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Survival of Escherichia coli O157:H7 during Manufacture and Storage of White Brined Cheese
Author(s) -
Osaili Tareq M.,
AlNabulsi Anas A.,
Olaimat Amin N.,
Shaker Reyad R.,
Taha Mohammad,
Holley Richard A.
Publication year - 2014
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/1750-3841.12547
Subject(s) - starter , brine , food science , streptococcus thermophilus , escherichia coli , pasteurization , food preservation , chemistry , food microbiology , bacteria , ripening , lactic acid , lactobacillus , fermentation , biology , biochemistry , genetics , organic chemistry , gene
Escherichia coli O157:H7 is a major foodborne pathogen that causes severe disease in humans. Survival of E. coli O157:H7 during processing and storage of white brined cheese was investigated. Cheeses were prepared using pasteurized milk inoculated with a 4 strain E. coli O157:H7 cocktail (7 log 10 CFU/g) with or without yogurt starter culture ( Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus ) and stored in 10% or 15% NaCl brine at 10 and 21 ºC for 28 d. NaCl concentration, water activity ( a w ), pH, and numbers of E. coli O157:H7 and lactic acid bacteria (LAB) were determined in cheese and brine. E. coli O157:H7 was able to survive in cheese stored in both brines at 10 and 21 ºC regardless of the presence of starter LAB, although the latter significantly enhanced E. coli O157:H7 reduction in cheese or its brine at 10 ºC. E. coli O157:H7 numbers were reduced by 2.6 and 3.4 log 10 CFU/g in cheese stored in 10% and 15% NaCl brine, respectively, in the presence of starter LAB and by 1.4 and 2.3 log 10 CFU/g, respectively, in the absence of starter LAB at 10 ºC. The pathogen survived, but at lower numbers in the brines. The salt concentration of cheese stored in 10% brine remained about 5% during ripening, but in 15% brine, the NaCl level increased 1.6% to 8.1% (w/w) by 28 d. Values of pH and a w slightly decreased 1 d after exposure to brine and reached 5.5 to 6.6 and 0.88 to 0.94, respectively, in all treatments.