THE JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION

EFFICIENT PASTEURIZATION AND THE BACTERIA WHICH MAY SURVIVE IT  It has been demonstrated both experimentally and commercially that practically no pathogenic bacteria survive a temperature of from 60 to 65 C. (140 to 149 F.) continued for thirty minutes or longer. Yet the most efficient pasteurization will not destroy all the organisms in milk, and the growth of the survivors markedly affects the quality of the milk. Ayres and Johnson¹ have recently published the results of an extended study of the effects on milk of the organisms which survive pasteurization. Data were collected from 219 pasteurizing plants in cities of over 25,000 as to the methods and temperatures employed. It was found that seventy-five plants were using the holding process with an average temperature of 62.8 C. (145 F.), and 144 plants were using the "flash" process, heating the milk to an average temperature of 71 C. (159.8 F.)