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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF PREDICTIVE MICROBIAL MODELS FOR FOOD SAFETY AND THEIR ASSOCIATED USE IN INTERNATIONAL MICROBIAL DATABASES

Location: Residue Chemistry and Predictive Microbiology

Title: Comparative study of thermal inactivation kinetics of Salmonella spp. in peanut butter and peanut butter spread

Authors
item Li, Changcheng -
item Huang, Lihan
item Chen, Jinquan -

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 22, 2014
Publication Date: May 9, 2014
Citation: Li, C., Huang, L., Chen, J. 2014. Comparative study of thermal inactivation kinetics of Salmonella spp. in peanut butter and peanut butter spread. Food Control. 45:143-149 doi.org/10.1016/j.foodcont.2014.04.023.

Interpretive Summary: Peanut butter, if contaminated with Salmonella, must be pasteurized prior to consumption. This study was conducted to investigate the thermal inactivation kinetics of Salmonella in peanut butter and spread products, and investigate the thermal resistance of this pathogen. Kinetic models of bacterial survival were developed. The results of this study can be used by the food industry to develop effective thermal processes to pasteurize to peanut butter and spread products.

Technical Abstract: Peanut butter has been implicated in multi-state outbreaks of salmonellosis in recent years. Studies have shown that Salmonella exhibited increased thermal resistance in peanut butter. However, little is known about the effect of product formulation on the kinetics of survival of Salmonella during thermal treatment. Therefore, the objective of this research was to compare the thermal resistance of Salmonella in four commercially available peanut butter and spread products, and evaluate the effect of product formulation on the survival of this pathogen during heating. Four peanut butter and spread samples, including Omega 3 (A), regular fat (B), reduced sugar (C), and reduced fat (D), inoculated with a 6-strain cocktail of Salmonella spp., were heated at 70, 75, 80, 85, and 90 degrees C. Experimental results showed that the highest thermal resistance of Salmonella was found in the samples with reduced fat, while the least in the samples with Omega 3 formulation. No significant difference in the bacterial thermal resistance was observed in the regular fat and reduced sugar formulations. The Weibull survival model was used to describe the survival curves. Results showed that the average exponent (shape factor) of the model ranged from 0.38 to 0.662, suggesting progressively decreased rate of inactivation during heating. The scale (rate) coefficients of the model increased linearly with temperature. The calculated minimum lethal temperature for Salmonella was 55.8, 59.8, 59.5, and 63.9 degrees C in samples A, B, C, and D, respectively. No tail effect was observed. The results of this study suggest that proper formulation of peanut butter and spread may enhance thermal inactivation of Salmonella.

Last Modified: 12/27/2014
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