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A SURVEY OF THE NUMBER AND TYPES OF AEROBIC MESOPHILIC SPORES IN MILK BEFORE AND AFTER COMMERCIAL STERILIZATION
Author(s) -
FRANKLIN J. G.,
WILLIAMS D. J.,
CLEGG L. F. L.
Publication year - 1956
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1956.tb00043.x
Subject(s) - raw milk , food spoilage , sterilization (economics) , spore , mesophile , food science , biology , chemistry , microbiology and biotechnology , bacteria , genetics , monetary economics , economics , foreign exchange market , foreign exchange
SUMMARY: Milk, before and after commercial sterilization, supplied by ten different sterilizing depôts, was examined over a period of 18 months to determine the aerobic mesophilic spore content. The numbers present in raw bulk tanker milk exhibited a seasonal variation, the counts being higher in winter than in summer. This was not found in sterilized milk. Spore counts in raw milk ranged from 0—700/100 ml and in sterilized milk, with one exception, from 0—1·1/100 ml. During the last 12 months of the experiment the types of aerobic mesophilic spore forming organisms causing spoilage were isolated and identified, using a simplified method of identification. Eight different species were isolated from raw milk and seven from sterilized milk. The incidence of the different types in raw milk was: B. licheniformis , 62%; B. brevis , 15%; B. subtilis , 7%; others 9% and unidentified, 7%. In sterilized milk this was: B. subtilis , 44%; B. licheniformis , 26%; others, 17% and unidentified, 13%. There was no apparent seasonal variation in types.