Effect of Sodium Chloride on the Thermal Resistance of Geobacillus stearothermophilus
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Abstract:
To determine the effect of sodium chloride on the thermal resistance of Geobacillus stearothermophilus at temperatures below 100℃, G. stearothermophilus bacterial suspensions of 107 CFU/mL were used as the initial cultures for heat treatment. After the center temperature of the suspension reached 70 ℃, 80 ℃, and 90 ℃, respectively, the corresponding death rates and residual concentrations of G. stearothermophilus in the suspensions, prepared using different concentrations of sodium chloride, were studied, and the inactivation models of each temperature and concentration of sodium chloride were preliminarily established based on the residual concentrations. The results indicated that the inactivation curves of G. stearothermophilus suspensions under all conditions could be fitted with the DoseResp model in Origin 8.0, and all coefficients of determination (R2) were above 0.96. Single factor analysis of variance was performed on the thermal death rate of G. stearothermophilus at different temperatures, different time points, and different concentrations of sodium chloride. The death rate in the control during the first 40 s reached 95% or more at different temperatures, and the death rate with different concentrations of sodium chloride at temperatures below 70 ℃ reached more than 95% during the first 120 s, more than 93% at 80 ℃ during the first 60 s, and 98% or more at 90 ℃ during the first 60 s. Therefore, different concentrations of sodium chloride had a protective effect on G. stearothermophilus, and the protective effect of 2% sodium chloride was more significant than that of the other concentrations of sodium chloride tested.
