24 BULLETIN 24-0, U. S. DEPARTMENT OF AGRICULTURE. 



A study of the results in Table 8 shows that the cream-line forma- 

 tion is a variable factor. Sometimes it was reduced by pasteuriza- 

 tion even when the milk was cooled to low temperatures within 15 

 seconds, and at other times there was no difference. In some ex- 

 periments the cream line was slightly less on milk cooled slowly and 

 again it was slightly higher. Throughout the experiments on pas- 

 teurized milk bottled hot in ordinary milk bottles a good clear cream 

 line was obtained. When milk stood at temperatures above 80° F. 

 for several hours without agitation some of the melted butter fat rose 

 to the top of the bottle and on cooling formed a small lump of 

 butter. This was not observed, however, when the cooling process 

 was begun immediately after bottling, even though the cooling was 

 gradual. 



As to the effect on the flavor of the milk, it may be said that there 

 was no more effect than that produced by milk pasteurized and 

 cooled rapidly, except in instances where the milk was held above 

 100° F. for several hours, as was the case in some of the experiments, 

 in which a slightly more pronounced cooked taste was noticeable in 

 the milk. 



In this connection attention is called to the fact that these results 

 hold only for milk pasteurized at 145° F. and can not be applied 

 where higher temperatures might be used, as it is possible that with 

 higher temperatures different results might be obtained. . 



BOTTLES TO BE USED IN THE PROCESS OF BOTTLING HOT 

 PASTEURIZED MILK. 



It is obvious that a quart bottle filled with milk at 145° F. will not 

 contain a full quart when the milk has cooled to 50° F., owing to the 

 contraction during cooling. Several experiments which were made 

 to determine the loss in volume during cooling showed a shrinkage 

 in a quart bottle which averaged about 18.40 cubic centimeters. As- 

 suming a quart of milk to be 946.35 cubic centimeters, that volume at 

 145° F. would therefore contract to about 9-27.95 cubic centimeters 

 when cooled to 50° F. If a quart bottle is filled with milk at 145° F., 

 it will be 18.40 cubic centimeters, or 0.62 of an ounce, short of 1 quart 

 when cooled to 50° F. To overcome this shortage bottles of a slightly 

 larger capacity should be used when filled with milk at 145° F. A 

 bottle should be of sufficient size to hold 1 quart of milk measured 

 ;:( 50° F. which has been heated to 115° F. 



PROCESS OF BOTTLING HOT PASTEURIZED MILK UNDER COMMER- 

 CIAL CONDITIONS. 



Having discussed the various steps in the process of bottling hot 

 pasteurized milk, the possible application of this process of commer- 

 cial conditions may be outlined. 



