- 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
- References Cited
On July 11, 2003, trans fat labeling became law with a major key provision stipulating that trans fat was to be listed as a separate line on nutrition labels, but foods containing less than 0.5 grams trans fat per serving (serving size 12-14 grams fats and oils) could be declared zero (Anon., 2003). On January 1, 2006 the new law stipulated that saturated and trans fats were to be included as one line on nutrition labels.
In 1999 the number of zero trans foods was essentially non-existent. The period 2003-2007 saw the number of zero/low trans fat foods increase from approximately 200 to over 1900. A recent report indicates that over the period 2005-2010 the trans fat content of baked goods had decreased from 0.49% to less than 0.2% (Rahovsky et al., 2012). Prior to labeling, baked goods were a major source of trans fats in the diet (Satchithanandam et al., 2004). Government dietary guidelines published in 1980 to 1985 recommended that consumption of saturated acids be avoided. Thus the food industry sought replacements for coconut oil, palm oil, and animal fats in vegetable/dairy, confections, baked goods, margarine, snacks, and cereals. Partially hydrogenated oils (soy, cottonseed, canola), liquid oils, and high stability oils served in many food applications, but saturates were replaced with trans fats (Norris and Gingras, 1990).
A review of new and existing fats and oils used in reduced trans food applications was published in the Journal of the American Dietetic Association (Tarrago-Trani et al., 2006).
Snack food manufacturers took the lead in reformulation by switching from heavily hydrogenated frying shortenings to naturally stable liquid vegetable oils which included corn, cottonseed and sunflower oils. Since these oils are free of linolenic acid and very low in trans fats they proved to be satisfactory alternatives to conventional cube or fluid products. Reformulation in some cases proved to be both expensive and time-consuming. For example, the reformulation (requiring 7200 man hours) of 187 products produced in 46 plants required over 240 analytical tests and 24 consumer studies at a cost of 25million dollars (Eckel et al., 2007). At the time only three oil suppliers were used, plus supply issues had to be overcome. Eventually, a blend of naturally stable oils was chosen as the trans fat replacement.
Soft margarines and spreads proved to be relatively easy to reformulate to zero trans by using both hydrogenated and liquid oil components. However, stick products have proven more difficult to reformulate as more solid fat is required for functionality in baking applications and storage considerations at ambient temperatures. Without question, the most difficult applications for trans fat replacements are baking shortenings. For many years baking shortenings have been formulated from hydrogenated stocks high in trans fats, or to a lesser extent, from animal fat based components. Hydrogenated oils are popular for food formulation (Podmore, 2008) because they are versatile, oxidatively stable, and crystallize well in the desired beta-prime form (Floeter and Duijin, 2006). Animal fats, while essentially trans free, are higher in saturated acids and contain cholesterol which detracts from a health/nutrition perspective. However, from a functional point of view hydrogenated vegetable and meat based shortenings are equivalent with regard to aeration/creaming and icing volume in all-purpose baking applications (Woerfel, 1960). Zero trans baking shortenings formulated from beef tallow and liquid cottonseed oil were introduced in the mid-1890’s and were popular retail/baking products well into the 1930’s. In 1893, Cottolene was marketed by NK Fairbank and Co. and shortly thereafter, Cottosuet was marketed by Swift and Co. Both were very popular among bakers since they performed well in both cake and pie applications.
Processing Methods to Reduce Trans Fats
A review of oil processing methods to reduce trans fats is beyond the scope of this chapter. The reader is referred to a number of excellent reviews on chemical/enzymatic interesterification (Holman and Going, 1959; Screenivasan, 1978; Going, 1967; Rozendaal and Macrae, 1997; Binder et al., 2006). The fractionation of tropical oils has been reviewed by Timms (1997). The patent literature on fractionation has been covered by Dijkstra (2012). Gibon (2006) has reviewed food uses of fractionation products. Technologies to control the physical properties of blended fats by triglyceride compositions have been reviewed by Dijkstra (2008).
Interesterification is an old processing tool dating back to the 1920’s. The process does not change the fatty acid composition or the degree of unsaturation but does alter the triacylglycerol composition, thus affecting the melting profile and crystal habit of a fat. In the 1950’s, interesterified lard was produced by a number of companies (Mattil and Norris, 1953; Hawley and Holman, 1956; Vander Wal and Van Akkeren, 1951) in order to overcome the poor performance of natural lard in cake baking applications (Slater, 1953). While highly prized for pie crusts, natural lard gave poor results in cakes. The glyceride structure of natural lard contains palmitic acid at the two position, whereas after randomization the fat is changed from a beta to a beta-prime crystal. The former allows better incorporation of air into cake batters yielding increased cake volume. In addition, beta prime fats crystallize in finer crystal structures, and upon passage through scraped surface heat exchangers, the fat has a white creamy smooth texture.
Historically, both random (Van Loon, 1927) and directed interesterification (Eckey, 1948) have been used as fat modification tools. In random methods, the reaction is usually carried out with a chemical catalyst (sodium methoxide) at relatively high temperatures (70-100oC), while conducting the reaction at lower temperatures allows the higher melting triglycerides to crystallize out of the reaction medium (Hawley and Holman, 1956; Holman and Going, 1959). More recently the use of enzymes for the modification of food oils has attracted the attention of researchers. An excellent review is presented by Xu et al. (2006).
Fractionation of Tropical Oils
Palm oil has been used in food products for 5000 years. However, the majority of the existing technologies for incorporation into frying fats, baking shortenings and spreads have been developed over the past 30 years or so. Unmodified palm oil performs well in most bakery products. It is rated from suitable to highly suitable for shortenings, margarines, frying fats, cookies, crackers, cake mixes, icings, and biscuits. Palm oil is unsuitable as a coating fat. Fractionation of palm oil yields palm olein, soft stearines and hard stearines. Palm olein is highly suitable in shortenings, margarines, and frying fats. The soft stearines are suitable in most applications, with the exception of icings. Hard stearines find use in shortenings. Hydrogenation of palm oil is useful in shortenings, margarines, frying fats, biscuits, and cookies. Double fractionated palm oil is highly suitable in frying applications. Palm mid fractions are suitable in icings. Palm kernel oil is highly suitable in margarines, coating fats, crackers and biscuits (Ranhotra, 1993). A detailed description of the chemical and physical properties of palm oil and its fractions is given by Kheiri (1987). A number of excellent reviews on the food uses of palm oil have appeared recently (Berger, 2010, 2007; Berger and Aini Idris, 2005) and summarize many of the formulations used for low/zero trans frying, baking shortenings and spreads.
The highly saturated fatty acid composition of palm oil/palm kernel combined with fractionation, hydrogenation, interesterification and blending provide a number of options for trans fat-free foods. The patent literature contains a wealth of information on formulations employing these processing techniques (Gillies, 1974; List and Pelloso, 2007; Dijkstra, 2012; Huizinga et al., 1999; Poot et al., 1978; Dijkshoorn et al.,1982; Schmidt, 1986a,b; Fondu and Willems, 1972; Mat Sahri and Mat Dian, 2011; Van Heteren et al., 1983; Sassen and Westdorp, 2001; Delfosse,1971; Read, 1975; Weiske, 1977; Weiske et al., 1976; Kattenberg and Poot,1977; Ainger and Coverly, 1980; Fondu and Willems, 1971; Tafuri and Tao, 1984; Berlin,1974; Pronk et al.,1986; Graffelman, 1967; Babayan and Lehman, 1966; Ward, 1982; Lindsay,1961; Lansbergen and Schijf, 1996).
Much of the research conducted on food uses of palm /palm kernel and their fractions in foods has been done by the Malaysian Palm Oil Board. A list of their publications is accessible on the Internet. (http://www.mpob.gov.my/) or cited in the present text.
