534 COMPOSITION AND PROPERTIES OF BUTTER 



Table 73. 



Tri-butyrin 60 to 70 C. or 76 to 94 F. 



Olein 5 C. or 41 F. 



Myristin 54 C. or 129 F. 



Palmitin 61 C. or 142 F. 



Stearin 65.5 C. or 150 F. 



Both the butyrin and the olein have melting points much 

 lower than the other insoluble fats. A material increase in the 

 proportion of butyrin or olein, or both, therefore suggests a 

 lowering of the melting point of the mixed fat and vice versa. 

 This fact has been amply demonstrated by Eckles 1 and by Hun- 

 ziker 2 . Exceptions to these facts are not infrequent, however, 

 and they must be largely attributed to the fact that the volatile 

 acids in such cases were made up of unusually high proportions 

 of the less common constituents, such as caprylic, capric and 

 lauric acids, whose melting points are 16.5, 31.3 and 43.6 de- 

 grees C., respectively, as suggested by Eckles, or that the rela- 

 tive proportion of the glycerides of the individual soluble and 

 insoluble acids exclusive of oleic, must have exerted a dominant 

 influence, as suggested by Hunziker. Again, Lewkowitsch 3 

 points out that the melting point of a mixture of fats cannot be 

 predicted from the melting points of the fats themselves ; and 

 Twitchell 4 shows the interesting fact that a mixture of palmitic 

 and stearic acids lowers the solidifying points of each other to 

 a greater extent than a mixture of either of these two acids with 

 oleic acid. 



Barring these exceptions, and for all practical purposes, the 

 fact remains that a high percentage of butyrin, or of olein, or 

 of both, causes the mixed butterfat to have a relatively low 

 melting point, while a low percentage of butyrin, or of olein, 

 or of both, causes the mixed butterfat to have a relatively high 

 melting point. Therefore, in early summer, when, because of 

 the freshening of the majority of the cows, the per cent of bu- 

 tyrin is relatively high, and because of the cows gorging them- 



1 Eckles and Palmer Influence of Plane of Nutrition of the Cow Upon the 

 Composition and Properties of Milk and Butterfat. Missouri Research Bulle- 

 tin 24. 1916. 



2 Hunziker, Mills and Spitzer Moisture Control of Butter, Factors not 

 under Control of the Buttermaker. Purdue Bulletin 159, 1912. 



3 Lewkowitsch Chemical Technology and Analysis of Oils, Fat and 

 Waxes, Vol. I, 1909. 



* Twitchell Journal Ind. Eng. Chem., Vol. VI, p. 564, 1914; also Analyst, 

 Vol. XXXIX, p. 448, 1914. 



