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Some insight into the mechanism of inhibition of psychrotrophic bacterial growth in raw milk by lactic acid bacteria
Author(s) -
Griffiths M W,
Banks J M,
Mcintyre L,
Limond A
Publication year - 1991
Publication title -
international journal of dairy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.061
H-Index - 53
eISSN - 1471-0307
pISSN - 1364-727X
DOI - 10.1111/j.1471-0307.1991.tb00625.x
Subject(s) - lactic acid , bacteria , psychrotrophic bacteria , raw milk , food science , chemistry , bacillus circulans , population , bacterial growth , microbiology and biotechnology , biology , genetics , demography , sociology
Addition of lactic acid bacteria to refrigerated raw milk inhibited growth of Gram‐negative psychrotrophic bacteria. In order to obtain complete inhibition, population levels of lactic acid bacteria approaching 1× 10 8 cfu/ml were required. At this inoculum level a substantial pH change was observed in the milk during storage. The degree of inhibition was related to the final pH of the milk. Inhibition of the psychrotrophs was brought about by adjustment of pH with L(+) lactic acid but not by HCI. Inhibition by the lactic acid bacteria was observed in heat‐treated milks seeded with a small volume of raw milk, but no inhibition of Gram‐negative psychrotrophic growth was observed when cell‐free preparations of lactic acid bacteria were used. A cell‐free ultrafiltrate of one lactic acid culture did inhibit a strain of Bacillus circulans.