A Nutritional Concept of the Germicidal Property of Raw Milk

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Abstract
The growing of micro-organisms with simple, intermediate, and complex media requirements, in raw whey from cows milk, suggests that they may be classified as sterilized, inhibited, or uninhibited as a result of such exposure. Reducing agents such as glutathione, mercaptoacetic acid, stannous chloride, sulfanilamide, sodium sulfite, thiamine, ascorbic acid, and hydroxyl-amine eliminated the lethal effect of unheated whey for Streptococcus pyogenes but did not allow growth of this microorganism in unheated whey. Addition of meat infusion and yeast extract broths allowed the growth of S. pyogenes in unheated whey as did albumin preparations heated sufficiently to demonstrate the presence of free sulfhydryl groups. The minimum heat treatment required to permit the growth of S. pyogenes in whey is also the minimum required for the detection of free sulfhydryl groups in milk or whey. The decrease of free sulfhydryl groups in whey, upon prolonged heating, coincides with the decreased growth of S. pyogenes in whey treated in a similar manner. Experiments with p-chloromercuribenzoate and cysteine suggest that a deficiency of free sulfhydryl groups and/or denatured albumin in raw milk and whey is a major cause of the lethal effect of this medium for S. pyogenes.