The Keeping Quality of Pasteurized Milk in the New York Metropolitan Area during Cool Weather as Determined by Bacterial Counts, Presence of Coliform Bacteria, and Flavor Scores

Abstract

Freshly pasteurized milk in the New York Metropolitan area gave a standard plate count of about 12,000 per ml. There were 3 samples from 54 quarts of milk that were positive on 2 out of 3 brilliant green fermentation tubes or 2 out of 2 desoxycholate agar plates. The flavor of the milk was excellent. When stored at 35-40[degree]F the bacterial counts were lower at the end of 4 days when the final samples were taken than in the fresh milk. The coliform tests were uniform for the 4 days. The flavor was still good and free of objectionable off-flavors after 7 days. At 45-50[degree]F the first noticeable increase in count was secured in the 3-day-old milk and the count averaged 180,000 in 4 days. About half of the milks became positive for coliform bacteria in 4 days. The flavor remained good for 7 days. At 55-60[degree]F the standard plate count had increased to 134,000 at the end of the 2d day and to millions thereafter. In 4 days the total samples positive for coliform bacteria was 41 out of 54 bottles of milk. The flavor was good for 3 days. Milk in homes should not be stored above 50[degree]F to best safeguard the healthfulness of milk.