緑変缶詰カキの研究

概要

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Oyster, Crassostera gigas, from the coast of Hiroshima occasionally becomes green after being canned, and the phenomenon makes a trouble for the quality control of the products. The color usually develops around the digestive diverticula of the body, and the situation completely differs from those caused by such pollutants as heavy metals which makes the oyster also green. As the appearance of green oyster changes seasonally, a relationship was expected between the standing crops of dietary phytoplankton and the greening of the oyster. Solvent extracts of the oyster, its dietary phytoplankton and the feces were examined colorimetrically to compare their absorption spectra. The pigments extracted from the oyster were found consisting of chlorophyll and carotenoids. It was confirmed that the green pigments in the oyster are of plankton origin, and their total amount depends upon the amount of chlorophyll a contained in the suspension in environmental water. The green pigments deposited in the oyster body decreased when the oyster were kept in filtered water for a few days. The developed gonad covers the digestive diverticula portion to make the green color pigmentation rather invisible, which seems another reason why the green color differs between individuals as well as between the season.
公益社団法人日本水産学会の論文