oleogel systems (Zetzl and Marangoni, In press). These compounds are discussed in detail elsewhere; however, some of their benefits include decreased platelet aggregation, blood viscosity, andfibrinogen, antioxidant properties, as well as lower incidences of chronic disease, including cardiovascular disease and certain cancers, in particular, prostate, breast, and lung cancer (Zetzl and Marangoni, In press). Clearly, the addition of any one of these compounds to an oleogel would have a significant impact on its healthiness. The availability / presence of dietary fat also has a significant impact on the absorption of most of the aforementioned molecules, as they are all at least partly fat soluble.
The difficulty in incorporating any one of these nutraceutical compounds lies in trying to minimize their degradation. Many of these compounds contain a large number of unsaturations, and would degrade very quickly if exposed to the high heat required to create an ethylcellulose oleogel for example. By adding these compounds during the cooling process, just before gelation occurs, this could maximize the quality and effectiveness of any added nutraceuticals.
Phytosterol-oryzanol mixtures for oraganogelation purposes
Phytosterols are compounds of particular interest, as they not only possess cholesterol-reducing properties, but also certain varieties can be used as organogelators (Bot and Flöter, 2011). Mixtures of β-sitosterol and γ-oryzanol in vegetable oil can be used to form optically transparent (when a 1:1 molar ratio of structurant is utilized) or hazy/semi-opaque gels at incorporation levels as low as 2-4% total sterols at 5oC (Bot et al., 2009; Bot and Flöter, 2011). It is proposed that these components are able to structure the vegetable oil by forming tubules, with a diameter of approximately 7.2 nm and a wall thickness of 0.8 nm (Bot and Flöter, 2011). These tubules are able to aggregate and interact, effectively forming a network and entraping the liquid oil (Co and Marangoni, 2012). The small size of these tubules, smaller than the wavelength of visible light, gives an explanation as to why they are able to form optically transparent gels (Bot and Flöter, 2011). Though these phytosterol-oryzanol mixtures are very effective at gelling oil when used together, this gelation does not take place when one of the components is excluded. Instead, sterol or sterol ester crystals are formed, and simply sediment to the bottom of the container without gelling or structuring the liquid oil (Co and Marangoni, 2012).
The β-sitosterol and γ-oryzanol mixture in vegetable oil is one of the first oleogel systems which consists entirely of food grade or near-food grade materials (Bot and Flöter, 2011). This is a major step forward in the field of organogelation, as most organogelators to date have not been even given GRAS (generally recognized as safe) status or letters of no objection from governing bodies (Co and Marangoni, 2012). An extensive summary of the β-sitosterol and γ-oryzanol system was completed by Bot and Flöter in 2011, providing a concise review of the work completed on these components as organogelators thus far (Bot and Flöter, 2011).
Though the prospect of phytosterol based oleogels appears very promising, they unfortunately suffer from one significant limitation in regards to food applications. When in the presence of water, the organogelation components face a significantly reduced ability to structure oil (Bot and Flöter, 2011). In a system such as a baked good or meat emulsion, compatibility with water is a critical property. As the gelling capabilities of β-sitosterol and γ-oryzanol are so greatly affected by water, is has been suggested that they will most likely only be effective gelators in more pure systems, rather than in complex food systems (Bot and Flöter, 2011). In addition, the high cost of sterols and sterolesters further renders these organogelators applicable for only more specific applications, where a greater cost can be justified. Therefore, even with the promising health benefits of such a nutraceutical organogelator, it is unlikely that we will be seeing a phytosterol-based oleogel on supermarket shelves in the near future.
Even though clearly many technical challenges still exist, there have been great advancement in recent replacements for trans fatty acids, in particular, the development of structured emulsions using monoglycerides and edible oleogels. The promise of incorporating additional nutraceuticals into these substitutes further increases their value, as they would become essentially free of unhealthy fatty acids, and would contain highly beneficial nutraceuticals. Due to these factors, both structured emulsions and certain edible oleogels could be considered ‘solutions’ to the trans fat problem.
