The Effects of Processing Methods and Storage on Cadmium Levels in Pacific Oysters (Crassostrea gigas)

Abstract

ABSTRACT The effects of processing and storage on cadmium (Cd) levels in Pacific oysters (Crassostrea gigas) were examined. The oysters were 2.75 yrs old and were analyzed for Cd at various points in the processing line including: shucked (S), shucked and drained (SD), and shucked, drained, washed and jar-packed (S-WJ). The effects of high pressure processing (HPP) followed by washing and jar-packing were also examined. Jar-packed oysters from groups S-WJ and HPP were held under refrigerated storage and were analyzed at 0, 5 and 10 days. Some processing methods had significant effects on the Cd levels in oysters. Draining nectar from the oysters resulted in significant increases in Cd concentrations, followed by significant decreases as a result of washing and jar-packing. HPP-treated oysters that were washed and jar-packed showed further decreases in Cd. Ten days of jar-packed storage resulted in a gradual decrease in wet weight Cd concentration for both the HPP (from 1.1 to 0.8 mg/kg) and the S-WJ groups (from 1.4 to 0.9 mg/kg). Total tissue Cd levels decreased significantly during storage of oysters in Group S-WJ, while tissue weights increased significantly. These findings suggest that changes in Cd concentration may have been due to a combination of a release of Cd by the oyster tissue and a dilution of the available Cd due to water uptake.