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The Nursling

By Pierre Budin, Professor of Obstetrics, University of Paris; Director of the Clinique Tarnier; Member of the Academy of Medicine, Paris, France. Authorized translation by William J. Maloney, M.B., Ch. B., 1907.

Appendix V

Researches on the Temperature of Milk During the Process of Sterilisation

M. Chavane demonstrated in my laboratory at the Charité that milk immersed in boiling water for forty-five minutes attained the temperature of the water -- 100° C. His results, however, have been disputed. Marfan [1] writes:

"What is the actual temperature of the milk contained in the small bottles when surrounded by the boiling water of the steriliser for forty-five minutes? Some say that it does not exceed 80° C.; Chavane alleges that it reaches 100° C.; so I re-investigated the question. During various phases of the sterilisation I placed a thermometer, graduated to 200° C., in the small bottles. After a quarter of an hour the temperature of the milk is between 90° and 92° C.; after half-an-hour, between 95° and 96° C. As I never found it surpass the last figure, the casein ferment is probably not destroyed by this process. The efficiency of the sterilisation varies with the duration of the heat: according to Freer, after fifteen minutes heating several hundreds of colonies develop within twenty-four hours; after thirty minutes, several dozens, and after forty-five minutes sterile plates are often obtained. Rodet corroborates these results."

I asked M. Nicloux to repeat M. Chavane's experiment. He did so, avoiding all possible sources of error with the greatest care. His results show that the milk quite readily attains a temperature in the neighborhood of 100° C., viz. 99.9° C. One cannot conceive how it could be otherwise. He used a specially constructed thermometer of great precision, graduated in fifths of a degree to 200° C. Variations of 1/16 of a degree could be readily appreciated by it. The experiments were carried out with the same apparatus as is daily used to sterilise milk in the Clinique. M. Nicloux says:

"I placed one thermometer in the water of the steriliser, and another in one of the small bottles containing the milk which was being sterilised. As I could not then put on the lid, I used a folded towel to prevent the steam escaping too freely. Temperature readings were taken every five minutes, as is seen in the first curve (the abscissa represents time; the ordinate, degrees Centigrade). The dotted line marks the beginning of boiling; the temperature at boiling-point was 96° C. in the steriliser, and 77° C. in the small bottles. After this point was reached, readings were taken every two and a half minutes. Ten minutes later the temperature was found to be 100° C. in the steriliser and 99° C. in the small bottles. On multiplying the ordinate by 20 (Curve 2) one finds, that while the temperature of the water remains constant at 100° C., that of the milk in the small bottles rises till it attains 99.9° C., but no further."

[1] Marfan, Traite de l'allaitement et de l'alimentation des enfants, Paris, 1899.

Fig. 124. Curve of the temperature of the water contained in the steriliser, and of the bottles immersed in it.

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