Survival of Escherichia coli O157:H7 during Manufacture and Storage of White Brined Cheese |
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Authors: | Tareq M. Osaili Anas A. Al‐Nabulsi Amin N. Olaimat Reyad R. Shaker Mohammad Taha Richard A. Holley |
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Affiliation: | 1. Dept. of Nutrition and Food Technology, Faculty of Agriculture, Jordan Univ. of Science and Technology, , Irbid, 22110 Jordan;2. Dept. of Food Science, Faculty of Agriculture and Food Science, Univ. of Manitoba, , Winnipeg, R3T 2N2 Canada |
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Abstract: | 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 log10 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 (aw), 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 log10 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 log10 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 aw 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. |
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Keywords: | cheese brine E. coli O157:H7 lactic acid bacteria NaCl white brined cheese |
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