Pioneers of Fat Polymorphism
The fact that trigylcerides may exhibit more than one melting point was reported by Duffy in 1852. However the nature and understanding of polymorphism required nearly 100 years and the research efforts of Thomas Malkin and Edwin Lutton.
Thomas Malkin was born in Warrington England and had worked in the laboratories of Joseph Crosfield and Son (a soap manufacturer) where he became interested in lipids. Malkin received a B.Sc. from the Manchester College of Technology in 1923 and a Ph.D. in 1926. Malkin began his career at the University of Bristol where he remained for the rest of his life. He began as a lecturer, senior lecturer, and eventually reader in 1945. In 1934 the University of London awarded Malkin the D.Sc. degree. At Bristol there was great interest in long chain compounds and Malkin joined Professor Francis who was using x-ray diffraction for the study of long chain fatty acids. In 1931 Malkin reported an explanation of the alteration of long chain compounds in the solid state depending on odd or even chain lengths. By 1952 the work had been extended to mono, di, and simple or mixed trigylcerides. World War Two interrupted his research long enough to assist in the war effort to produce munitions and explosives for the Ordnance Department. In his later years Malkin turned his attention to phospholipids and published extensively in this area of research. In 1934 Clarkson and Malkin published a controversial paper entitled “Alteration in long chain compounds Part II. An x ray and thermal investigation of trigylcerides” (J. Chem. Soc. p. 666, 1934). These authors reported that tristearin exhibits four polymorphs: vitreous (lowest MP 55C), an intermediate alpha (MP 64C), beta prime (MP 70C) and beta (highest MP 73C). Others including A.E. Bailey, Lutton, and Filer re-examined Malkin’s work by the use of x-ray diffraction and melting point data. All agreed that tristearin exhibits just 3 melting points alpha, beta prime and beta. Thus, the vitreous form reported by Malkin is the alpha form, and the 2 intermediates are Beta prime, with beta the highest melting polymorph. Despite much criticism, Malkin defended his results but ultimately Lutton prevailed as will be discussed later.
Edwin Lutton was born in 1911 in Pennsylvania. He graduated with an A.B. from Swathmore College in 1932. Three years later he received a Ph.D. in physical chemistry from Yale University. He began his career in the fats and oils group at Proctor and Gamble in Cinncinati in 1935 and spent his entire career there before his retirement in 1971. Lutton was the first industrial scientist to receive the AOCS Award in Lipid Chemistry (1971). At the age of 86 he was awarded the North Central AOCS Bailey Medal (1997) in recognition of his outstanding research on fats oils, and lipids. Lutton’s interest in polymorphism began shortly after he joined Proctor and Gamble. His first publication appeared in Chemical Reviews, “The polymorphic forms or phases of triglyceride fats” (Ferguson and Lutton, pp. 355-384, 1941). Shortly thereafter Lutton began to look at the polymorphic behavior of tristearin and the results were published in the Journal of the American Chemical Society (vol.67 pp 524-527, 1945). He pointed out that his findings confirmed Malkins results since the melting points and x-ray diffraction patterns were nearly identical. However the alpha form reported by Malkin to be the intermediate form was in reality the beta prime form. Thus, tristearin exhibits three polymorphic forms (alpha MP 54.5C, beta prime MP 64C, beta MP 73.1C) not four reported by Malkin. The controversy continued but Malkin firmly defended his position despite criticism from others including A.E. Bailey and Filer. Lutton set out to prove his results once and for all. In 1954 he published a paper entitled “Pictorial proof of alpha (55C) and beta prime (64C) MP levels for tristearin” (JACS, 77 pp. 2646-47, 1955). Lutton concluded that differences in experimental techniques was most likely for the confusion. Malkin used one procedure for treating x-ray samples and another for melting point observations. Lutton used the same procedure for both analyses. His experimental approach involved preparation of the various polymorphs and simultaneous determination of their melting points and x-ray diffraction patterns. (On advice from the editor the photographic plates were not published but were deposited as document 4460, and can be obtained from the Library of Congress, Chief Photoduplication Service.)
In 1955 Lutton published a classic paper on the phase behavior of triolein, tristearin and oleodistearin by use of melting point data, x-ray diffraction, and dilatometry. (Lutton J. Am. Oil Chem. Soc. 32 pp. 49-53). His findings confirmed that the Hildebrand solubility relation is valid for binary fat systems until the higher melting component begins to appear. It should be pointed out that his results were based on methods not available to those working in the field today (i.e. DSC, NMR, Mettler drop points). Furthermore Lutton gave equations for the calculation of solubility based on Hildebrand’s law. Anyone entering the field today will find this paper most useful and interesting.
Lutton published extensively in the area of fat polymorphism and crystallization. Often synthesis and purification of model compound were required before further study. Space does not allow not allow a detailed discussion. A Google scholar search/Google patent will list his many publications all of which are in top journals.
