Abstract
In order to elucidate the oxidative stabilities of mackerel lipids, lipids were extracted from ordinary muscle, dark muscle, skin (including subcutaneous adipose tissue) and viscera, and then stored at $30^{\circ}C$. The changes of lipids were examined periodically by measuring peroxide value (POV), thiobarbituric acid (TBA), weighing method, acid value (AV) and iodine value (IV), Fatty acid composition of lipids was analyzed by GLC. The results obtained are summerized as follows: The velocity of lipid oxidation during the storage was differ from the extracting part of the sample. It was laster in skin, viscera, dark muscle and ordinary muscle in the order. Ratio of polar lipid fractions in total lipids was ranged from 5 to $15\%$, and the highest result was observed in dark muscle. Main fatty acids of the lipids were $C_{16:0}$ acid ($22.0{\sim}25.9\%$), $C_{18:1}$ acid ($22.3{\sim}26.7\%$) and $C_{22:6}$ acid ($9.6{\sim}13.4\%$), and $C_{22:6}$ acid content ($\%$) was the highest in lipid from dark muscle, and the lowest in lipid from skin. Monoenoic acid content ($\%$) was higher in the non-polar lipid than in the polar lipid, on the contrary. polyenoic acid content ($\%$) was higher in the polar lipid than in the non-polar lipid. Polyunsaturated fatty acids of the lipids, $C_{20:5}$ acid and $C_{22:6}$ acid, decreased predominantly with oxidation during storage, while saturated acids, $C_{14:0}$ acid and $C_{16:0}$ acid, increased predominantly. The polar lipid fractions were oxidized much faster than the non-polar lipid fractions.
고등어 지질의 산화안정성을 밝히기 위하여 어체를 표피, 보통육, 혈합육 및 내장의 4부위와 총어체에서 지질을 추출하여, $30^{\circ}C$에 저장하여 두고 산가, 과산화물가, TBA가, 요오드가, 중량변화 및 지방산 조성 등의 변화를 경시적으로 조사하여 산화안정성을 검토하였는데, 그 결과는 다음과 갈다. 1. 저장 중 지질의 과산화물가, TBA가의 변화 및 중량변화등으로 보아 산화속도는 표피지질, 내장지질, 총지질, 혈합육지질, 보통육지질의 순으로 빨랐다. 2. 각 부위의 극성지질과 비극성지질의 비율은 혈합육지질의 극성지질이 $15.46\%$로 가장 많았고, 표피지질의 극성지질이 $5.35\%$로 가장 적었다. 3. 전지질의 지방산 조성은 각 부위 모두 $C_{16:0}$산, $C_{18:1}$산 및 $C_{22:6}$산이 많았으며, 고도불포화산인 $C_{22:6}$산은 혈합육지질이 가장 많았고 표피지질이 가장 적었다. 4. 극성지질과 비극성지질의 지방산 조성에 있어서 $C_{16:1}$산 및 $C_{18:1}$산의 monoene산은 극성지질이 비극성지질에 비하여 낮았으며, $C_{20:5}$산 및 $C_{22:6}$산의 polyene산은 극성지질이 비극성지질보다 높았다. 5. 저장 중 지방산 조성의 변화는 polyene산 특히, $C_{20:5}$산 및 $C_{22:6}$산이 현저한 감소를 보였으며, $C_{14:0}$산 및 $C_{16:0}$산의 포화산의 증가가 두드러졌고 polyene산의 감소는 극성지질이 비극성지질보다 감소 속도가 빨랐다.