Effects of low NaNO(2) and NaCl concentrations on Listeria monocytogenes growth in emulsion-type sausage

OBJECTIVE: The objective of this study was to evaluate the effect of combinations of NaNO(2) and NaCl concentrations on Listeria monocytogenes (L. monocytogenes) growth in emulsion-type sausage. METHODS: Emulsion-type sausages formulated with different combinations of NaNO(2) (0 and 10 ppm) and NaCl (1.00%, 1.25%, and 1.50%) were inoculated with a five-strain L. monocytogenes mixture, and stored at 4°C, 10°C, and 15°C, under aerobic or vacuum conditions. L. monocytogenes cell counts were measured at appropriate intervals, and kinetic parameters such as growth rate and lag phase duration (LPD) were calculated using the modified Gompertz model. RESULTS: Growth rates increased (0.004 to 0.079 Log colony-forming unit [CFU]/g/h) as storage temperature increased, but LPD decreased (445.11 to 8.35 h) as storage temperature and NaCl concentration increased. The effect of combinations of NaCl and low-NaNO(2) on L. monocytogenes growth was not observed at 4°C and 10°C, but it was observed at 15°C, regardless of atmospheric conditions. CONCLUSION: These results indicate that low concentrations of NaNO(2) and NaCl in emulsion-type sausage may not be sufficient to prevent L. monocytogenes growth, regardless of whether they are vacuum-packaged and stored at low temperatures. Therefore, additional techniques are necessary for L. monocytogenes control in the product.