220 MANUAL OF MILK PRODUCTS 



71. Method of obtaining samples. The samples to be examined 

 by the chemist shall have been examined previously by the bacteri- 

 ologist designated by the medical milk commission as to temperature, 

 odor, taste, and bacterial content. 



72. Fat standards. The fat standard for certified milk shall be 4 

 per cent, with a permissible range of variation of from 3.5 to 4.5 per cent. 



73. The fat standard for certified cream shall be not less than 18 

 per cent. 



74. If it is desired to sell higher fat-percentage milks or creams as 

 certified milks or creams, the range of variation for such milks shall 

 be 0.5 per cent on either side of the advertised percentage and the 

 range of variations for such creams shall be 2 per cent on either side 

 of the advertised percentage. 



75. The fat content of certified milks and creams shall be deter- 

 mined at least once each month. 



76. The methods recommended for this purpose are the Babcock, 

 the Leffmann-Beam, and the Gerber. 



77. Before condemning samples of milk which have fallen outside 

 the limits allowed, the chemist shall have determined, by control 

 ether extractions, that his apparatus and his technique are reliable. 



78. Protein standard. The protein standard for certified milk 

 shall be 3.50 per cent, with a permissible range of variation of from 

 3 to 4 per cent. 



79. The protein standard for certified cream shall correspond to the 

 protein standard for certified milk. 



80. The protein content shall be determined only when any special 

 consideration seems to the medical milk commission to make it de- 

 sirable. 



81. It shall be determined by the Kjeldahl method, using the Gun- 

 ning or some other reliable modification, and employing the factor 

 6.25 in reckoning the protein from the nitrogen. 



82. Coloring matter and preservatives. All certified milks and 

 creams shall be free from adulteration, and coloring matter and pre- 

 servatives shall not be added thereto. 



83. Tests for the detection of added coloring matter shall be applied 

 whenever the color of the milk or cream is such as to arouse suspicion. 



84. Tests for the detection of formaldehyde, borax, and boracic 

 acid shall be applied at least once each month. Occasionally appli- 

 cation of tests for the detection of salicylic acid, benzoic acid, and the 

 benzoates is also recommended. 



85. Detection of heated milk. Certified milk or cream shall not 

 be subjected to heat unless specially directed by the commission to 

 meet emergencies. 



86. Tests to determine whether such milks and creams have been 

 subjected to heat shall be applied at least once each month. 



