Kinetic analysis of the damage of bacterial spores induced by heat treatment

This study was aimed to quantitatively evaluate the damage to Bacillus spores subjected to heat treatment, relevant to food industry sterilization processes. The damage caused to heat-treated Bacillus spores was assessed by measuring the extension of the lag time in liquid cultures at 13 °C, fitted to a modified Gompertz model. Defining the damage index as the extension in lag time, we revealed that high-temperature, short-time heating resulted in greater damage to spores compared to low-temperature, long-time heating, under approximately 1-log 10 reduction conditions. This method can account for sublethal injury—which is often overlooked by conventional selective media methods—potentially leading to more accurate food safety assessments. The findings suggest that while high-temperature, short-time treatments achieve similar lethality as long-time treatments with low-temperature, the former may hinder spore recovery. This approach offers an alternative perspective for evaluating the impact of heating conditions on spore damage and recovery in food processing. • Developed a method using lag time extension to quantitatively evaluate heat-induced damage to Bacillus spores. • Suboptimal low-temperature liquid culture at 13 °C effectively distinguished differences in sublethal heat damage, aiding accurate evaluation. • High-temperature, short-time heating caused significantly greater damage to spores compared to low-temperature, long-time. • Developed damage index (D i ) based on lag time showed a strong linear correlation with heating temperature for Bacillus spores after 1D-reduction heat treatment.