II 



BUTTER 



'57 



C. DETECTION OF THE ADULTERATION IN BUTTER. 

 1. ADMIXTURE OF FOREIGN FATS. 



It is only to be expected that such a valuable and costly food 

 as butter should be particularly liable to adulteration. The 

 most usual way of adulterating butter, and at the same time 

 often the most difficult to detect, consists in mixing with the 

 butter a portion of cheaper and less valuable fat, either animal 

 or vegetable. The main difference between butter fat and 

 other fats lies in the fact that the former, whilst composed of 

 glycerides of non-volatile fatty acids, viz., palmitin, stearin, and 

 olein, as are other fats, contains also a number of glycerides of 

 volatile, partly soluble, fatty acids of low molecular weight, viz., 

 butyrin, capronin, caprylin, caprin. A full list of the fatty 

 acids normally found in butter fat is the following : 



Butyric acid 



Caproic 



Caprylic 



Capric 



Laurie 



Myristic 



Palmitic 



Stearic 



Arachidic 



Oleic 



C 4 H 8 2 

 C 6 H 12 2 



(volatile) 



L 0" 2 

 C, 2 H 24 0<, (non 



c 14 H 28 o; 



C ]6 H 32 2 



^18 H 362 



volatile) 



Laurie, myristic, and arachidic acids are only present in very 

 small quantities. 1 The glycerides of the first four of the above 

 acids, which are volatile and characteristic of butter fat, usually 

 make 7-9 per cent, of the total weight. The presence of these 

 four glycerides in butter fat, particularly the butyrin, is, more- 

 over, the only peculiarity which distinguishes it, as far as 

 composition goes, from other fats. Therefore the admixture of 

 foreign fat with the butter causes the non- volatile fatty acids 

 to increase, whilst the quantity of volatile fatty acid diminishes. 

 As, however, the proportion of volatile fatty acids in butter is 

 by no means constant, it is often extremely difficult, judging 

 by the amount of volatile fatty acid, to decide whether or not 

 falsification has taken place, particularly when only small 

 quantities of foreign fat have been added. By far the majority 

 of the methods which can be used to detect admixture of 



1 According to Siegfeld (Zeitschr. filr Untersuch. d. Nahr- und Genussmittel, 

 1907, Vol. I, p. 513), butter fat contains less stearic and more myristic acid 

 than was previously supposed. 



