Effect of Nisin and Storage Temperature on Outgrowth of Bacillus cereus Spores in Pasteurized Liquid Whole Eggs
2025
Binita Kumari Goshali | Harsimran Kaur Kapoor | Govindaraj Dev Kumar | Subash Shrestha | Vijay K. Juneja | Abhinav Mishra
Pasteurization is used to ensure the safety of liquid whole eggs (LWEs) before commercial distribution: however, it is insufficient to inactivate the spore-forming bacteria Bacillus cereus. This study investigated the effect of nisin on the growth kinetics of B. cereus in LWE. Samples supplemented with 0&ndash:6.25 ppm of nisin were inoculated with a four-strain cocktail of heat-shocked B. cereus spores and incubated at isothermal temperatures of 15&ndash:45 °:C. The Baranyi model was fitted to all B. cereus isothermal growth profiles, generating maximum growth rate (µ:max) and lag phase duration (LPD). The extended Ratkowsky square root model described the temperature dependency of µ:max. A second-order polynomial model assessed the combined effects of temperature and nisin on the LPD of B. cereus in LWE. A tertiary model was developed and validated using three dynamic temperature profiles. Nisin significantly extended LPD at lower temperatures, while µ:max remained unaffected. Samples with 6.25 ppm of nisin inhibited growth for 29 days (average) at 15 °:C. Although the tertiary model accurately predicted growth rates, it underpredicted LPD. Adjusting h0 values for each experimental condition improved LPD prediction accuracy. The study&rsquo:s findings indicate that nisin is effective in inhibiting the growth of B. cereus spores in LWE, lowering the risk of illness.
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