. Milk. Milk. 518 MILK customers believed the milk had been skimmed. It is natural, therefore, that the temperature for flash pasteurization was gradually reduced, until at present the average temperature prac- tised in this country is ° C. (160° F.). This temperature cannot be depended upon to destroy all pathogenic bacteria, al- though it results in a material reduction of bacteria. There are, then, two objections to flash pasteurization at 160° F.: 1, apparent reduction of the quantity of cream, and 2, uncertainty as to the destruction of pathogenic bacteria. ttroma strr i*. Fig. 206.—^
. Milk. Milk. 518 MILK customers believed the milk had been skimmed. It is natural, therefore, that the temperature for flash pasteurization was gradually reduced, until at present the average temperature prac- tised in this country is ° C. (160° F.). This temperature cannot be depended upon to destroy all pathogenic bacteria, al- though it results in a material reduction of bacteria. There are, then, two objections to flash pasteurization at 160° F.: 1, apparent reduction of the quantity of cream, and 2, uncertainty as to the destruction of pathogenic bacteria. ttroma strr i*. Fig. 206.—^A regenerative pasteurizer for use with holding tank. (S. H. Ayera in Circular 184, Bureau of Animal Industry, U. S. Dept. of Agriculture.) 2. The holding process overcomes these difficulties in large measure. The holding or held process, as originally designed, means that the milk is heated to 60° C. (140° F.), held at this temperature for twenty minutes, and finally cooled. The cream line is not appreciably affected, and the temperature and period of exposure are sufficient to destroy pathogenic bacteria. In laboratory experiments the holding process has proved to be efficient when the milk is heated to 140° F. for twenty minutes,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Heinemann, Paul Gustav. Philadelphia and London, W. B. Saunders Company
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