I08 MILK PEODTJCTS 



sulfuric acid, and, after boiling, the excess of acid 

 is neutralized with standard sodium hydroxid, 

 using rosolic acid as indicator. 



Amino-compounds. — These are determined by 

 macerating the powdered cheese in water for 

 fifteen hours at the ordinary temperature. After 

 adding a little dilute sulfuric acid (1:4), the pro- 

 teins and peptones are precipitated by phospho- 

 tungstic acid. The precipitate is filtered oflE and 

 washed with water containing a little sulfuric acid. 

 The filtrate is made up to a definite bulk, and the 

 nitrogen is determined in an aliquot portion of 

 the Uquid by the Kjeldahl-Gunning process, 

 allowance being made for the nitrogen existing as 

 ammonium. 



Peptones and Albumoses. — These are deter- 

 mined jointly by boiling the powdered cheese 

 (mixed with sand as before) with water and 

 filtering from the undissolved casein and albumin. 

 In an aliquot portion of the filtrate the peptones 

 and albumoses are precipitated by adding dilute 

 sulfuric acid and phosphotungstic addL After 

 washing with acidulated water the nitrogen mf 

 the precipitate is determined by the Kjeldahl- 

 Gunning process. 



The total nitrogen of the cheese is also deter- 

 mined, and after allowng for the nitrogen ex- 

 isting as other forms, the remainder is calculated 

 to casein. 