Lutton’s basic research on polymorphism and fat crystallization was instrumental in the development of plastic shortenings from soybean oil. Proctor and Gamble’s CRISCO shortening (cottonseed oil based) had been on the market for about 25 years when Lever Brothers marketed (1936) SPRY shortening in hopes of competing with CRISCO. Spry was advertised as an all hydrogenated vegetable oil (cottonseed) shortening and eventually achieved 75% of CRISCO’s market share. Spry was in the retail market up until the 1970’s when it was discontinued. Cottonseed oil based shortenings were easy to manufacture, performed well but plasticity defects such as stiffening at elevated temperature for extended periods were sometimes observed. On the other hand, when soybean oil was used as a substitute for cottonseed oil difficulties were encountered in matching the physical properties of all cottonseed shortenings. For example, blending a hydrogenated soybean base with cottonseed hard stock lead to stiff consistency when stored at 90F. Lutton attributed this phenomena to a beta prime crystal habit from the cottonseed oil. P and G researchers began development of fluid shortenings in the late 1940’s and were granted a US Patent in 1950 (Holman and Quimby, US 2 521 219). Fluid shortenings are opaque suspensions of hard fat in a partially hydrogenated base and, as such, are pourable. Apparently the new shortening (SWIRL) was test marketed and claims included the ease of handling and measuring coupled with excellent creaming properties with sugar. The new shortening was emulsified and designed for the housewife for baking of cakes. Nonetheless, the test marketing was not successful and the product was never commercialized. However, fluid shortenings were very successful in the food industry especially when emulsifier and or surfactants were included.
Lutton’s vast knowledge of polymorphism and fat crystallization lead to the development of improved plastic shortenings. By the use of blending techniques common vegetable oils containing high levels (90%) of C18 fatty acids and hardstocks can be crystallized in the beta crystal form and with special tempering yields shortening with cake volumes equal to or better than a beta prime commercially prepared shortening from hydrogenated vegetable oil (US 2 801 177, 1957). These findings allowed the use of soybean oil (a beta tending fat) in shortening formulations and overcame some of the difficulties with cottonseed oil based products and kept CRISCO at the top of the retail shortening market. Some have claimed that the improved CRISCO spelled the end of Lever Brothers SPRY.
Notes and Further reading:
Thomas Malkin was a co-editor of Progress in the chemistry of fats and other lipids, Pergamon Press He authored a chapter, “The polymorphism of gylcerides” (vol. 2 pp. 1-50 21, 1954). Malkin passed away in 1961. Volume 3, 1963 contains a bio and a list of his publications. pp Ix –xiii.
E.S. Lutton (1911-2005) was a contemporary of A.E. Bailey who authored the book “Melting and Solidification of Fats” Interscience Publishers, New York, 1950. This work is still an invaluable resource for the lipid chemist. Bailey acknowledged Lutton: “who most generously went over all the chapters and not only eliminated numerous errors in the original draft but contributed many valuable original suggestions.” Upon publication, Bailey sent Lutton a copy with the inscription, “Here’s a copy of the book we wrote. Hope you like it, Ed Bailey.”
In This Section
- Patrick Duffy and Polymorphism
- Alton E. Bailey (1907-1953)
- Stephen S. Chang (1918-1996)
- Michel Eugène Chevreul (1786-1889)
- Herbert Dutton (1914-2006)
- Eddy W. Eckey, Father of directed Interesterification (1902-1989)
- Edwin (Ed) Frankel (1928-2019)
- Thomas Percy Hilditch (1886-1965)
- Ralph Theodore Holman (1918 - 2012)
- George S. Jamieson (1879–1959)
- Percy Lavon Julian (1899-1975)
- Hans Paul Kaufmann (1889-1971)
- David Kritchevsky (1920 to 2006)
- Hippolyte Mège (1817-1880)
- Virgil C. Mehlenbacher (1901-1992)
- Wilhelm Normann (1870-1939)
- Hermann Pardun (1908-2009)
- Paul Karl Stumpf (1919-2007)
- Ernst Twitchell (1863-1929)
- David Wesson (1861-1934)
- Harvey W. Wiley (1844-1930)
- Hermann Bollmann (1880-1934), Bruno Rewald (1882-1947), Heinrich Buer (1875-1962), Stroud Jordan (1885-1947), Percy Julian (1899-1975), Joseph Eichberg (1906-1997)
- John C. Cowan (1911-1991)
- Artemy A. Horvath (1886-1979)
- T.M. Malkin (1879-1961) and E.S. Lutton (1911-2005)
- Wilhelm Heintz (1817-1880)
- Cyril D. Evans (1909-1979)
- Dr. Timothy Lee Mounts (1937-1997)
- Earl G. Hammond (1926-2017)
- Arthur Richard Baldwin (1918-2011)
- Thomas H.Applewhite (1924-2012)
- Arthur Richard Baldwin (1918-2011)