Abstract:

The change in the composition of volatile components in Crassostrea gigas before and after hydrolysis was
analyzed according to sensory evaluation, SPME-GC/MS analysis and ROAV (relative odor activity value). The effect of
ginger juice on lipid oxidation and flavor of oyster hydrolysates was studied. The results showed that the relative contents
of lipid oxidation products such as pentatal, 3-methyl-butanal, heptatal, (E)-2-nonenal, (Z)-4-heptenal and 3,5-octadien-
2-one, which were responsible for fishy and fatty odor, were increased to 5.09%, 1.6%, 1.3% and 0.5%, respectively. The
unpleasant smell of oyster protein hydrolysates might be mainly related to lipid oxidation during hydrolysis. However, after
addition of ginger juice, the unpleasant-odor compounds derived from fat oxidation such as trans-2-pentenal, nonanal, (Z)-4-
heptenal, and 2,3-octanedione were not detected. Meanwhile, the contents of 3-methyl-butanal, hexanal, and trans-2-hexenal
were reduced by 81.02%, 33.28% and 54.39%, respectively. The major volatile components of ginger such as geraniol,
citronellol, citral, p-cymene and linalool were detected in oyster protein hydrolysates, which contributed to the flowery,
lemon and orange flavor of the hydrolysates. Therefore, ginger juice had a significant contribution to the flavor improvement
of oyster hydrolysates.

Key words: oyster (Crassostrea gigas), hydrolysates, ginger, flavor