Modified Hydrogenation for Trans Fat Reduction
A considerable amount of research has been done to reduce isomerization during catalytic hydrogenation of edible oils (Hasman, 1995; List and Jackson, 2009; Beers et al., 2008, Beers and Mangus, 2004). By changing temperatures, pressure, agitation, catalyst loading, use of noble metal catalysts (platinum, palladium) and modification of traditional nickel catalysts, a significant reduction in trans acids can be achieved. Traditionally high temperatures, low pressures, moderate agitation and low nickel catalyst loadings have been employed to reduce polyunsaturates in commercial practice. However, these conditions promote trans isomerization at a rate of about 0.73% trans/IV drop. Conversely, at lower temperatures (140-170oC) and pressures of 200 lbs psi, over 55% reduction in trans can be achieved (Eller et al., 2005). However, the higher pressures would require refitting converters which normally operate at 50psi or less. Other approaches to trans reduction include hydrogenation in supercritical fluids (King et al., 2001), use of low IV oils for spreads/shortenings (List et al. 2007a), electrochemical hardening (List et al., 2007b), hydrogenation by use of nickel/platinum catalysts (Jackson et al., 2008). The use of modified nickel catalysts has shown industrial applications. Treatment of nickel supported catalysts with phosphoric acid allows a significant lowering of trans isomers during catalytic hydrogenation. At least two lines of baking shortenings employing this technology are commercially available (Higgens, 2007; Van Toor et al., 2009a,b, 2010).
Blending as Zero Trans Options
Many suppliers are offering custom blends for food applications where oxidative stability and sensory properties are primary considerations. Commodity soybean oil performs well in most applications with the exception of heavy duty frying where high temperatures promote the breakdown of the 7-8 % linolenic acid and loss of fry life. Naturally stable oils (free of linolenic acid) when blended with soybean oil to 3% or less linolenic acid, provide increased stability for frying. Blending of commodity or trait modified oils with lightly hydrogenated soybean oil can also be used as a trans fat replacement in lower fat containing foods. Such products are custom made and are available commercially.
Studies have shown that frying oils should contain about 60% oleic, 20% linoleic, and 3% or less of linolenic acid. Linoleic acid and its breakdown products contribute to the desirable fried food flavors (Warner et al., 2001). The high oleic canola, soybean, and sunflower oils (75-80% oleic acid) provide a wide range of custom fatty acid profiles for specific applications. Lui and Iassonova (2012) have reported on food uses of canola oils having varying amounts of oleic acid. DeBonte et al. (2012) reported that cereals formulated with high oleic canola oils and packaged with both high and low oxygen barriers show little deterioration after 12 days of storage at 60oC, corresponding to one-year shelf life at room temperature.
Trait Modified Oils as Trans Fat Replacements
Trait modified oils were commercialized in the early 1990’s. Low linolenic soybean oil (Hammond et al., 1972; Hammond, 1984) and mid oleic sunflower (Miller et al., 1987, Gupta,1998) and low linolenic canola oil (DeBonte et al.,1999) were not very successful due to higher costs associated with grower premiums and identity preservation (Krawczyk, 1999). However, trans fat labeling has generated new interest in the trait modified oil industry. Mid and high oleic and low linolenic soybean and mid to high sunflower, along with high oleic canola, now command about 20% of domestic consumption. A low saturate high oleic soybean oil is expected to be commercialized very shortly. In addition, an omega-3 enriched soy is nearing completion. A number of factors which have driven the development of trait modified oils include health/nutrition issues and removal of trans and saturated acids from the food supply. Since trait modified oils are essentially free of trans acids, food labels do not include hydrogenation. Trait modified oils are considered heart healthy and do not contain cholesterol. Since trait modified oils are liquids they are easily pumped and handled in bakeries and food service kitchens. Food applications include deep fat frying, pan/griddle frying, spray oils, sautéing, pan release agents, nutritional bars sauces, and dressings and some baking applications. These applications will be covered under separate sections.
Trans Free Frying Fats/Deep Fat Frying
A number of reference books covering all aspects of deep-fat frying are available and should be consulted for further information (Erickson, 2007; Gupta et al., 2004; Della Porta, 2008). Wainwright et al. (2006) reviewed options for reducing or eliminating trans acids in deep fat frying and labeling implications.
Frying fats have evolved from heavily hydrogenated soybean oil (40% trans) and were in the form of 50 pounds plasticized cubes wrapped in cellophane/plastic and packaged in cardboard boxes. Other approaches include hydrogenation to about IV 100, winterizing the oil to form a clear frying oil or hydrogenation to the same IV, and suspending hard fats to form a pourable frying shortening (Widlak, 2001).
Trait modified soybean, canola, and sunflower oil have been adopted by the food service industry as trans fat replacements. Trait modified oils are characterized by increased amounts of oleic acid, decreased polyunsaturated acid levels, and, in some cases reduced saturates when compared to commodity oils. As a result, trait modified oils have increased oxidative stability toward high temperatures used in frying. Examples now in commercial production include low linolenic, mid and high oleic soybean oils, low linolenic and high oleic canola, mid and high oleic sunflower oils. Several other trait modified oils are nearing commercialization including a low saturate/high oleic soybean oil and a stearidonic acid enriched omega-3 soybean oil (Wilkes, 2008).
An early study (Erickson and Frey, 1994) compared several trait modified soy and sunflower oils in frying tests against hydrogenated frying shortenings. Parameters investigated included foam height in the fryer, color, free fatty acids, and organoleptic tests. The results showed that the trait modified oils performed better than fluid opaque and liquid frying fats but were slightly inferior to solid cube frying fats. Other work carried out at Texas A&M University supports these findings (www.frytest.com).
Pan and Grill Shortenings
It has been estimated that 75-80% of fast food breakfast items are prepared on grills or frying pans. The source oils are soybean, coconut, palm kernel, and cottonseed. Both unsalted/salted pourable products are available and have low solid contents. Unsalted shortenings are all-purpose and are suitable for pan frying, grilling, soups, gravies, basting, and brush on dressings. Salted shortenings are seasoned but serve in many of the same applications. The solid shortenings serve as pan frying, griddle oils, and in-bun toasting. Common additives include lecithin (anti-sticking/spattering function), artificial coloring, butter flavor, silicones (reduce oxidation/oxygen barrier) and antioxidants to prolong storage life. The pourable shortenings are low in trans. Solid pan/griddle products may be low in trans but are higher in saturates since they are formulated from coconut, palm kernel and cottonseed oils (O’Brien, 2009).
Case Studies Trans Reformulation in Fast Food Chains and Laboratory Frying (trait modified oils)
Numerous laboratory frying studies have been reported. The reader is referred to them for further information (Warner et al., 1997; Warner and Knowlton, 1997; Warner and Gupta, 2003, 2005; Warner and Moser, 2009; Prevot et al., 1990; Normand et al., 2006; Matthius et al., 2009; Gerde et al., 2007; Warner and Mounts, 1993; Su et al., 2003; Kiatscrichart et al. 2003; Soheli et al., 2002; Lui and White, 1992; Miller and White, 1988).
Several frying studies from the fast food industry have been reported (Miller, 2007; Nagy-Nero, 2006; Reid, 2007). Many factors influence the choice of frying oils such as cost, availability, fry life, and consumer acceptance (Tiffany, 2007).
Other factors include no transfer of unwanted flavors added to the food; the oil should resist polymerization and not form films or residues in equipment. Frying fats tend to darken upon continued use and should remain clear for the entire fry life. Since frying oils tend to foam after extended use, resistance to foaming is highly desirable. From a health/nutrition standpoint, frying oils should be low in trans and saturated acids.
