'BITTY' CREAM: THE OCCURRENCE AND SIGNIFICANCE OF BACILLUS CEREUS SPORES IN RAW MILK SUPPLIES

SUMMARY: Methods for determining the Bacillus cereus content of milks and of rinses of dairy equipment are described and their limitations discussed. Milk samples from various sources were examined throughout the year for 'bittiness' as well as for B. cereus. The organism was not detected in all samples showing bittiness. There was a marked seasonal variation in the B. cereus index of raw milk supplies; maximum numbers were obtained from July to September and minimum numbers in April and May. Rinses of farm dairy equipment yielded few B. cereus spores but milk cans not uncommonly contained large numbers, especially in the summer months, when 10·5% of cans showed more than 5 × 10³/can. Preliminary observations on other sources of B. cereus are described and some of the problems of the control of this organism in raw milk supplies are discussed.