The edible oil industry, along with researchers in government, academia, and the agribusiness sector have made much progress in removing trans and saturated fats from the food supply. New technologies, along with modification of older ones, have provided the consumer with healthy dietary alternatives needed for improved health and nutrition. Plant breeding and biotechnology will continue to be fruitful areas for research on not only foods and feeds but fuels as well. The oleogel/structured emulsion field offers much promise in food applications. The progress made in eliminating unhealthy oils has been both time consuming and expensive. Only time will tell whether the means justifies the end. The removal of trans fats took on a new dimension when the FDA recently announced a removal of trans fats from GRAS status. If enacted, partial hydrogenation may be removed from the food manufacturers’ tool bag.
|Table 1. Fatty acid composition (wt%) of common fats and oils from vegetable sources
(Gunstone and Harwook, 2007)
|Table 2. Fatty acid composition of total Arabidopsis leaf lipids and major lipid fractions of spinach chloroplasts
|MGD = monogalactosyldiacylglycerol; DGD = digalactosyldiacylglycerol; SQD = sulfoquinovosyldiacylglycerol; PG = phosphatidylglycerol|
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- Erickson, M. (2007) Deep frying. AOCS press 2nd Ed, Champaign, IL
- Gupta, M., P.J. White, K.A. Warner (2004) Frying Technology and Practices. AOCS Press, Campaign, IL.
- Warner, K.A. and W. Fehr (2008) Mid oleic low linolenic acid soybean oil: A healthful, new alternative to hydrogenated oil. J.Am.Oil Chem.Soc. (85) pp 45-951.
General Fats and oils/food uses (Books)
- Akoh, C. and D. Min, (2002) Food lipids 2nd Ed., Marcel Dekker, New York.
- Bailey’s Industrial oil and fat products (2005), (Ed.) F. Shahidi, 6th revision, (6 volumes).
- Dijkstra, A.J. (2013) Edible oil processing from a patent perspective. Springer Publishing, New York.
- Hamm, W., R.J. Hamilton and G. Calliauw (2013) Edible Oil Processing, 2nd Ed. Wiley Blackwell.
- Gunstone, F.G. (1997) Lipid Technologies and Applications. Marcel Dekker, New York.
- Gunstone, F.G. (2006) Modifying fats for food use. Food. Woodhead Publishing, Cambridge, UK.
- Gunstone, F.D. (2011) Vegetable Oils in Food Technology. Blackwell Wiley, Oxford, UK.
- Hamm, W., R.J. Hamilton and G. Calliauw (2013) Edible Oil Processing, 2nd Ed. Wiley Blackwell.
- Moran, D.P.J. and K.K. Rajah (1994) Fats in Food Products. Blackie-Chapman Hall, Glasgow, UK.
- O’Brien, R. (2009) Fats and oils, Formulating and processing for application. CRC Press 3rd Ed.
- Weiss, T.J. (1983) Food oils and their uses. AVI Publishing Co, Westport CT.
Palm oil and palm kernel/ fractions in food applications, spreads, shortenings (Patents and open literature)
- Aini Idris, N. and S. Samsuddin (1992) Developments In food uses of palm oil: A brief Review. Palm Oil Developments, PORIM (16).
- Andersen, A.J.C. and P.N. Williams (1965) Margarine. Pergamon press 2nd Ed. UK.
- Anon. (1974) Shortenings, margarines and food oils. Noyes Data Corporation, Park Ridge, NJ, USA (Excellent review of Patent Literature from 1960-1974).
- Babayan, V. (1966) Margarine oil and margarine made from. US Patent 3,268,340.
- Basiron, Y. (2005) Palm Oil in Bailey’s Industrial Oil and fat products. (Ed.) F. Shahidi, John Wiley and Sons, New York, Volume (2) pp 333-429.
- Berger, K. (2001) Palm Oil in Structured and Modified lipids. (Ed) Frank Gunstone. Marcel Dekker, New York pp 119 -153.
- Berger, K. (1986) Palm oil products. Why and how to use them. Fette.Seifen Anstrich pp 250-258. (Good reference with fatty acid composition and blends for margarines) (Also Food technology, Sept 1986 pp 72-79. Berger K, (2010).
- Berger, K. W., L. Siew, and F. Oh (1982) Factors affecting slip melting points of palm oil products. J.Am. Oil Soc. (59) pp 244-249.
- Berger, K. and Y.K. Teah (1988) Palm oil: The Margarine Potential. Food Manufacture International (20-22) (Nov/Dec).
- Berger, K. (1993) Food product formulation to minimize the content of hydrogenated fats. Lipid Tech. (4) pp 37-40.
- Beveridge, J.M., W.F. Cornell and G. Mayer. Circulation (12) pp 499 1955.
