P1-85 Survival of Staphylococcus aureus on Dried Fishery Products as a Function of Temperature

Monday, July 23, 2012
Exhibit Hall (Rhode Island Convention Center)
Na Yoon Park, Kyung Hee University, Seoul, South Korea
Kyung Jin Min, Kyung Hee University, Seoul, South Korea
Hee Jin Park, Kyung Hee University, Seoul, South Korea
Junil Jo, Korea Food and Drug Administration, Osong, South Korea
SoonHo Lee, Korea Food and Drug Administration, Osong, South Korea
Ingyun Hwang, Korea Food and Drug Administration, Osong, South Korea
Kisun Yoon, Kyung Hee University, Seoul, South Korea
Introduction:   Among the imported and domestic dried fishery products at retail market in Korea, 33.8% was reported to be contaminated with S. aureus. Dried fishery products were recommended to be kept at 10°C for quality maintenance of the products at retail markets, but were very often sold at ambient temperature in convenience stores and traditional Korean markets.

Purpose:   The object of this study was to evaluate survival of S. aureus and production of Staphylococcal enterotoxin A on dried filefishes and julienned squid at 10, 24, and 35°C.

Methods:   Dried filefishes and julienned squid were inoculated with enterotoxin A producing S. aureus at a concentration of 106CFU/g, respectively, and packed into polyethylene bags for storage at 10, 24 and 35°C. At selected times after inoculation, the diluted samples were plated onto Baird-Parker agar in duplicate, and incubated at 35°C for 48 h. Production of Staphylococcal enterotoxin A in dried fishery products was analyzed using a TECRA SE visual immunoassay kit and ELISA reader.

Results:   S. aureus on both dried filefishes and julienned squid survived longer at 10 °C than 24 or 35°C. After 5 months storage, populations of S. aureus resulted in reduction of 1~1.7 at 10 °C and 5~5.5 log CFU/g at 24°C. At 35°C, S. aureus was undetectable on dried filefishes and julienned squid after 14 and 16 days, respectively. Toxin production was not increased during 5 months, regardless of storage temperature. Survival kinetic parameters of the observed data were also well fit to the Weibull equation (GIna FiT v1.5, R2>0.95). Shape(P) and scale(delta) values of the Weibull equations were further described in a secondary model as a function of temperature using second-order polynomial model.

Significance:   The quality of dried fishery products was better maintained at 10°C. However, the low storage temperature has more potential for S. aureus survival on dried fishery products than ambient temperatures and thus causes a potential safety risk of the dried fishery products.