COMPOSITION OF NATUKAL FATS AND OILS 207 



toleic',*'''^'' caprylic, and lauric acids-'* have recently been isolated from 

 peanut oil. Small amounts of the higher saturated acids are present in soy- 

 bean oil.^'^ The composition of representative fats in this group are re- 

 ported in Table 15. 



(2) Glyceride Components of Natural Fats and Oils 



Although a considerable amount of information about the nature of a fat 

 can be gleaned from an examination of its fatty acid composition, the ar- 

 rangement of the fatty acids in the triglyceride molecule is of great im- 

 portance in establishing its physical properties. Thus, it is possible, by 

 the use of a catalyst, to cause a sample of an oil, such as cottonseed, to 

 change from a clear limpid liquid to one which is partially turbid, by an 

 alteration in the normal arrangement of the fatty acids to one of random 

 distribution. In fact, by means of directed interesterification, a product 

 can be obtained which, after thorough mixing, has a melting point well 

 above room temperature. All of these three fats have the same saponifica- 

 tion and iodine number and are composed of the same proportion of all the 

 fatty acids. The variation in melting points is ascribable entirely to dif- 

 ferences in the arrangement of the fatty acids in the triglyceride. 



a. Specific Glycerides Isolated from Natural Fats and Oils. The first 

 information available concerning the structure of fats was obtained by 

 the separation and identification of individual triglycerides. However, 

 such analyses prove to be extremely tedious and time-consuming, and the 

 results can in no way be considered quantitative. Moreover, only a few of 

 the individual triglycerides can be crystallized; in most cases it is impos- 

 sible to separate the components of complicated mixtures. 



(a) Simple Triglycerides Isolated from Natural Fats and Oils. The simple 

 triglycerides are present in limited quantities in the fats and, in most cases, 

 can be isolated in pure form only after many fractionations and crystalliza- 

 tions. Duffy, ^'^ in 1853, was able to isolate 8 g. of tristearin from 2 kg. of 

 mutton tallow, and this required 32 recrystallizations from ether at 16°C. 

 The same mvestigator succeeded in preparing 2 g. of the same triglyceride 

 from beef tallow. Bomer et aL^*'''"* separated 3% of pure tristearin from 

 mutton tallow by systematic ciystallizations of natural fats. In some 



"3 T. P. Hilditch, Rec. Imv. chim., 57, 501-508 (1938). T. P. Hilditch and H. Jasper- 

 son, /. Soc. Chem. Ind., 57, 8-i-87T (1938). 



"< H. L. Wvkoff, J. M. Kaplan, and A. L. Herman, /. Biol. Chem., 153, 227-235 

 (1944). 



2« E. G. Dollear, P. Kiauczunas, and K. S. Maikley, Oil & Snap, 15, 263-2G4 (1938); 

 17, 120-121 (1940). 



•-2« P. Duffy, /. Chem. Soc, 5, 197-210 (1853). 



-'^ A. Bonier, A. Schenim, and G. Heinisoth, Z. Unttisuch. Xuhr. Genussin., 14, 90-117 

 (1907). 



'-'"* A. Biimer and G. Ileinisoth, Z. Untersuch. Nahr. Geaussin., 17, 353-396 (1909). 



