Microbiological aspects of goat's milk. A Public Health Laboratory Service survey

Abstract

SUMMARY: In a 12-month survey (June 1982–May 1983) 41 laboratories examined 2493 samples of goat's milk for colony counts and the presence of pathogens. The statutory tests for cow's milk were also applied.Surface counts of < 10⁵ organisms per ml of raw milk were given by 79% of samples at 37 °C and by 76% at 22 °C. There were < 100 coliforms per ml in 71% of samples, < 10 Escherichia coli per ml in 91%. Staphylococcus aureus was not detected in countable numbers in 96% of samples. Only one isolation of campylobacter was made and two of Yersinia enterocolitica. Salmonella was not detected in 2462 samples. The methylene blue test was carried out on 2368 samples and 86·7% were deemed satisfactory. No sample was Brucella ring-test-positive.Experiments on the survival and growth of six food poisoning organisms in stored goat's milk showed that Bacillus cereus, Staph. aureus, Salmonella typhimurium and Y. enterocolitica survived quite well and multiplied at the higher storage temperature of 30 °C. Clostridium perfringens only increased 10- to 100-fold while Campylobacter jejuni did not grow.The results of the survey indicate that any problems with goat's milk relate to poor hygiene during production rather than transmission of organisms from the goat herself.