Effects of Dietary Replacement of Fish Oil by Vegetable Oil on Odor of Hepatopancreas and Gonads of Chinese Mitten Crab(Eriocheir sinensis)

In order to study the effects of dietary replacement of fish oil by vegetable oil on the odor quality of hepatopancreas of Chinese mitten crab,vegetable oil(soybean oil:rapeseed oil=3:1,W/W)was used to replace different levels of fish oil(0,50% and 100%)to make three kinds of feeds with equal nitrogen and fat(F1,F2 and F3)to feed adult female crabs for 70 days.In this study,the overall odor differences by using electronic nose were analyzed in combination with sensory evaluation,and odor substances were analyzed by gas chromatography-mass spectrometer-olfactometry. The results showed that electronic nose could effectively distinguish the odor profiles of the three groups of hepatopancreas and gonads of Chinese mitten crab. The meat flavor of the hepatopancreas and gonads in the F2 group was stronger than that of the other two groups,and the earthy smell was lowest by sensory evaluation. 57,39 volatile substances,25,17 olfactory substances were identified in the hepatopancreas and gonads,respectively,and the kinds of volatile substances in these two parts of the F2 group were more than that of the other two groups. Aldehydes contributed the most to the odor of these two parts,among which nonanal and decanal were the main odorants of these two parts,showing milky flavor and raw crab odor respectively. The use of the F2 group feed increased the olfactory intensity of the pleasant odor to a certain extent while reducing the olfactory intensity of the unpleasant odor. In summary,it was the most appropriate to use 50% vegetable oil in the feed instead of fish oil,which could improve the odor of the hepatopancreas and gonads while reducing the cost of breeding. The above results would provide a reference for the improvement of the odor quality of cultured Chinese mitten crabs and the development of fish oil substitute sources in fattening feed.