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Growth and survival of E. coli O157:H7 during the manufacture and ripening of a smear‐ripened cheese produced from raw milk
Author(s) -
Maher M.M.,
Jordan K.N.,
Upton M.E.,
Coffey A.
Publication year - 2001
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2001.01232.x
Subject(s) - ripening , food science , raw milk , escherichia coli , inoculation , enumeration , food microbiology , biology , chemistry , bacteria , mathematics , biochemistry , horticulture , genetics , combinatorics , gene
M.M. MAHER, K.N. JORDAN, M.E. UPTON AND A. COFFEY. 2001 . Aims: The behaviour of Escherichia coli O157:H7 was studied during the manufacture and ripening of a smear‐ripened cheese produced from raw milk. Methods and Results: Cheese was manufactured on a laboratory scale using milk (20 l) inoculated with E. coli O157:H7, and enumeration was carried out using CT‐SMAC. From an initial level of 1·52 ± 0·03 log cfu ml –1 in the milk (34 ± 2 cfu ml –1 ), the numbers increased to 3·4 ± 0·05 log cfu g –1 in the cheese at day 1. During ripening, the numbers decreased to <1 cfu g –1 and <10 cfu g –1 in the rind and core, respectively, after 21 days, although viable cells were detected by enrichment after 90 days. The presence of E. coli O157:H7 in the cheese was confirmed by latex agglutination and by multiplex PCR. Conclusions: The results indicate that the manufacturing procedure encouraged substantial growth of E. coli O157:H7 to levels that permitted survival during ripening and extended storage. Significance and Impact of the Study: The presence of low numbers of E. coli O157:H7 in milk, destined for raw milk cheese manufacture, could constitute a threat to the consumer.