Prediction of the shelf‐life of pasteurized milk at different storage temperatures

Initial psychrotroph counts determined by a Most Probable Number technique were correlated with shelf‐lives of pasteurized milk determined at a number of storage temperatures. The initial psychrotroph count was also correlated with a bacterial count carried out on milk agar containing crystal violet penicillin and nisin after previous incubation of the milk at 15°C for 25 h. Pre‐incubation counts carried out at a variety of temperatures and on a variety of media were examined for their relation to shelf‐life. Shelf‐lives at four pre‐set temperatures (2, 6, 10 and 14°C) could best be predicted by pre‐incubation of pasteurized milk at 15°C before inoculation on milk agar. An equation which allows prediction of shelf‐life of pasteurized milk at any storage temperature is described.