Sustainable Utilization Technology for Improving the Freshness of Oysters—Development of Alkaline Electrolysis Seawater Depuration System

Abstract

The main purpose of this study is to study the effect of live oysters on various quality indicators after alkaline electrolytic seawater depuration. The depuration treatments were carried out for 12 h at temperatures of 5 °C, 10 °C, 15 °C, and 20 °C, pH = 9, 10, and 11, respectively. The total aerobic plate count (TAPC) of oyster meat was reduced from about 5.2 ± 0.4 log CFU/g to below detection limits when the oysters were depurated in pH = 11 alkaline electrolytic seawater for 9 h at 5 °C and 12 h at 10 °C. At the same pH value, the lower the seawater temperature, the lower the amount of TAPC, and it decreased with the increase in depuration time. After the oyster had been depurated, the chemical components contained in the oyster meat, such as protein, crude fat, and glycogen, did not change differentially. On the other hand, each group of live oysters (4 individuals) spat out an average of about 690–695 ± 0.4 mg of impurities and dirt. These are new achievements and discoveries. When the depurated oyster meat was stored at a low temperature, the freshness period could be extended to 21 days, which is much longer than the 5 days of the un-depurated oyster meat, and this is a significant difference. If coupled with vacuum packaging, the effect will be even better.