Probabilistic Model to Describe the Combination Effect of NaNO2 and NaCl on Salmonella Growth Response

Introduction: Because of health concern about sodium, low-NaNO₂ and low-NaCl meat products have been produced, but food safety for the products has not been evaluated.

Purpose: This study developed probabilistic models to describe Salmonella growth responses in low-NaNO₂ and low-NaCl meat products.

Methods: A five-strain mixture of Salmonella was inoculated in nutrient broth formulated with NaCl (0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, and 1.75%) and NaNO₂ (0, 15, 30, 45, 60, 75, 90, 105 and 120 ppm), and all samples were incubated at 4, 7, 10, 12, and 15°C under aerobic and anaerobic storage for up to 60 days. Growth (assigned the value of 1) or no growth (assigned the value of 0) for each combination was determined by turbidity. The growth response data were analyzed by a logistic regression to calculate the growth probability of Salmonella as a function of NaNO₂ and NaCl concentrations for each temperature. The predicted growth responses were compared with the growth response from frankfurters for validation.

Results: At 4 and 7°C, Salmonella growth was not observed at both aerobic and anaerobic conditions. Single application of low concentration of NaNO₂ did not inhibit Salmonella growth, but NaCl significantly (P < 0.05) inhibited Salmonella growth at 10, 12 and 15°C, regardless of presence of oxygen. When NaNO₂ was combined with NaCl, the probability of Salmonella growth was decreased. Validation result showed that concordance percentage between observed data and predicted data was 71%.

Significance: This study indicates that the developed probabilistic models should be useful in describing the combination effect of NaNO₂ and NaCl on inhibiting Salmonella growth in processed meat products.