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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Microbial and Chemical Food Safety » Research » Publications at this Location » Publication #409580

Title: One-step analysis of growth kinetics of mesophilic Bacillus cereus in liquid egg yolk during treatment with Phospholipase A2: Model development and validation

Author
item AHMAD, NURUL - OAK RIDGE INSTITUTE FOR SCIENCE AND EDUCATION (ORISE)
item Huang, Lihan
item Juneja, Vijay

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2023
Publication Date: 12/3/2023
Citation: Ahmad, N., Huang, L., Juneja, V.K. 2023. One-step analysis of growth kinetics of mesophilic Bacillus cereus in liquid egg yolk during treatment with Phospholipase A2: Model development and validation. Food Research International. 176. https://doi.org/10.1016/j.foodres.2023.113786.

Interpretive Summary: B. cereus is a diverse group of pathogens that may affect the safety of liquid egg products. The mesophilic B. cereus may grow and produce enterotoxins during enzymatic treatment of liquid egg yolk (LEY) using phospholipase A2 (PLA2) to improve its emulsification capacity and thermal stability. This study was conducted to investigate the growth kinetics of mesophilic B. cereus during PLA2 treatment of LEY and to determine the minimum, optimum, and maximum growth temperatures as well the effect of temperature on growth rate. The result from this study may help the food industry to adopt proper processing conditions to prevent the growth of mesophilic B. cereus during LEY production.

Technical Abstract: Liquid egg yolk (LEY) is often treated with Phospholipase A2 (PLA2) to improve thermal stability. However, this process may allow certain pathogens to grow. The objective of this study was to evaluate the growth kinetics of mesophilic Bacillus cereus in LEY during PLA2 treatment. Samples, inoculated with B. cereus vegetative cells, were incubated isothermally at different temperatures between 9 and 50 degC to observe the bacterial growth and survival. Bacterial growth occurred between 15 and 48 degC, but not at 9 and 50 degC. The growth curves were analyzed using the USDA IPMP-Global Fit, with the no-lag phase model as the primary model in combination with either the cardinal temperatures model (CTM) or the Huang square-root model (HSRM) as the secondary model. While similar maximum growth temperatures (Tmax) were determined (48.4 degC for HSRM and 48.1 degC for CTM), the minimum growth temperature (Tmin) of the HSRM more accurately described the lower limit (9.26 degC), in contrast to 6.51 degC for CTM, suggesting that the combination of the no-lag phase and HSRM was used to describe the growth of mesophilic B. cereus in LEY. The Root Mean Square Error (RMSE) of model validation and development was < 0.5 log CFU/ml, indicating the combination of the no-lag phase model and HSRM could predict the growth of mesophilic B. cereus in LEY during PLA2 treatment. The results of this study may allow the food industry to choose a suitable temperature for PLA2 treatment of LEY to prevent the growth of mesophilic B. cereus.