The Microflora of Hand Washed Milk Bottles

Abstract

The examination of a series of 713 milk bottles cleansed by hand washing at producer-retailer farm dairies showed that though nearly 60% attained satisfactory bacteriological standards, about 30% gave high colony counts (> 600/bottle), while coli-esrogenes organisms were found i n 17% and milk spoilage organisms in 26% of them. The microflora of efficiently cleansed bottles, with colony counts of <200/bottle. waa dominated by micrococci and aerobic sporeforming rods. Only 3.7% of the 269 cultures from these bottles gave acid reactions i n litmus milk in 72 h at 22". Inefficiently cleansed bottles, with colony counts of >600/bottle, had quite a different type of microflora which was usually dominated by Gram negative rods (achrornobecteria, noduorescent pseudomonads and flavobacteria). A much higher proportion (19%) of the 393 cultures from these bottles gave acid reactions in litmus milk. P PI b E P, U 8 3. * After incubating at 30" for 72 h. t After hcUb8thg at 22" for 72h.

Incidence and Significance of Thermoduric Bacteria in Farm Milk Supplies: A Reappraisal and Review

“…Hand washed milk bottles from producer-retailers rarely contain enough thermoduric bacteria to make a significant contribution to the heat resistant flora of milk placed in them. Griffiths, Morgan, Pritchard & Thomas (1952) and Thomas, King & Davies (1966) found that although about 50% of the bacteria isolated from farm bottles were therinoduric micrococci and sporeforming bacilli ; relatively few bottles (18%) contained more than one thermoduric organism per ml capacity.…”