A major national chain using 160 million pounds of oil per year began the task of replacing a hydrogenated fluid shortening with a trans free alternative. Some 26 different oils and blends were evaluated for fry life and consumer acceptance. By 2004 the search was narrowed to two oils. Although both performed equally well in testing, a trait modified soybean oil was selected for test marketing in eight restaurants in New York City. Consumers were asked their reaction to the new frying oil. The results were overwhelmingly positive and the decision was reached to supply some 5500 stores with the trans free oil. A major concern was oil stability. The company uses an active filtration to polish the oil with magnesol which extends fry life and retains seasonings added to the food. The company concluded that fry life of the replacement was equal to the hydrogenated shortening it replaced. By April 2007 all stores would be serving zero trans food (Miller, 2007).
A regional chain having 1800 employees operating 40 restaurants pride themselves in offering nutritional, good tasting foods made with local ingredients. A trans free solution was sought because it was the right thing to do for their customers. They began with a trans free soybean oil packaged in 35-pound jugs. Employees were educated about trans fats and a testing was conducted in one of the chain restaurants by comparing french fries fried in trans replacement to those fried in the existing shortening. The tests showed satisfactory performance. The decision was to switch despite increased price (an additional 2 dollars per 35 lbs) with some decrease in fry life from 16 to 14 days (some as short as 7 to 12 days). It was estimated that the additional cost amounted to 6 cents per pound of oil (Nagy-Nero, 2006; Eckel et al., 2007).
Case Study Ruby Tuesday
Ruby Tuesday is a national chain with about 850 restaurants (Reid, 2007). In late 2003, a corporate decision was made to switch from partially hydrogenated soybean oil to canola oil. Two challenges were encountered — increased cost and shorter fry life. However by switching, the number of foods with trans acids decreased from 30 to approximately 10. French fries contained trans because they are purchased par fried in partially hydrogenated oil. At the time it was estimated that french fries par fried in canola would add an additional one million dollars per year. However, in the meantime zero trans frying shortenings have been marketed specifically for par/deep fat frying.
Bakery Shortenings and Applications of Liquid Oils in Baking
An extensive review of baking shortenings can be found in Ghotra et al. (2002). Troubleshooting problems in bakery/deep fat frying applications are covered by Staufffer (1996) and should be consulted for further information. The role of fats, oils, and emulsifiers in bakery applications has also been covered in recent reviews (Orthoefer, 2008; Stauffer, 2005).
Many baking applications require solid fat for functional needs — aeration, plasticity for dough products, lubricity, texture, tenderness, mouthfeel and eating properties. The use of liquid oils for bread baking has been used for many years and the use of emulsifiers and surfactants has played a major role in the switch from lard to liquid oils. Hartnett and Thalheimer (1979a,b) reported studies on the baking of sweet doughs, bread, and cakes formulated from liquid soybean oil containing emulsifiers and surfactants. In bread baking, 3% soybean oil containing 0.5% monoglycerides/ polysorbate performed as well as a commercial fluid shortening with respect to dough handling, grain, and softness. Similar results were obtained in the baking of cakes. However, the emulsifier PGMS (polyglycerol monostearate) at concentrations of 8-12% was required. This system was equal to, or better than, a commercial fluid shortening. Sweet doughs made from liquid soybean oil handled poorly, the dough was sticky, had low specific volume, and had an open irregular grain. Soybean oil with 2% added monoglycerides only slightly improved dough handling. However, soybean oil containing 1.5% monoglycerides and polysorbate 60 performed well in sweet doughs.
Kamel (1992) studied the characteristics of breads and buns made with lard and liquid vegetable oils with different iodine values. When emulsifiers are incorporated into soybean and canola oils baking performance was equal to lard/palm oils with a reduction of 30% total fat. Baldwin et al. (1972) reviewed the uses of liquid oils in breads and cakes. Cakes baked with soybean oil with the added surfactants showed excellent crumb softness and moisture retention equal to a standard hydrogenated shortening. These authors point out that the solid fat profiles of the two fat systems are markedly different; however, the temperature at which leavening power (100-110oF) of the soy/surfactant system is equal to the hydrogenated product.
Liquid Oil/Monoglyceride/Diglycerides, Oleogels in Baking Shortening Applications for Trans Reduction
The use of liquid oil/partial glyceride mixtures for trans reduction in baking are the subject of several patents (Skogerson, 2010; Doucet, 1999). The use of these systems allows a zero trans and a reduced saturate composition. Applications include cakes, cookies, danish, icings, puff pastry, and laminated products. They are powders containing 8% monoglycerides with a Mettler dropping point of 131-140oF. The products are FDA GRAS approved.
The use of oleogels/structured emulsions to provide structure and functionality in baking applications is recent technology (Marangoni and Garti, 2011). For an overview of some of the applications in this area, readers are directed to a recent review by Stortz et al. (2012).
Liquid Oil Applications in Cookies, Baked Snack Crackers, Spray Oils, Liquid Shortenings, Pan Release Agents, Pretzels, Muffins, Tortillas
Soft cookies require creaming. Traditionally, all-purpose shortenings, either hydrogenated or animal-based with added emulsifiers, have been the industry standard with a short plastic range and desired high stability. Palm and animal based soft cookie shortenings offer a trans free solution at the possible expense of increased saturates. Aini Idris et al. (1991) evaluated “biscuits” (short dough cookies) baked with 100% palm oil, blends of palm oil/butter (3/1, 1 /1), and 100% butter against a commercial cookie. Sensory evaluations were conducted for texture, flavor, and force to break as freshly baked and after three months storage. Although little significant differences in sensory tests were found among the experimental cookies, the all butter products were most liked. Force to break tests indicated that the four experimental cookies were softer in texture than the commercial product.
Baked Snack Crackers
Several well-known snack crackers have successfully been reformulated to zero trans with liquid unhydrogenated soybean oil (Klemann, 2005). Trait modified soy, canola, and sunflower oils should also serve well since they are more oxidatively stable than commodity unhydrogenated soy containing 7-8% linolenic acid.
In addition to extensive food service and home uses, spray oils are used in the cracker baking industry. Crackers, croutons, and crisps are often sprayed with a thin layer of oil to serve as a moisture barrier in order to protect the product from flavor and textural deterioration. Traditionally, hydrogenated soybean oil (IV 70-80) or coconut oil have been used for spraying the crackers. The former is high in trans while the latter is very high in saturates. Thus, trait modified soy, canola, and sunflower oils should perform well in spray applications. Limited published data confirm that low linolenic soy and mid oleic sunflower oils were equal to hydrogenated controls in cracker spray tests (Erickson and Frey, 1994).
Pan Release Agents: Zero Trans Options
Bread is baked in loaf pans arranged in racks and then inverted on exiting the oven. Thus, it is imperative that loaves release readily from the pans (Weiss, 1983). A number of pan release agents have been described in the patent literature (Carey, 1974; Gawrilow, 1975a,b; Hanson, 1980). Since they must be easy to apply they are usually in liquid form. However, solid stick pan lubricants have also been described in the patent literature (Mahler and Doumani, 1977).
Stick pan lubricants can be formulated from liquid (unhydrogenated) vegetable oil, lecithin, hydrogenated fatty acid glycerides or wax in the following proportions: 30-45 parts oil, 5-20 parts lecithin, 40-60 parts wax/fatty acid glycerides. A typical formulation consists of 50% hydrogenated tallow, 15% double bleached lecithin and 35% liquid soybean oil. Other base vegetable oils include those liquids (approved for food use) at room temperature. Since they are applied by hand pressure, an effective layer of lecithin is deposited on the pan so food does not stick. In addition to zero trans oils as bases, other common ingredients include aluminum stearate, lecithin, partial glycerides, animal and vegetable waxes, polysorbate esters and flours. Trait modified oils should perform well in pan release products. Although more costly than commodity oils they provide added oxidative stability.
