Quality Change in Precooked Sardine during Frozen Storage

자숙 정어리육의 동결저장중의 품질변화

Qualify changes of the precooked frozen sardine (Sardinops melanosticta) during frozen storage were investigated by measuring extractable protein, expressible drip, available lysine and lipid oxidation as peroxide value. Fresh sardine was dressed, washed in chilled water, cooked in boiling water to have $55^{\circ}C\;and\;70^{\circ}$ at the center of the body, frozen at $-40^{\circ}C$, and finally stored at $-20^{\circ}C$ for 84 days. The quality factor mentioned above were determined in both ordinary and dark muscle at 14 day intervals through the period of storage. When cooked at $70^{\circ}C$, the changes in expressible drip were less than that of raw and the one cooked at $55^{\circ}C$. In observation of the extractability of muscle protein, no great change in extractable sarcoplasmic protein was observed, the extractable myofibrillar protein, however, showed a tendency to decrease during the period of frozen storage, accompanying the increase of the alkali-soluble protein. That was more excessive in ordinary muscle than dark muscle. Lipid oxidation of dark muscle was faster than that of ordinary muscle. Acid value was not changed, and peroxide value of the samples cooked at $70^{\circ}C\;and\;55^{\circ}$ was higher than that of raw at the early stage of the storage, after 40-50 day storage, it became lower than that of raw muscle.