Effect of salt concentration on acid‐ and salt‐adapted Escherichia coli O157:H7 and Listeria monocytogenes in recombined nonfat cast cheese
2019
Wusimanjiang, Paerhati | Öztürk, Mustafa | Ayhan, Zehra | Çagri Mehmetoglu, Arzu
In Turkey, legislation reduced the salt content in fresh cheeses from 10% to 6.5% in dry matter (DM). This study investigated the effect of salt reduction on the fate of acid‐ and salt‐adapted Escherichia coli O157:H7 and Listeria monocytogenes, as well as the textural quality of recombined nonfat cheese. The cheese was manufactured using milk protein concentrate (85% protein) and skim milk powder (35% protein). After pasteurization and addition of starter culture (0.1%), cheese milk was inoculated with acid‐ or salt‐adapted pathogens (1 × 10³ cfu/g). Following salting (4%, 6%, 8%, or 10% in DM) and fermenting (24 hr/30 °C), the microbiological and textural properties of the cheese were analyzed during 8 weeks of storage at 4 °C. Salt concentration did not affect E. coli survival during storage (p > .05). Acid‐adapted L. monocytogenes and E. coli survived 1 week longer than the unadapted control. Cheese hardness was unaffected (p > .05) by the salt concentration. PRACTICAL APPLICATIONS: The results of the present study can be used to assess the risk of survival of acid‐ and salt‐adapted Listeria monocytogenes or Escherichia coli O157:H7 in nonfat cheese (with different salt concentration) produced from unpasteurized milk.
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