Pretzels, Muffins, Tortillas
Traditionally, pretzel dough has been formulated with hydrogenated soybean oil. Reformulation to zero trans can be achieved by switching to liquid unhydrogenated oil (Manirath et al., 2006). Pretzels normally contain about 2% fat needed for tenderness, mouthfeel and structure/strength. Many home recipes call for vegetable oil in muffins (either commodity or trait modified); soybean, corn, canola, cottonseed oils furnish a zero trans solution. Flour tortillas also contain hydrogenated oils or animal fats because of improved machinability and reduction of dough stickiness. However, trans fat labeling has stimulated interest in 100% liquid oil in tortillas despite the possible sticking together when stacked in packages. Liquid oils provide not only a trans free solution but eliminates the heating of the fat before usage. The reader is referred to a recent patent describing the use of liquid oil in tortilla manufacture (Gerardus et al., 2009).
Trait Modified Oils in Fluid Shortenings
Fluid shortenings have been used for many years in the baking and food service industry (Norris 1975, 1976). However, fluid shortenings have never been well received in the retail market place despite a large amount of research and development by the oil processing/food industry (Howard and Koren, 1965; Linteris, 1959; Andre and Going, 1957; Brock, 1959; Cross and Griffin, 1956; Houser,1961). Proctor and Gamble marketed such a product (SWIRL) but it was discontinued after a short time (Weiss, 1983). Typically fluid shortenings have been formulated from either an unhydrogenated soybean oil with a completely hardened soybean oil (IV + 5 or less) or a hydrogenated oil (IV 90-100). The hard fat is in a beta stable form suspended in the liquid portion (Widlak, 2001). The solid portion contains 2-6% hard fat. Applications for these products include frying, grilling, toppings, and popping. Silicone and antioxidants are normally added to frying oils to stabilize against foaming and oxidation. Grilling, toppings and popping oils may contain antioxidants, lecithin and colors, salt and coloring, and flavor components. Bread and cake fluid shortening are formulated from liquid oils (IV 90-130) with the solid portion furnished by partial glycerides and their esters, lecithin, and polysorbates. Antioxidants are added for oxidative stability.
Shortenings prepared in this manner can be used for yeast raised bakery products (Norris, 1976). Since trait modified oils show increased oxidative stability, hydrogenation may not be required and would serve well in trans free fluid shortenings for the baking/food service industry market (Orthoefer, 2005).
Palm Based Baking Shortenings
As mentioned previously, palm-based shortenings have been increasingly popular as a trans fat solution for many foods and baking shortenings since they furnish solid fat needed for functionality and are strong beta prime crystal formers (desirable in shortenings and spreads). Fully refined, bleached and deodorized palm serves as an all-purpose baking shortening after plasticization. However, while very low in trans, such shortenings contain about 50% saturated acids. Palm kernel oil and its fractions have uses in baking shortenings, confections, and spreads but are very high in saturates. Palm and palm kernel oils are particularly well suited to formulate products low in trans and saturates when combinations of fractionation, interesterification, and hydrogenation and blending are combined. Fractionation of palm/palm kernel oils yield liquid oleins (lower in saturates) and a stearine fraction higher in saturates. These can be further fractionated to yield super oleins and stearine. Further fractionation yields even harder fractions. Very hard stearines form structuring fats capable of holding large amounts of liquid oil in emulsified systems and are particularly useful for the manufacture of margarines and spreads (Sahasranamam, 2005). Blending of structural fats (5-15%) with liquid oils (85-95%) such as canola and high oleic canola and soybean oils yields melting points and solid fat matching those of soft spread oils. The hard structuring fats (20%) can be interesterified with soybean oil (80%) to produce a product with physical properties matching an all-purpose baking shortening. Thus the use of palm stearines in conjunction with liquid oils allows a trans free solution with minimal increases of saturated acids.
Both unemulsified and emulsified palm based shortenings are commercially available. Non emulsified shortenings are used primarily for frying and are offered in plasticized cubes, in bulk, and specially fats for donut frying. Donut frying oils are formulated to reduce oiliness and assure adhesion of frosting and glazes. Palm based emulsified shortenings are formulated with mono/diglycerides, polysorbate 60 esters, (polyglycerol monostearate) PGMS, and lecithin, depending on the application. Cake icing, creamy icings, and scoopable icings normally contain mono/diglycerides and polysorbate esters as emulsifiers. Cake shortenings designed to give enhanced aeration are emulsified with mon/diglycerides. Palm based shortening specially designed for packaged cake mixes contain mono/diglycerides, PGME, and lecithin. Other palm based shortenings are formulated with the foregoing emulsifier system and are designed for low-fat cakes.
Palm based coating fats are available for a wide variety of baking applications—cookies, donuts, and cakes. Firmer coating fats for baked goods and snack bars, as well as rapidly crystallizing shortenings for baked goods and bars, are available commercially. Palm kernel based fats for hard coatings, i.e. confections and snack bars, are likewise available. These products are lower in saturated fat and are designed to be bloom free for the shelf life of products. They are also compatible with both palm and hydrogenated shortenings.
Performance Testing of Palm Based Baking Shortenings
In 2006, the American Institute of Baking presented a study of the performance of zero trans baking shortenings at the AHA trans fat conference held in Washington, DC (available on the internet) (Strouts, 2006, www.americanheartassociation.com). A summary of the entire meeting was published in the AHA Journal (Eckel et al., 2007).
Although many of the problems encountered in early baking applications with trans fat replacements have probably been solved, the fact remains that trans fats do not always behave like their replacements (Loh, 2006). Differences in functionality include loss of aeration, volume, appearance, plus greasy/oily handling may occur. Processing issues can include achieving specific gravity of batters and cream fillings which leads to package fill issues, curdling of batter emulsions, loss of sheet forming capabilities and disruption of dough film formation. Flavor and finished product quality issues are off-flavors in high-fat products like cookies and donuts. Eating quality may be affected when the shortening leaves a coating effect in the mouth from higher melting triglycerides. Flavor development may also occur during the frying process.
Hydrogenated bakery shortenings (trans containing fats) are/were produced with specific melting points and solid fat index/solid fat content, depending on their final end use (Johnson,1999). As a result, drop in solutions for baking were not always successful (Loh, 2006). Both palm based and interesterified baking fats may contain higher amounts of saturated triglycerides that crystallize differently than hydrogenated fats. Palm oil has a tendency to crystallize slowly with the net effect that products may have a smooth creamy texture after passing through a votator; however, after storage, they become harder. This phenomenon is known as post hardening and has been attributed to diglycerides or the presence of POP (where P is palmitic acid, O is oleic acid) (Sudin et al., 1991). Since interesterification greatly alleviates the problem, the latter seems more likely. Processing conditions during the chilling and crystallization of emulsions in scraped surface heat exchangers and pin workers may also contribute to post hardening of palm based margarines. In pilot plant studies emulsion temperatures of 10oC above the fat’s melting point, flow rates of 45kg/hour through the A unit, a super cooling temperature of 20oC, and pinworker (B unit) speeds of 200 rpm are optimal for controlling post hardening and delays of trans formation from the beta prime to the higher melting beta crystal habit (Mat Sahri and Aini Idris, 2006). Kirkeby (2009) reported full scale (1000kg/hour) data for residence times in scraped heat exchangers, pin workers, and resting tubes. This, in turn, determines product throughput and properties of finished margarines and spread.
Other studies on formulation of zero trans soft soybean margarines from interesterified oils indicate that solid fat index is not reliable in predicting spreadability (List et al., 1995, 2001). Less solid fat is needed for interesterified margarines compared to hydrogenated oils. Typical SFC values at 10o, 21.1o and 33.3oC are about half that of similar products formulated from hydrogenated oils.
