Survival of Salmonella Serovars Introduced as a Post-Aging Contaminant During Storage of Low-Salt Cheddar Cheese at 4, 10, and 21°C

Document Type

Article

Journal/Book Title/Conference

Journal of Food Science

Issue

76

Publication Date

2011

First Page

616

Last Page

621

Abstract

The microbiological stability of low-salt cheese has not been well documented. This study examined the survival of Salmonella in low-salt compared to regular salt Cheddar cheese with 2 pH levels. Cheddar cheeses were formulated at 0.7% and 1.8% NaCl (wt/wt) with both low and high-pH and aged for 12 wk resulting in four treatments: 0.7% NaCl and pH 5.1 (low-salt and low-pH); 0.7% NaCl and pH 5.5 (low-salt and high-pH); 1.8% NaCl and pH 5.7 (standard-salt and high-pH); and 1.8% NaCl and pH 5.3 (standard-salt and low-pH). Each treatment was comminuted and inoculated with a 5-serovar cocktail of Salmonella at a target level of 4 log CFU/g, then divided and incubated at 4, 10 and 21 °C for up to 90, 90, and 30 d, respectively. Salmonella counts decreased by 2.8 to 3.9 log CFU/g in all treatments. In the initial period of survival study, standard-salt treatments exhibited significantly lower Salmonella counts compared to low-salt treatments. The pH levels did not exhibit obvious significant effect in the Salmonella survival in low-salt treatments. Salmonella counts declined gradually regardless of a continuous increase in pH (end pH of 5.3 to 5.9) of low-salt treatments at all study temperatures. Salmonella counts were reduced faster at 21 °C storage. Although there were significant reductions in Salmonella counts, the treatments demonstrated survival of Salmonella for up to 90 d when stored at 4 or 10 °C and for up to 30 d at 21 °C, the need for good sanitation practices to prevent postmanufacturing cross contamination remains.

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