New Zealand Journal of Marine and Freshwater Research abstracts

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The potential food poisoning hazard of Vibrio pamhaemolyticus in New Zealand Pacific oysters

G. C. FLETCHER

Division of Horticulture and Processing Department of Scientific and Industrial Research Mt Albert Research Centre Private Bag, Auckland New Zealand

Abstract The level of Vibrio parahaemolyticus was generally very low in Pacific oysters sampled from 4 New Zealand oyster farms between November 1982 and May 1983. Of the 149 samples collected, only one was found to contain greater than the 1000 organisms g~' regarded as the maximum allowable by international standards (International Commission on Microbiological Specifications for Foods 1982: Micro-organisms in Foods, Vol. 2. Academic Press, New York). V. parahaemolyticus was detected in 57% of the oyster samples, but 95% of these contained less than 10 organisms g~'. Maximum levels appeared to coincide with high water temperatures at the farm sites. Chilling, freezing, and depuration reduced V. parahaemolyticus numbers in oysters after harvest. However, holding at ambient temperatures (19-25°C) resulted in up to a 35-fold increase in organism numbers with a maximum after one day. The food poisoning hazard from V. parahaemolyticus in New Zealand-grown Pacific oysters thus appears to be minimal. Recommendations are made to keep harvested shellfish cool and to chill them as soon as practical.

Keywords Vibrio parahaemolyticus; food poisoning hazard; seafood; Pacific oyster; Crassostrea gigas; shellfish; depuration; storage; temperature; handling procedures; gasteroenteritis

New Zealand Journal of Marine and Freshwater Research, 1985, Vol. 19: 495-505 Received 8 November 1984; accepted 19 February 1985

PDF file of entire paper: medium quality (747K); (scanned from paper original: notes about this process)

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