- Block, J.M., et al., Blending process optimization into special fat formulations by neural networks. J.Am.Oil Chem.Soc (74) pp 1537-1541. (Also J.Am. Oil Soc. (76) pp 1357-1361) (Statistical approach to neural networks).
- Defense, E. (1985) Fractionation of palm oil. J.Am. Oil Soc. (62) pp 376-385.
- DeMan, l., C.F. Cher and J. M. DeMan (1991) Composition physical and textural characteristics of soft (tub) margarines. J. Am. Oil Chem. Soc. (68) pp70-73.
- Frommhold, K. (1974) Margarine fat containing interesterified constituents. US Patent 3,796,581.
- Galenkamp, H. (1965) Process of preparing a fat product which after plasticizing can be used as a spreading, baking and frying fat and a process of preparing a margarine using this fat product. US Patent 3,210,197.
- Gercama, A. and R. Schijf (1985) Margarine fat blend with a reduced tendency to sandiness. US Patent 4,501,764.
- Gooding, C.M. (1963) Highly nutritious fat composition. US Patent 3,099,564.
- Graffelman, H. (1966) Margarine fat and process for preparing a spread. US Patent 3,617,308 (Original BECEL patent).
- Heider, H. and T. Wieske (1980) Margarine Fat. US Patent 4,230,737.
- Holemanns, P., R. Schijf and K. van Putte (1988) Fat and edible emulsions with a high content of cis polyunsaturates. US Patent 4,791,000.
- Kinsell, L.W., G.D. Michaels, G.C. Cochrane, G. Partridge, J.P. Jahn and H.E. Balch (1954) Diabetics (3) pp 113-119.
- Kirkeby, P.G. (2008) Food products without trans fatty acids, in Trans Fatty acids. (Eds.) A.J. Dijkstra, R.J. Hamilton and W. Hamm. Blackwell Publishing, UK pp 219-234 (Also same book pp 181-202, DeGrey and Dijkstra, Fractionation and interesterification; Podmore, Food applications of trans fatty acids pp 203-218; A.J. Dijkstra, Controlling physical and chemical properties of fat blends pp 132-146).
- Kun,T.Y., N. Sudin and H. Kifli (1992) Interesterification- A useful means of processing palm oil products for use in table margarine. Palm Oil Developments, PORIM (16) pp 6-10.
- Kun, T.Y., and A. Ibraham (1991) Hydrogenation is often unnecessary with palm oil. Palm Oil Developments, PORIM (15).
- Landmann, W. and R.O. Feuge (1954) Consistency of mixtures of cottonseed and Paraguayan palm kernel oil. J. Am. Oil Chem. Soc. (33) pp 308-311.
- Laning, S. (1985) Chemical interesterification of Palm, palm kernel and coconut oils. J. Am. Oil Chem. Soc. (62) pp 400-407.
- Lefebvre, J. (1983) Finished product formulation. J. Am.Oil Chem. (60) pp 295-300.
- Lin, S.W. (2002) Palm oil in Vegetable oils, Food Technology: Composition, properties and uses. (Ed.) F.D. Gunstone. Blackwell CRC Press, Oxford, UK pp 59-127.
- List, G.R. and T. Pelloso (2007) Zero/low trans margarines, spreads and shortenings, in Trans fats in Foods, (Ed.) G.R. List, D. Kritchevsky, N. Ratnayake. AOCS Press, Champaign, IL pp 155-175 (data on composition cholesterol lowering spreads, including smart balance).
- Maclellan, M. M., (1983) Palm oil. J.Am. Oil Soc. (60) pp 368-373.
- Mainal, J. (2003) Applications of palm based interesterified fats. Palm Oil Developments, PORIM (39) pp 11-21.
- Majumdar, S. and D.K. Bhattacharyya (1986) Trans free vanispati from palmsterain and vegetable oils by interesterification process. Oleagineux (41) pp 236-238.
- Mat Dian, N., N. Ibrahim and N. Aini Idris (2006) Interesterified palm products for solid fat applications. Palm Oil Developments (46) pp 12-16.
- Minail, J. (2003) An introduction to random interesterification of palm oil. Palm Oil Developments, PORIM (39) pp 1-6.
- Niordin, A., M. Simeh, M. Mahidin and F. Sheriff (2010) Impact of labeling on palm oil in the US market. Palm Oil Developments (56) pp 5-9.
- Norani, L., M.S. Embong, A. Abdullah and C.H. Oh (1992) Characteristics and performance of some commercial shortenings. J. Am. Oil Chem. Soc. (69) pp 912-916.
