ADULTERATION OF CHEESE. 



383 



water is removed at the ordinary temperature, and, whilst the 

 method is fairly quick, there is no material loss of organic matter, 

 such as occurs with long-contiaued drying at 100° C. Complete 

 drying in vacuo is too tedious and often impracticable. 



The following examples show the accuracy of this process : — 



TABLE cm. 



Adulteration of Cheese.— The only forms of adulteration 

 of any importance consist in the substitution of skim milk cheese 

 for whole milk cheese, or milk cheese for cream cheese, and the 

 addition of fat not derived from milk to skim milk before making 

 it into cheese. 



The former adulteration is detected by the estimation of 

 fat and total nitrogen. In a whole milk cheese the ratio 



r^-. — r- ^-_-o varies from 1 to 1 '5 ; in a skim milk cheese 



total nitrogen X 6 'So 



it is usually less than 1 . 



Another method consists in calculation of the composition of 

 the original milk (or cream) ; the author has found that the 

 following calculation gives a ver}- fair approximation to the 

 composition of the milk or cream from which the cheese was 

 prepared. 



Multiply the percentage of proteins by 35 '4, add the percentage 

 of fat, and divide 100 times the percentage of fat by the figure 

 thus obtained ; to the resulting figure add 0-25, and the sum 

 will be a close approximation to the percentage of fat in the 

 nulk or cream used for the preparation of the cheese. Owing 

 to the natural variations of the ratio of fat to proteins in cheese, 

 and of the loss of fat in the whey, no cheese should be certified 

 by this method to be made from skimmed milk unless the calcu- 

 lated fat is less than 2 "75 per cent. Similarly it is not advisable 

 to condemn a cream cheese unless the calculated percentage of 

 fat falls below 10 per cent. 



The addition of foreign fat is detected by an examination of 



