Use of high-pressure processing for oyster shucking and shelf-life extension

Whole Pacific oysters (Crassostrea gigas) were processed using high-pressure processing (HPP) treatment from 207 to 310 MPa at 0, 1, and 2 min and stored at < 4 degrees C and evaluated over 27 d. The pH of HPP samples decreased slightly from 6.3 to 5.8 during storage while the control (hand-shucked oysters) dropped to pH 4.1. Moisture content of the controls decreased slightly while HPP samples increased slightly. Pressure treatment did not significantly inhibit lipase activity during the shelf-life study. HPP reduced initial microbial load by 2 to 3 logs and counts remained at a reduced level through the storage study. Descriptive evaluation showed that HPP-treated oysters received higher quality scores than controls during the storage trial.