SENSITIVITY OF Vibrio parahaemolyticus TO SPICES AND ORGANIC ACIDS

Authors


  • I am grateful for the technical assistance of Kelly Jones and Brenda Vaughn. Gratis samples of essential oils were supplied by Mper Corp., North Bergen, N.J.

ABSTRACT

The effects of 13 dried spices added to growth media at concentrations ranging from 0.l–1.0% were studied with respect to their bactericidal activity against Vibrio parahaemolyticus. Rates of growth of V. parahaernolyticus in culture media containing essential oils of oregano, thyme, and sassafras and in media containing citric, ascorbic, and malic acids were determined. Survival of the organism in tomato sauce adjusted to pH 4.4–6.5 and incubated at 10, 22 and 35°C were examined. Dried oregano and thyme were highly toxic to V. parahaemolyticus when present in growth media at a concentration of 0.5%. Essential oils of oregano, thyme, and sassafras were bactericidal at a 100 μg/ml level. Growth curves were similar in media adjusted to identical pH values, regardless of whether citric, ascorbic or malic acid was used to attain these values. No viable V. parahaemolyticus were detected in inoculated tomato sauce adjusted to pH 4.4 and held 24 hr at 10 and 22°C or after 4 hr at 35°C. After 24 hr, only a slight reduction in viable cell count was noted in tomato sauce adjusted to pH 5.6-6.5.

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