Factors affecting the viability of Staphylococcus aureus and production of enterotoxin during processing and storage of white-brined cheese.
Journaljournal of dairy science3.333Date
2020 Jun 03
4 months ago
Journal Article
2020-Aug / 103 : 6869-6881
Al-Nabulsi AA 1, Osaili TM 2, AbuNaser RA 3, Olaimat AN 4, Ayyash M 5, Al-Holy MA 4, Kadora KM 6, Holley RA 7
  • 2. Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan; Department of Clinical Nutrition and Dietetics, University of Sharjah, Sharjah, PO Box 27272, United Arab Emirates.
  • 3. Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
  • 4. Department of Clinical Nutrition and Dietetics, Faculty of Allied Health Sciences, Hashemite University, Zarqa 13115, Jordan.
  • 5. Department of Food, Nutrition, and Health, College of Food and Agriculture, United Arab Emirates University, Al-Ain 15551, United Arab Emirates. Electronic address: [email protected]
  • 6. Department of Food Laboratories, Jordan Food and Drug Administration, Amman 11181, Jordan.
  • 7. Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
Staphylococcus aureus is a major foodborne pathogen that causes severe disease in humans. It is commonly found in milk and dairy products, particularly in fresh brined cheese. Our aim was to investigate the behavior of Staph. aureus and enterotoxin production during the storage of white-brined cheese prepared with or without a starter culture and stored in a 10 or 15% NaCl brine at 10°C and 25°C for 28 d. NaCl concentration, water activity, pH, and number of Staph. aureus and lactic acid bacteria were determined in cheese and brine. Only 1 of 4 Staph. aureus strains (ATCC 439) was positive for enterotoxin production, and its production was detected in unsalted UHT milk, but not in salted milk or in any of the cheese treatments held at 37°C for 1, 3, or 7 d. Staphylococcus aureus grew in the cheese stored in both brines at 10°C and 25°C, regardless of the presence of a starter culture, although the latter significantly reduced Staph. aureus growth in cheese or its brine at 10°C. Staphylococcus aureus numbers were increased by 2.26 and 0.47 log10 cfu/g in cheese stored in 10 and 15% NaCl brine, respectively, in the presence of starter culture, and by 2.78 and 2.96 log10 cfu/g, respectively, in the absence of starter culture at 10°C. Nonetheless, the pathogen grew, but at a lower number in the brines. The salt concentration of cheese stored in 10% brine remained at approximately 5% during storage; however, in 15% brine, the salt concentration increased to almost 8% (wt/wt) by 28 d. The addition of a starter culture, high salt concentration, low temperature, and pH (∼5.2) had inhibitory effects on the growth of Staph. aureus. Moreover, lactic acid bacterial numbers increased considerably in cheese and brine by d 28. The use of starter cultures, salt (15%), and low storage temperature (10°C) reduced the growth of Staph. aureus, and salt may have prevented enterotoxin production in white-brined cheese.
Keywords: Staphylococcus aureus lactic acid bacteria staphylococcal enterotoxin starter culture white-brined cheese
J Dairy Scijournal of dairy science
LocationUnited States

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