title: Survival of Escherichia coli O157:H7 during manufacture and storage of white brined cheese.
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 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.
authors.affiliation: Dept. of Nutrition and Food Technology, Faculty of Agriculture, Jordan Univ. of Science and Technology, P.O. Box (3030), Irbid, 22110, Jordan.
authors.forename: Tareq M
authors.initials: TM
authors.lastname: Osaili
authors.forename: Anas A
authors.initials: AA
authors.lastname: Al-Nabulsi
authors.forename: Amin N
authors.initials: AN
authors.lastname: Olaimat
authors.forename: Reyad R
authors.initials: RR
authors.lastname: Shaker
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taha
authors.forename: Richard A
authors.initials: RA
authors.lastname: Holley
mesh_terms: D002611:Cheese / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000302:isolation & purification / Q000502:physiology*; D005516:Food Microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007777:Lactobacillaceae / Q000302:isolation & purification / Q000502:physiology; D012492:Salts / Q000737:chemistry; D015014:Yogurt
chemical_list: D012492:Salts; C017082:brine
keywords: E. coli O157:H7; NaCl; cheese brine; lactic acid bacteria; white brined cheese