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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Residue Chemistry and Predictive Microbiology Research » Research » Publications at this Location » Publication #316884

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

Location: Residue Chemistry and Predictive Microbiology Research

Title: Modeling the effect of water activity, pH, and temperature on the probability of enterotoxin production by Staphylococcus aureus

Author
item Ding, Tian - Zhejiang University
item Yu, Yan-yan - Zhejiang University
item Hwang, Cheng-an - Andy
item Dong, Qing-li - University Of Shanghai
item Chen, Shi-guo - Zhejiang University
item Ye, Xing-qian - Zhejiang University
item Liu, Dong-hong - Zhejiang University

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2015
Publication Date: 1/1/2016
Citation: Ding, T., Yu, Y., Hwang, C., Dong, Q., Chen, S., Ye, X., Liu, D. 2016. Modeling the effect of water activity, pH, and temperature on the probability of enterotoxin production by Staphylococcus aureus. Journal of Food Protection. 79(1):148-192.

Interpretive Summary: Staphylococcus aureus is a toxin-producing pathogen that frequently causes food poisoning. This study developed a probability model of S. aureus enterotoxin production at different moisture (aw 0.86-0.99) and acid (pH 5.4 -7.0) levels and storage temperatures (10-30 degrees Celsius). The probabilities were fitted with a logistic regression to develop a model. The developed model describes the probability of enterotoxin production satisfactorily and showed that aw, pH, and temperature were significant factors affecting the probability of toxin production. The model may help manufacturers in selecting product pH, aw, and storage temperature to prevent S. aureus enterotoxin production to reduce the risk of S. aureus.

Technical Abstract: Staphylococcus aureus is a foodborne pathogen widespread in the environment and found in various food products. This pathogen can produce enterotoxins that cause illnesses in humans. The objectives of this study were to develop a probability model of S. aureus enterotoxin production as affected by water activity, pH, and temperature in a broth model and assess its applicability in food products. The probability of enterotoxin production by S. aureus was assessed in tryptic soy broth with 24 combinations of aw (0.86-0.99), pH (5.4 -7.0), and stored at temperatures of 10-30 degrees Celsius. The probabilities were fitted with a logistic regression to develop a probability model. The model had a concordant value of 97.5% and concordant index of 0.98, indicating that the model describes the probability of enterotoxin production satisfactorily. The model showed that aw, pH, and temperature were significant factors affecting the probability of toxin production. The model predictions were in good agreement with the observed values obtained from milk products. The model may help manufacturers in selecting product pH, aw, and storage temperature to prevent S. aureus enterotoxin production to reduce the risk of S. aureus.