Performance of Palm Based Baking Shortenings (zero trans)
The majority of baking studies with palm oil shortenings has been done in the laboratory (Aini Idris et al., 1987, 1988, 1989). Zero trans shortenings prepared from hydrogenated palm oil, palm stearin, blended with cottonseed, low erucic rapeseed, cottonseed and soybean oils in various proportions were evaluated in the baking of madeira cakes, chosen because they are low in fat and most sensitive to the properties of the shortening. A hydrogenated shortening was used as a control. The results showed that all of the 10 formulations yielded excellent specific cake volumes and creaming performance exceeded that of the control. They concluded that good creaming performance does not necessarily ensure good baking performance. Interesterified palm olein (100%) was judged to be superior for cream fillings and baking.
Dogan et al. (2007) studied the effects of interesterified and simple blends of palm/cottonseed oil shortenings on cake quality. Batter density, creaming, crust color, crumb color and sensory were evaluated against a hydrogenated emulsified baking shortening. It was concluded that levels of 25-50% palm oil in the interesterified blends gave good aeration and creaming properties and cakes with excellent crumb grain, moistness, and sensory properties, making a suitable replacement for hydrogenated shortenings. Ranhotra (1993) reported cake volume data on six palm oil formulations which were compared to standard shortening. All gave results ranging from 95-99%.
Waheed et al. (2010) reported a baking study in which sugar cookies were evaluated with interesterified palm/cottonseed blends against a hydrogenated baking shortening. The cookies were evaluated for width, height, color, taste texture, and overall acceptability both as fresh and after storage at ambient temperatures up to 45 days. Little differences in spread factors were noted after 45 days storage. Control shortening showed the best overall acceptability closely followed by the 50/50 interesterified blend of palm/cottonseed oil. All cookies showed a gradual deterioration in storage with respect to overall acceptability.
The American Institute of Baking presented performance tests in which commercially produced palm oil based shortenings were compared against a hydrogenated shortening in cookies, crackers, puff pastry, donuts, and pie crusts (Strouts, 2006). The results showed that compared to a standard hydrogenated shortening, palm based fats performed as well, or better, in these applications. In 2003, a major oil supplier marketed a line of zero trans baking/spread fats based upon enzymatic interesterification of liquid and completely hydrogenated stearines (Anon., 2004; Lee, 2008). The process involves blending liquid soybean oil with soybean or cottonseed stearines and then passing the mixture through a series of four reactors containing a 1 to 3 specific enzyme where rearrangement occurs. The technology is versatile as the physical properties (melting point, solid fat content) of the rearranged fat can be controlled by the amount of hard stock in the simple blend. For example, an 85%/15% blend yields margarine/spread oils while increasing the hard stock to about 30% resulting in an all-purpose baking shortening which yields about 40% fats suitable for puff pastry.
Performance Testing of Interesterified Zero Trans Baking Shortenings
Enzymatically interesterified shortenings (soybean, soy plus cottonseed) were compared to an all-purpose baking shortening prepared from hydrogenated soybean oil, a palm based shortening, a hydrogenated soybean/cottonseed blend in baking tests including sugar cookies, high ratio cakes, and pie shells (Tiffany, 2008).
Parameters tested for sugar cookies included texture analysis (force to break), stack height, width, and wicking. High ratio cake testing involved texture, specific gravity, and height. Pie dough tests included texture analysis and wicking.
The sugar cookies prepared from the five shortenings all showed comparable stack heights with little differences. However, the all-purpose shortening showed the smallest spread and force to break after three days. Wicking or the seepage of fat showed little difference between the five shortenings; however, the interesterified soy shortening showed the least amount of wicking. The spread factor (width /height) was very similar for all shortenings tested.
High ratio cakes were tested for texture (grain), force to break, height, and batter specific gravity. The all-purpose shortening produced a cake with the coarsest open grain while the interesterified soy and the soy with added cottonseed oil (post-interesterification) had a closed fine grain. Although the differences were small, the hydrogenated shortening showed the highest batter specific gravity, but the interesterified soy oil shortening had the best cake volume height. Texture or peak force measurements after one and three days indicated that the interesterified soy oil shortening was equal to the hydrogenated control, indicating equal cake softness. The pie dough evaluations showed that the interesterified soy shortening had the lowest amount of wicking and the lowest peak force required for breakage, both of which are highly desirable. In summary, limited data suggests that interesterified zero trans baking shortenings perform in a wide variety of applications as well, or better than, the hydrogenated fats they replaced.
Trouble Shooting Trans Free Baking
Standard baking tests employed by the baking industry are outlined in the Official Methods of the American Association of Cereal Chemists. Many of these methods are designed to evaluate flours rather than fats and oils. Typically, cakes are formulated from “bakers” hydrogenated emulsified shortening while cookies and pies require non emulsified all-vegetable hydrogenated shortenings for evaluation of finished baked goods. Thus substituting trans free shortenings for hydrogenated fats posed problems for bakers, many of which were overcome by making adjustments to the baking process and handling/storage of trans replacements.
Common complaints included: shortenings were too hard or too soft; margarines had off flavors; and loss of quality with time. Cookie doughs were too hard when chilled, too crisp, excessive spreading, macaroons too dense. Icing/butter creams had off flavors and colors, breakup of stored icing, icing too soft or too stiff. Donuts were oily, and “off-tasting”.
Problems (creaming/off flavors/storage life/stiff doughs/cookie texture/spread/icing performance/donut frying fats):
- Palm oil shortenings tend to be harder in winter and softer in summer leading to difficult creaming properties. Palm based shortenings tend to be sensitive to temperature changes. During the winter months, storage in warmer conditions is advised. On the other hand, storage in summer requires a cooler spot to get the desired firmness.
- Palm based baking margarines can, on occasion (although rarely), develop slight off flavors (typical of tropical fats) in sweet rolls and pound cakes. A solution might be found in a different brand or the addition of butter flavor to the recipe.
- Complaints that trans fat replacements do not last as long as the hydrogenated products have been expressed. The latter can often be stored for a year compared to 6-9 months for the new margarine or shortening. Oftentimes, the supplier gives storage instructions to ensure preservation of keeping qualities. Other options include the purchase of smaller quantities more frequently.
- Some bakeries pre-make the dough in advance of the next day needs, followed by resting in a cooler. As a result, the dough becomes too stiff to roll out. Palm based margarines are temperature sensitive, allowing the chilled dough to sit at room temperature long enough to become soft enough to work. However, doughs should not be allowed to sit at ambient temperatures for more than 2 hours.
- Sugar cookies become too crisp with trans fat replacements. Adjustments to baking time and temperatures, a slight reduction in baking time or a reduction in baking temperature may solve the problem. Other options include replacement of part (up to 25%) of the granulated sugar with liquid sweeteners. However liquid sweeteners may cause increased browning. Thus, by varying bake time, temperature and liquid sweeteners, chocolate chip cookies may spread too much with the new shortening. This can be solved by baking 25 degrees higher than usual to “set” the cookies earlier in the baking cycle and reduce baking time. Another solution involves substituting some of the flour with high gluten bread flour (up to 20%).
- Icings made with alternative shortenings turn brown in color and have an off-flavor. This problem is common in some palm based icing shortenings. Different products may be different in flavor and whiter in color.
- Freshly prepared butter creams are excellent, but overnight loss of volume and “oil-off” occurs. This can be traced to improper emulsification of the shortening. All-purpose shortening may not be emulsified at all. All icing shortenings are emulsified but not all perform the same way. Options include use of different brands, adding extra emulsifier (as directed by the supplier), or making smaller batches and using the same day.
