High-pressure treatment for shelf-life extension and quality improvement of oysters cooked in a traditional Taiwanese oyster omelet.

Whole oysters were processed using high-pressure (HP) treatment at 250 and 300 MPa for 0 to 10 min and stored at 4°C for up to 28 days. HP-treated oysters and untreated oysters were evaluated for lipid oxidation, growth of microorganisms, and sensory characteristics after cooking at 160°C for 90 s. Microbial counts after HP treatment revealed that the bacterial load was initially reduced at all pressures. HP-treated oysters had significantly higher pH and moisture (P < 0.05) relative to control (untreated) oysters during storage. HP treatment increased lipid oxidation with unpleasant odor during storage compared with the control. HP treatment decreased redness but did not significantly affect the brightness and yellowness of cooked oysters. From tests of mechanical properties, 300 MPa-treated oysters after cooking had significantly increased toughness as measured by cutting force. HP-treated oysters after cooking received higher quality scores than did the control during the storage trial. Results indicated that 300 MPa for 2 min is the optimum HP treatment that results in oysters most acceptable for oyster omelets during storage at 4°C, and this treatment may extend the shelf life of these oysters to 21 days.