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The use of the bacteriocin, nisin, as a preservative in ricotta‐type cheeses to control the food‐borne pathogen Listeria monocytogenes
Author(s) -
Davies E. A.,
Bevis H. E.,
DelvesBroughton J.
Publication year - 1997
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.1997.00145.x
Subject(s) - nisin , listeria monocytogenes , food science , bacteriocin , preservative , incubation , microbiology and biotechnology , food preservation , pasteurization , pathogen , biology , incubation period , biopreservation , cold storage , food microbiology , listeria , bacteria , chemistry , antimicrobial , biochemistry , horticulture , genetics
The efficacy of nisin to control the food‐borne pathogen Listeria monocytogenes in ricotta‐type cheeses over long storage (70 d) at 6–8°C was determined. Cheeses were prepared from unpasteurized milk by direct acidification with acetic acid (final pH 5·9) and/or calcium chloride addition during heat treatment. Nisin was added in the commercial form of Nisaplin ® pre‐production to the milk. Each batch of cheese was inoculated with 10 2 –10 3 cfu g −1 of a five‐strain cocktail of L. monocytogenes before storage. Shelf‐life analysis demonstrated that incorporation of nisin at a level of 2·5 mg l −1 could effectively inhibit the growth of L. monocytogenes for a period of 8 weeks or more (dependent on cheese type). Cheese made without the addition of nisin contained unsafe levels of the organism within 1–2 weeks of incubation. Measurement of initial and residual nisin indicated a high level of retention over the 10‐week incubation period at 6–8°C, with only 10–32% nisin loss.