- Soft/stiff icing problems can be solved by either refrigeration of soft icing before use or adding up to 10% of extra powdered sugar. Stiff icings result from cool temperatures. Tempering at room temperature for not more than two hours, or the addition of up to 5% water are helpful.
- Over-mixing may cause breakdown of icings. Softer trans free sandwich cookie fillings may need a longer set time before crowning.
- Donut frying oils may lead to greasy bitter tasting donuts. Use of fresh oil at the proper frying temperature may solve the problem. Switching to a different brand of palm based or palm free/reduced trans shortening may be an option (Anon. 2012).
Zero Trans Margarines and Spreads
Health and nutrition issues over trans and saturated acids have greatly impacted the spread market. Consumption in the US is down about 50% from the peak years of the mid-1990’s. A number of factors are responsible, including government dietary guidelines which have become increasingly critical of dietary fat. This coupled with the “poisoning of America” campaign in the mid-1980’s prompted the low-fat food craze soon to follow. The spread industry began a concerted effort to reduce both trans and saturated acids from products. By 1999 a survey showed that a marked decrease (about 55%) in trans fatty acids occurred in a short period of time (List et al., 2000). Social issues have also brought decline to the domestic spread industry. Eating habits have changed from the traditional breakfast of toast, etc. to a trip through the drive-through. While convenient, this is as unhealthy as a touch of margarine on a piece of toast, muffin or bagel. In addition, numerous press releases on the potentially harmful effects of trans and saturated fats have educated consumers to read food nutrition labels, avoid trans and saturated fats, and choose heart-healthy products. Also, “hydrogenated, interesterified and tropical oils” are portrayed as unhealthy as well as those products advertised as having less saturated fat than butter.
Technologies to prepare improved margarine and spreads have been available for many years (Melnick, 1960; Gooding, 1963; Seiden, 1971). An excellent summary of the patent literature up until 1974 has been published (Gillies, 1974). However, early focus was not on the removal of trans and saturated acids but increasing the amounts of essential fatty acids. Zero trans margarines were first commercialized in Europe during the 1960’s under the acronym “BECEL” (Blood and cholesterol lowering) which are still popular in Europe and Canada (but marketed under different brand names) (Nieuwenhuis, 2000). The original formulation consisted of interesterified palm fats and low IV hard stocks as the solid portion and liquid sunflower oil to furnish high levels of linoleic acid. Since only 8-10% hard stock was needed BECEL contained low trans, low saturates and increased essential fatty acids (Graffelman, 1967).
The first US generation of zero trans soft margarines and spreads were formulated from lightly hydrogenated oils blended with liquid soybean, canola, corn, and to a lesser extent, olive and palm oil and its fractions (List and Pelloso, 2007). Consumers were educated that hydrogenation on labels was not healthy despite meeting zero trans requirements under the 2003/2006 Federal mandates. Today most soft tub spreads are reformulated with the same liquid oils but solids are now furnished by tropical oils (including palm and palm kernel and their fractions).
Stick products (80% fat) have proven to be difficult to reformulate because they must have sufficient solid fat for storage under ambient conditions. Typically, stick products contain 1.5-2.5 gram trans fat per serving. However, retail stick fat products are marketed as zero trans and require refrigeration.
A recent study reported that palm stearin (PS) (IV20-40) as well as palm kernel olein can be used to formulate trans free block/stick margarines. By blending the hard stocks with varying amounts of liquid sunflower oil, margarine with sufficient solid fat content to ensure spreadability at low temperatures, structure (resistance to oil off), at ambient temperatures, and complete melting at body temperature, are obtained. Pastry margarines can also be produced with the long plastic range needed for rolling dough and folding needed for the flaky texture of the final baked goods (Mat Sahri and Aini Idris, 2010).
Kirkeby (2008) reviewed formulation of low/zero trans in the European industrial and retail sectors. Industrial products (including soft table/table margarines) contain 4-8% and 10-13 % trans respectively. Cake, puff pastry and pumpable liquid shortening contain 8-26% trans because partially hydrogenated palm (mp 42oC) and vegetable oils (mp 34oC) (25-75%) are included for solid fat in the formulations. Liquid oils and/or palm and coconut oils account for the remainder. The trans contents of these formulations are similar to products produced in the US by blending hydrogenated base stocks with liquid oils and/ or hard stocks (fully hydrogenated, low IV (5-10) from soybean, cottonseed oils). The trans content of the above products can be reduced to about 3% by substituting palm stearin interesterified with coconut oil (25-80%) for solid fat. Both types of products are designed for usage temperatures of 5o, ambient, 25o, or 30oC. It should be pointed out that small amounts (1-2%) of trans isomers are formed during bleaching and deodorization of fats and oils. These isomers are formed from polyunsaturates rather than industrial hydrogenation. In the US only C18 trans monoenes acids are included for nutrition labeling purposes.
The European spread/margarine market amounts to about 2,500,000 metric tons or 5.6 billion pounds per year with Germany, the UK, Poland, the Netherlands, and Belgium accounting for about 65% of production in EU 27 countries. Total consumption in the EU countries has remained static over the 2003-2010 timeframe. However, in 2010 Germany, Austria, France, and Belgium imported about 65% of the spreads consumed. The export market for 2010 shows that Belgium, the Netherlands, and Germany furnished about 75% of spreads consumed in the EU. The consumption in the 27 EU countries amounts to about 5.6 billion pounds per year. With a population of 502 million, per capita consumption amounts to about 10 pounds per year. On the other hand, the US (population 311 million) consumption of spreads in 2010 was about 1.2 billion pounds or a per capita of 3.4 pounds. According to Korver and Katan (2006), the European spread market has prospered due to an early awareness of the possible adverse effects of dietary fatty acids, their removal from spreads, coupled by modification of technology developed in the 1960’s in which hard stocks were blended with liquid sunflower oil (Graffelman,1967). The old technology involved hard stock with 16.5% saturates and 10.5 % trans yielding 27% saturates plus trans per 100 grams fatty acids. Trans free hard stocks in the reformulated products contained less than 1% trans and 21-22% saturates and oil binding properties were similar. Further information can be found in a 2005 review (Upritchard et al., 2005). Thus, modern technology has provided removal of trans fats from spreads with decreased saturates and are heart healthy as well.
Spread and margarine oils are formulated for functionality, including spreadability, resistance to oil-off and mouthfeel. Typically, solid fat contents at 50o, 70o and 92o F, along with melting point define spread functionality. An early report outlining the physical properties of trans free retail spreads indicated that oil-off was a potential problem due to their lower melting points (25-28oC) compared to hydrogenated counterparts (31-32oC) (List and Pelloso, 2007b). Despite having a trans free claim and fortified with cholesterol lowering sterols these products are expensive and command only a minor share of the US spread market.
Unlike all-purpose shortenings, bakery margarines are emulsified and serve in a number of bakery applications. Generally, they fall into five categories including table grade, baker’s margarine, roll-in margarines, puff pastry, and specialty roll-in (Johnson, 1999). Prior to trans fat labeling, these products were formulated from hydrogenated oils with specific solid fat indexes and melting points according to the specific application. Bakery margarines can be substituted for butter as well as all-purpose shortening in most applications with the exception of donut frying. An excellent review of bakery margarines and applications has been published by Johnson (1999) and Wainwright (1999) who reviewed oils and fats for the baking industry.
Both low trans free baking margarines are commercially available and are formulated with either hydrogenated (from a proprietary process) (Higgens, 2007) or tropical oils. Both lines of products show reduced trans, minimal increases in saturates and the tropical fats do not carry hydrogenation on the label, nor does the hydrogenated fats carry a tropical oil label. Both lines of bakery margarines are reported to offer an 80% reduction in trans and a 33% reduction in trans plus saturates compared to standard bakers grade products. The hydrogenated products reportedly can be used as a drop in solution for icings, fillings, cookies and danish. A beta-prime stable, low saturate/low trans all-purpose shortening has been patented (Scavone, 1995).
