Evaluation of extraction efficiency and quality of common kilka fish oil (Clupeonella cultriventris caspia) extracted at different times of hydrolysis with alcalase enzyme

In this study, the effect of different hydrolysis times (45, 90, 135, 180, and 225 minutes) by alcalase enzyme on the yield and quality of oil extracted from common kilka fish (Clupeonella cultriventris caspia) was investigated. The results showed that the highest extraction yield (40.41%) was in the hydrolyzed treatment for 135 minutes, which was not significantly different from other treatments. The qualitative indices of TBA, FFA, and CD of the extracted oils increased by increasing hydrolysis time, so the highest value of the mentioned indices was at 225 minutes, while the highest value of the PV index was at 180 minutes. Because the treatment of oil extracted in 45 minutes had lower values in the investigated oxidative spoilage indicators, it was selected as the treatment. The composition of its fatty acids was investigated, and it was found that monounsaturated fatty acids were the predominant fatty acids. Also, the amounts of saturated and polyunsaturated fatty acids did not show significant differences (p < 0.05). According to the obtained results, it was found that different hydrolysis times have different effects on the yield and quality of the obtained oil. Therefore, more research and studies are needed to fully investigate the effect of hydrolysis time on the quality characteristics of the oil extracted from Kilka fish.