- O’Brien, R.D. (1988) Fats and oils: Formulating and Processing for applications. Technomic Publishing, Lancaster, PA, 1st Ed. p 133.
- Okamoto, T., T. Ushikusa, T. Maruyama, H. Kanematsu and M. Shimura (1988) General properties of Commercial margarines in Malaysia, Singapore and Thailand. Yukagaku (37) pp 586-588.
- Ong, A.S.H. (1984) Highlights of research on food uses of palm oil. Palm Oil Developments, PORIM (1) pp 4-6.
- Ong, A.S.H, Y.M. Choo and C.K. Oii (1995) Developments in Palm Oil, Developments in Fats and Oils. (Ed.) R.J. Hamilton. Blackie Academic, New York pp 153-191.
- Osman, A. and N. Aini Idris (1999) Physical and chemical properties of shortenings from palm oil/tallow blends with and without interesterification. J. Palm Oil Res. (11) pp 1-10.
- Pande, G., C. Akoh and O.M. Lai (2012) Food uses of Palm oil. Palm oil: Production, processing, characterization and Uses, (Eds.) O.M. Iai, C.P. Tan and C. Akoh. J.Am.Oil Soc. Press, Champaign IL, pp 561-586.
- Parodi, P.W. (1976) Composition and Structure of some consumer available edible fats. J. Am. Oil Chem Soc (53) pp 530-534.
- Phillips, R. (1959) Emulsified oleaginous spread containing essential fatty acids and process for making same. US Patent 2,890,959.
- Podmore, J. (2001) Spreads In Structured and Modified Lipids. (Ed.) Frank Gunstone. Marcel Dekker, New York pp 423-453.
- Portman, O.W., J. Hegsted, M. Stare, F.J. Bruno, D. Murphy and R. Sinsteria (1956). Journal Exp. Med. (104) pp 817-828.
- Quality and functions of palm oil in food applications: A Layman’s Guide. Malaysian Palm Oil Council, Malaysia pp 1-116.
- Razali, I., A. Haizam and M. Johari (2005) Palm Oil – The healthier choice for fast food industries. Palm Oil Developments (45) pp 16-29.
- Sahri, M. and N. Aini Idris (2006) Properties of palm oil margarine during storage: Effects of Processing conditions. Palm Oil Developments (45) pp 20-26.
- Schmidt, W. (1986) Low trans fats and oil and water emulsion spreads containing such fats. US Patent 4,610,889.
- Schmidt, W. (1986) Edible fat and a process for producing such fat. US Patent 4,567, 056.
- Snodgrass, K. (1930) Margarine as a butter substitute, Fats and Oils Studies (4). Food research institute. Stanford University, USA.
- Stewart, B., B.B. Eales, A. Antonia and J.F. Brock (1956) Lancet (281) pp 521 -526.
- Talbot, G. (2006) Solvent fractionation of palm oil. INFORM (17) pp 324-326.
- Van Niekerk, P.J. and A. Burger (1985) The estimation of the composition of edible oil mixtures. J. Am. Oil Chem Soc. (62) pp 531-538.
- Van Stuyvenberg, J.H. (1969) Margarine: An economic, social and scientific history 1869-1969. Liverpool University Press (Chapter 3 technology and production, R. Feron pp 83-118; Nutritional and dietetic aspects, A. Frazer pp 123- 162).
- Wassel, P., (2006) Investigation into the performance of emulsified liquid shortenings containing palm based hard stocks. Palm Oil Developments (45) pp 1-9.
- Young, F.P. (1983) Palm kernel and coconut oils: analytical characteristics, process technology and uses. J. Am. Oil Chem Soc. (60) pp 374-379.
- Zakariah, Z, N. Rami and N. Aini Idris (2012) Enzymatic synthesis of Structured lipids through interesterification of palm stearin, Cottonseed oil and palm olein. J. Agrobiotech (3) pp 1-28.
Trans Fats (Books)
- Dijkstra A.J., R.J. Hamilton and W. Hamm (2008) Trans fatty acids. Blackwell.
- Kodali, D. and G.R. List (2005) Trans Fat Alternatives. AOCS Press, Champaign, IL.
- List, G.R., D. Kritchevsky and N. Ratnayake (2007) Trans fats. Foods. AOCS Press.
- Sebedio, J.L. and W.W. (1998) Christie Trans fats, Human nutrition. Oil Press, Dundee.