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The Inhibitory Effects of Varying Water Activity, pH, and Nisin Content on Staphylococcus Aureus Growth and Enterotoxin a Production in Whipping Cream
Author(s) -
Wang Tong,
Lin Lu,
Ou Jie,
Chen Min,
Yan Weiling
Publication year - 2017
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/jfs.12280
Subject(s) - staphylococcus aureus , nisin , enterotoxin , food science , chemistry , bacterial growth , microbiology and biotechnology , biology , bacteria , escherichia coli , biochemistry , antimicrobial , genetics , gene
To determine the appropriate method to inhibit Staphylococcus aureus growth in whipping cream, enterotoxin A‐producing S. aureus strain was inoculated into whipping cream and stored at 36 ± 1°C for 36 h under varying water activity ( A w ), pH, and nisin content. Duplicate samples were analyzed every 3 h to count the number of colonies by 3M Petrifilm™ Staph Express Count Plate, and the S. aureus enterotoxin A (SEA) was detected using ELISA kit (Tecra™). The modified Gompertz model was used to describe the S. aureus growth in whipping cream under various conditions. The results indicated that with the reduced A w of whipping cream after adding sorbitol, S. aureus growth and SEA production was more effectively inhibited compared with other methods. Compared with the cream with pH 5.5 or containing 0.5 g/kg nisin, SEA production appeared later in the cream containing 7% sorbitol. The cream containing 14% and 21% sorbitol could markedly inhibit S. aureus growth and no SEA could be detected during 36 h. The results from this study may be beneficial for cream manufacturers to improve the safety of their products. Practical Applications The purpose of this study is to find an appropriate method to inhibit Staphylococcus aureus growth and SE production whenever the whipping cream is contaminated with S. aureus during whipping, piping, and storage. The result showed that the water activity of the cream reduced by adding sorbitol had better effect against the S. aureus growth and SE production. The application of the result may be beneficial for manufacturers to formulate whipping cream that limit the ability of S. aureus to produce SE, thereby reducing the risk of staphylococcal food poisoning.