A Study To Assess the Numbers and Prevalence of Bacillus cereus and Its Toxins in Pasteurized Fluid Milk
| Autor: | Saleema Saleh-Lakha, Shu Chen, Martha Fabri, Susan Lee, Gavin Downing, Bruce Keown, Kelly E. Shannon, Carlos G. Leon-Velarde |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
030106 microbiology Bacillus cereus Pasteurization Food Contamination Enterotoxin Biology Shelf life Microbiology law.invention Butterfat 03 medical and health sciences Enterotoxins law Prevalence Animals Food science fungi Raw milk biology.organism_classification Spore 030104 developmental biology Milk Cereus Food Microbiology Food Science |
| Zdroj: | Journal of food protection. 80(7) |
| ISSN: | 1944-9097 |
| Popis: | Bacillus cereus is a pathogenic adulterant of raw milk and can persist as spores and grow in pasteurized milk. The objective of this study was to determine the prevalence of B. cereus and its enterotoxins in pasteurized milk at its best-before date when stored at 4, 7, and 10°C. More than 5.5% of moderately temperature-abused products (stored at 7°C) were found to contain >105 CFU/mL B. cereus , and about 4% of them contained enterotoxins at a level that may result in foodborne illness; in addition, more than 31% of the products contained >105 CFU/mL B. cereus and associated enterotoxins when stored at 10°C. Results from a growth kinetic study demonstrated that enterotoxin production by B. cereus in pasteurized milk can occur in as short as 7 to 8 days of storage at 7°C. The higher B. cereus counts were associated with products containing higher butterfat content or with those produced using the conventional high-temperature, short-time pasteurization process. Traditional indicators, aerobic colony counts and psychrotrophic counts, were found to have no correlation with level of B. cereus in milk. The characterization of 17 representative B. cereus isolates from pasteurized milk revealed five toxigenic gene patterns, with all the strains carrying genes encoding for diarrheal toxins but not for an emetic toxin, and with one strain containing all four diarrheal enterotoxin genes (nheA, entFM, hblC, and cytK). The results of this study demonstrate the risks associated even with moderately temperature-abused pasteurized milk and the necessity of a controlled cold chain throughout the shelf life of fluid milk to enhance product safety and minimize foodborne illness. |
| Databáze: | OpenAIRE |
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