190 



On the other hand, the iodine number is lowest in the fat soluble in 

 alcohol and highest in the fat of the soft portion. 



The figures in the above table show the influence of the constants on 

 the melting point of butter fat. The portion of fat insoluble in alcohol 

 and the original fat from which the above portion was taken show a de- 

 cidedly higher iodine number than, the portion soluble in alcohol. If the 

 melting point depended solely on the iodine number, the melting point of 

 the fat insoluble in alcohol and of the original butter fat would be dis- 

 tinctly lower than the melting point of the portion soluble in alcohol. 

 Table VII shows that this is not the case. The melting point of the por- 

 tion insoluble in alcohol and of the original butter fat is a great deal 

 higher (19.1° C. and 16.6° C, respectively, higher) than the melting point of 

 the fat soluble in alcohol. The only factor to which this fact can be attrib- 

 uted is the high Reichert-Meissl No. in the case of the fat soluble in 

 alcohol, as compared with the low Reichert-Meissl No. of the fat insoluble 

 in alcohol and of the original butter fat. These results make it perfectly 

 clear that the softness or hardness (melting point) of butter fat is de- 

 pendent to a great degree on the per cent of soluble fatty acids present. 



This table further shows, as stated in the previous chapters, that 

 butter fat is a mixture of triglycerides of different fatty acids. The soft 

 portion is the result of mechanical separation at different temperatures. 

 It, therefore, contains more glycerides combined with acids of low melting 

 points including oleic and soluble acids. Furthermore, the fat soluble in 

 alcohol represents glycerides of acids soluble in alcohol. Since it is known 

 that some of the glycerides of the soluble acids are soluble in alcohol, 

 we can assume that some of the molecules in butter fat are made up of the 

 glycerides containing a larger proportion of the soluble acids than others. 



CONDITIONS AFFECTING THE COMPOSITION OF BETTER FAT. 



The composition of butter fat varies with the season of the year. A 

 series of analyses of butter fat of butter made during each of the twelve 

 months of the year, yielded the results summarized in Table VIII. 



The results in Table VIII show that the Reichert-Meissl number was 

 lowest in October, increasing steadily until it reached its maximum in 

 March. After March it dropped abruptly, holding about its own till July, 

 then taking a second drop and declining slightly toward October. 



