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The use of high pressure processing in the oyster industry |
M. T. MORRISSEY, Dept. of Food Science & Technology, Oregon State Univ., Astoria Seafood Lab., 2001 Marine Dr., Rm. 253, Astoria, OR 97103-3420 High pressure processing (HPP) is a novel food processing technology which subjects liquid and solid foods to pressures between 100 and 800 MPa at ambient temperatures. The technology has attracted increased attention as a means of non-thermal treatment of raw or fresh foods for reduction of bacterial loads without causing significant changes in appearance, flavor, texture and nutritional qualities. This technology is being readily adapted and used by the oyster industry. Oysters are the most abundant harvested shellfish in the world. They are filter feeders and have a varied microbial flora which will eventually lead to spoilage and may, at times, pose a threat to public health. There have been several cases of severe illness associated with the consumption of raw oysters in the U.S. with the majority being attributed to Vibrio species. Studies have shown that HPP treatment is effective in reducing total bacterial load in oyster meats and that the process could be used for mechanically shucking oysters by detaching the adductor muscle from the shell. Optimum shucking pressures for releasing the adductor muscle from the shell range between 250-310 Mpa (time dependent) and caused minimum changes to sensory qualities as well as provide unique value-added products for the industry. Research and industry applications showed that HPP has become the newest and most promising method to provide Vibrio free raw oysters. Vibrio species are susceptible to HPP treatment at pressure levels between 200-350 Mpa and industry trials have shown that normal operating conditions are sufficient for elimination of V. vulnificus. V. parahaemolyticus strains have proven to be more resistant to HPP but can be reduced by several log numbers. This presentation will describe the research advances in HPP and discuss how the industry has used this information to incorporate the technology into their process systems.
Session 34, Applications of high pressure processing technology in the food industry: Case study
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