The tropical based fats are specifically designed for croissants, roll-in applications, biscuits, and emulsified doughs. Palm based fats for frozen bread bakery doughs have been tested in the laboratory and found to be equivalent in height (before thawing and baking), bread volume and sensory evaluation compared to a commercial product designed for baking of bread (Ruihong et al., 2008).
The performance and formulation of trans free roll-in margarine has been reported (Kanagaratnam et al, 2008). Palm, palm stearin (14-44 IV) palm kernel oil palm kernel stearin and interesterified palm/kernel blends were processed into margarine emulsions (82% fat) and then processed in the pilot plant consisting of three A units and a single resting tube. The margarines were tempered at 20oC for four days. The melting point of the experimental margarine was 43oC compared to 42-45oC for commercial (hydrogenated) products. Optimum blends matching the hydrogenated margarines consist of palm stearin IV 20 or less at levels of 15-25 % (promotes fast crystallization at temperatures below 30oC and provides structure above 30oC). Medium melting fats (palm oil palm stearin (IV35), palm kernel stearin interesterified) at levels of 30-50% ensure good mouth melt properties. Liquid oils and palm olein, palm kernel oil and olein are used at levels of 25-40% to obtain solid fat profiles according to customer needs. Texture analysis showed that the roll-in margarine is similar to that of play dough having the unique ability to be formed and reformed according to stress applied. Thus in roll-in pastries the fat forms even, continuous layers during sheeting and lamination. Flexibility is crucial to the performance of roll-in fats through formation of even layers of continuous fat needed for even puffing up during baking. If roll-in fats are too hard or soft the sheeting and lamination steps preclude their use as hard fats resist sheeting by lumping or tearing the dough. Similarly, soft fats cannot stand stress during sheeting and may form pools of oil which could seep out of the dough during sheeting.
Retail trans free baking shortenings
Crisco all-purpose baking shortenings have been popular for over a hundred years (List and Jackson, 2007, 2009). Originally it was formulated from hydrogenated and liquid cottonseed oil, followed by hydrogenated and liquid soybean oil. In 2003, a portion of the Crisco brand was reformulated to zero trans. By 2006 the entire Crisco brand became trans free. The formulation consists of fully hydrogenated hard stocks and liquid sunflower oil. Orthoefer (2005) described the formulation of zero trans shortenings by blending soybean, cottonseed or palm stearines with high oleic canola oil, either as simple mixtures or after interesterification. These shortenings have a wide plastic range and should perform well in most baking and/or frying applications.
Animal fat based all-purpose shortenings are popular retail items and perform well in commercial baking/deep fat frying (Kincs, 1985; Woerfel, 1960) and are low in trans acid content. In 2010 the food use of animal fats (lard, tallow) amounted to 1530 million pounds with a per capita consumption of 4.9 lbs. In the same year, butter consumption was 1510 million with a per capita of 4.9 lbs. Per capita consumption of all food products in 2010 was about 82 lbs. Thus, the 9.8 pounds of animal fats account for nearly 12% of US per capita consumption of fats.
In summary, the food, oil processing, and agribusiness sectors have overcome many technical issues in order to bring healthier products to the market place in spite of working with only a few fats and oils, i.e. palm, soybean, canola, sunflower, corn, cottonseed, and animal fats. Only time will tell if the expense and time required to meet labeling regulations are merited.
Frying Studies zero trans trait modified and commodity oils
A number of reference books covering all aspects of deep fat frying are available and should be consulted for further information (Erickson, 2007; Gupta, 2004). Among the many topics covered are the chemistry, safety of used frying oils, selection for specific end uses, analytical methods for measuring deterioration, and performance. Wainwright et al. (2006) reviewed options for reduction/elimination of trans fat in deep fat frying and labeling implications. Tiffany (2007) presented an excellent discussion of options available for deep fat frying. Della Porta (2008) covers many aspects of snack food manufacturer and contains much practical information.
A number of frying studies have been reported on trait modified soybean, canola, and sunflower oils. By and large, most have been conducted on the frying of French fried potatoes. The usual protocol involves frying for 13 eight hour days with chemical and sensory tests on the frying oil and the fried foods. Common chemical tests include free fatty acids, color, total polar compounds, peroxide value, and anisidine value. Sensory tests are conducted by a trained taste panel who evaluate the food for appearance, color, crispness, greasy flavors, and like/dislike. In most studies, a hydrogenated vegetable oil frying shortening serves as a control. A study conducted by Texas A&M University is summarized as follows with five categories of results:
- Category 1 – Fat %
- Category 2 – Total polar materials (% after 300 fryings over 13 days of frying)
- Category 3 – Color and sensory properties across 1 to 13 days of frying
- Category 4 – Food to oil ratio (pounds of fries per pound of oil)
- Category 5 – Appearance/color (like/dislike) rated on a scale of 1-8 where 1=dislike extremely and 8= like extremely. See Table 1.
The results suggest that high oleic sunflower and high oleic canola have the best fatty acid composition with regard to saturated fat content and where saturated acid content is critical to labeling, these oils would be good choices. However, both demand premium prices over commodity oils. It is interesting to note that European recommendations for the discarding of frying fats is 24% total polar compounds (TPC). All the oils listed in Table 1. fall considerably below 24% (i.e. 7.8 - 16.7 TPC). Low linolenic soybean oil showed the highest amount of TPC. It is used by Kentucky Fried Chicken to supply 160 million pounds to 5600 national outlets (Miller, 2007).
A regional chain having 1880 employees operating 40 restaurants pride themselves in offering nutritional good tasting foods made with local ingredients. Thus a trans free solution was sought because it was perceived as the right thing to do. They began with a trans free soybean oil (presumably low linoleic soy) packaged in 35-pound jugs. Employees were educated with respect to trans fats. A test was conducted in one of the chain restaurants by comparing French fries fried in the soybean oil against the existing hydrogenated shortening. The tests showed satisfactory performance so a decision was made to switch, despite the increased cost (an additional 2 dollars per 35 pounds and some decrease in fry life. The hydrogenated frying shortening had a fry life of 16 days compared to 14 days, some as short as 7-12 days. Overall it was estimated that the additional costs amounted to 6 cents per pound of oil (Nagy-Nero, 2006; Eckel et al., 2007).
In late 2003, a corporate decision was made to switch from a partially hydrogenated soybean oil frying shortening to low linolenic canola oil. Ruby Tuesday is a national chain with about 850 restaurants. Several challenges were encountered which included additional cost and shorter fry life. However, the number of foods containing trans fats decreased from 30 to 10. French fries were among those containing trans fats because they were purchased as par fried in hydrogenated fats. At that time it was estimated that par frying in canola oil would add an additional cost of 1 million dollars per year. In the meantime, zero trans frying shortenings have been marketed specifically for dual purpose par/deep fat frying use (Reid, 2007).
Numerous laboratory frying studies have been reported by scientists in government and academia (Warner et al., 1997; Warner and Knowlton, 1997; Warner and Gupta, 2003, 2005; Warner and Moser, 2009; Prevot et al., 1990; Normand et al., 2006; Matthius et al., 2009; Gerde et al., 2007; Warner and Mounts, 1993; Su et al., 2003; Kiatscrihart et al., 2003; Soheli et al., 2003; Lui and White, 1992; Miller and White, 1988). Taken as a whole, these reports confirm that trait modified soybean, canola, and sunflower oils perform well in deep fat frying applications.
