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KMID : 1011620170330060609
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Korean Journal of Food and Cookey Science
2017 Volume.33 No. 6 p.609 ~ p.615
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Viability of Escherichia coli and Yeast in Fruit Juices
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Kim Min-Su
Park Eun-Jin
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Abstract
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Purpose: This study monitored the growth of microbes contaminated in sterilized fruit juices on the market under two different storage conditions.
Methods: We selected three strains, Escherichia coli ubiquitously found in the environment, a yeast strain isolated from decayed citrus, and Streptococcus mutans causing dental cavities. Three types of fruit juices (citrus, apple and grape) obtained from retail stores were inoculated with the three strains and incubated at 4°C and 20°C for up to 12 weeks. Growth of the strains was monitored every week by culturing on media.
Results: The pH of the fruit juices ranged from pH 3.32 to 3.58. E. coli initially inoculated at 7.23 log CFU/mL disappeared from fruit juices by 3 weeks at 4°C and by 9 weeks at 20°C. The yeast inoculated at 5.7 log CFU/mL was reduced by 1-2 log CFU/mL at 4°C and 20°C for 12 weeks. No growth of S. mutans was observed within 4 days of incubation.
Conclusion: These data suggest that storage at room temperature could be more effective than cold storage for preventing microbial contamination of fruit juices. This study notes that microbial contamination by psychrophilic yeasts rotting citrus fruits could alter food quality during food processing and storage.
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KEYWORD
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fruit juice, Escherichia coli, yeast, mandarin juice, storage temperature
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