Erickson and Frey (1994) reported a study where low linolenic soybean oil and mid oleic sunflower oil were tested in deep fat frying applications against heavy duty hydrogenated frying fats. The trait modified oils performed well in frying and as spray oils for crackers.
Trait modified oils in high stability applications
Traditionally high stability oils have been made by hydrogenation and fractionation of commodity oils and are a small portion of the edible oil market (Lampert, 2000). However, they are quite useful despite high levels of trans fats and high costs. Because of increased oxidative, stability trait modified oils have great potential for high stability applications (nut roasting, flavor carriers, moisture barriers, viscosity modifiers/confections, gloss enhancers, pan release agents, spray oils, antidusting/anticaking, and products requiring long shelf life.
- heat transfer,
- solubility of minor additives,
- keeps moisture from leaving or entering products,
- compatibility with other fats,
- adherence to food surfaces,
- provides lubrication,
- prevents clumping and sticking of particulates, and
- preserves product quality for extended shelf life.
A recent report indicates that high oleic canola oil performs well in breakfast cereals. A high canola oil (80% oleic acid) was tested against commodity soybean oil in which the cereals were packaged in high and low oxygen barrier bags and stored for 12 days at 60oC. The oils were extracted and peroxides were determined. In both high and low packaging, the soy oils showed extensive oxidation (PV 35-40) compared to the canola oil (PV negligible) (DeBonte et al., 2012; Liu and Iassonva, 2012). The storage conditions are equivalent to one year at room temperature.
Liquid oil (unhydrogenated zero trans) as trans fat replacements in various food applications
Commercial bakers have used liquid oils for many years in bread, rolls, buns and cake mixes. When emulsifiers and/or surfactants are added to liquid oils, a liquid shortening results and thus provides aeration, structure, and texture to the baked goods. In addition to providing these functional requirements, the fats can be easily pumped and metered into the baking process (Hartnett and Thalheimer, 1979).
Liquid oils perform well in fluid shortenings consisting of a suspension of beta tending soybean oil hard stock, (IV 5 or less) in a liquid oil which may or may not be hydrogenated. When hydrogenated oils are used the iodine value is reduced from 130 to about 100 (for added oxidative stability) (Andre and Going, 1957; Herzing, 1996; Mitchell, 1950; Holman and Quimby, 1950). However, the fluid shortening will contain about 20% trans acids and an increased saturate content. Although liquid shortenings based on a trait modified liquid oil/hard stock are not yet available, they would be an oxidatively stable zero trans solution for baking applications. The same principal has been used to formulate solid zero trans shortenings for the retail sector. The 100 plus year old Crisco is now trans free with lipid components consisting of high oleic sunflower oil and soybean hard stock. The difference in processing stems from use of scraped surface heat exchangers and pin workers to crystallize and solidify the product, whereas the fluid shortenings are allowed to crystallize slowly while under agitation (Widlak, 2001).
Pan and grill oils
It has been estimated that 75-80% of fast food breakfast items are prepared on grills or in frying pans. Source oils include soybean, coconut, palm kernel and cottonseed. Both salted and unsalted pourable products are commercially available and have low solids content. The unsalted are considered all-purpose for pan frying, grilling, soups, gravies, basting, and brush on dressings. Unsalted shortenings are seasoned but serve in many of the same applications. Zero trans products are available to the food service sector including butter/garlic flavors. They are formulated by blending liquid and tropical oils. Solid shortenings are commonly used as griddle oils in pan frying and bun toasting. Common additives include lecithin (antisticking/spattering function), artificial coloring, butter flavors, silicones (reduce oxidation/oxygen barrier) and antioxidants to prolong storage life. The pourable products are low in trans acids as are the solid ones. However, since the solid products are formulated from coconut, palm kernel, and cottonseed oils, they may be higher in saturated acid content (O’Brien, 2009).
Bakery shortenings and applications of liquid oils in baking
Extensive reviews of baking shortenings can be found in Ghotra (2002), Woerfel (1960), Weiss (1983), Johnson (1999), O’Brien (2005). Trouble shooting in bakery/deep fat frying is covered by Stauffer (1996). Emulsifiers are important components of bakery shortenings and are covered in detail by Stauffer (2005) and Orthoefer (2008).
Hartnett and Thalheimer (1979) reported studies on the baking of sweet doughs, bread, and cakes. Bread baked with 3% liquid soybean oil containing 0.5% monoglycerides/ polysorbate concluded that performance with respect to dough handling, grain and softness was equal to a standard fluid shortening. Similar results were obtained in cakes but the emulsifier PGMS (polyglycerol mono stearate) was needed at concentrations of 8-12%. Sweet doughs made from soybean oil handled poorly (sticky, low specific volume, and open irregular grain). Monoglycerides at 2% had little effect but 1.5 % with polysorbate 60 performed well in sweet doughs.
New technologies for trans fat reduction in baking fats
The use of liquid (zero trans) oils partial glycerides is the subject of several fairly recent patents (Doucet, 1999; Skogerson, 2010). The use of these systems allows a zero trans and a reduced saturate composition. Applications include cakes, cookies, danish, icings, puff pastry and laminated doughs. The fat systems are powders containing 8% monoglycerides with Mettler dropping points of 131-140o F. The powders are FDA GRAS approved for food use.
Oleogels/structured emulsions represent a new technology for trans/saturated fatty acid reduction (Marangoni and Idziak, 2008; Marangoni and Garti, 2011). The gels are produced by shearing water, liquid oil, and partial glycerides. As such they are trans fat-free and contain less saturated fat than hydrogenated or interesterified baking shortenings. Studies have shown that oleogels perform well in a variety of food products including cookies, cakes, pie shells, muffins, pizza and frozen doughs. In addition to a reduced saturate/zero trans option, the process of manufacturing the gels is simple, employs cheap readily available components (liquid commodity oils), as well as providing functional advantages in different food products.
Liquid oil applications in other foods: hard cookies, baked snack crackers, pretzels, muffins, tortillas
Soft cookies require creaming and as such, all-purpose shortening (either hydrogenated or animal fat based) with a short plastic range and high stability have been the industry standard for many years. Thus, cookie shortenings tend to contain trans and saturated fats and perhaps cholesterol. Palm and animal based shortenings are trans free alternatives (Weiss, 1983).
Hard cookies require fat for lubrication. Thus any formulation calling for vegetable oil can include any commodity or trait modified oils (soybean, cottonseed, canola, sunflower, olive, peanut, corn), all of which contain only small amounts of Trans (1-2%). In commercial baking, spread is crucial since too much or too little spread affects the number of cookies per stock keeping unit (SKU). Several studies have shown that trans free fats have no effect on spread. (Tiffany, 2008; McNeil, 2005).
At least three very popular baked snack crackers (triscuits, wheat thins, chicken flavored) have been successfully reformulated to zero trans with liquid unhydrogenated soybean oil (Klemann, 2005). Trait modified soy, canola, and sunflower oils also should serve well since they are more oxidatively stable than commodity unhydrogenated soy containing 7-8% linolenic acid.
Pretzels, muffins, tortillas
Traditionally pretzel dough has been formulated with hydrogenated soybean oil. Reformulation to zero trans can be achieved by switching to unhydrogenated oil (Manirath, 2006). Normally pretzels contain about 2% fat needed for tenderness, mouth feel and structure/strength. Many home or packaged muffin mixes call for vegetable oil and thus are trans fat free. Flour tortillas often contain hydrogenated oils or animal fats because of improved machinability and reduced dough stickiness. However, trans fat labeling has stimulated interest in 100% liquid oils despite the possible sticking together when stacked in packages. Liquid oils not only provide a trans free solution but eliminates heating of the fat before usage. The reader is referred to a recent patent describing use of liquid oil in tortilla manufacture (Gerardus et al., 2009).