Effects of dietary supplementation of a mixture of ferulic acid and probiotics on the fillet quality of Megalobrama amblycephala fed with oxidized oil

To investigate the effects of feed composition on the quality of fillets, Megalobrama amblycephala were fed three diets containing either soybean oil (S group) or oxidized soybean oil (OS group), and oxidized soybean oil supplemented a mixture of ferulic acid and probiotics (BS group) for 8 weeks. After the feeding trial, fish fillets were collected for determining flavor nucleotides and free amino acids (FAAs). In addition, gas chromatography-ion migration spectrometry (GC-IMS) was used to analyze the volatile components and flavor profile in the fillets. The results showed that oxidized soybean oil contributed to the accumulation of off-flavor nucleotides such as hypoxanthine (Hx), hypoxanthin riboside (HxR), and umami-related FAAs. Mixtures of ferulic acid and probiotics promoted the accumulation of umami nucleotides, such as guanosine monophosphate (GMP) and inosine monophosphate (IMP), and off-flavor FAAs. The content of GMP and IMP in BS group was significantly (P < 0.05) higher than that in S group, while Hx and HxR showed the minimum value in S group and were significantly (P < 0.05) lower than that in OS and BS group. The content of glutamic acid in OS group was significantly (P < 0.05) higher than that in the other two groups, but phenylalanine, isoleucine and leucine, three off-flavor FAAs, had the highest values in BS group and were significantly (P < 0.05) higher than that in S and BS groups. The fingerprints of GC-IMS presented that the volatile substances, such as aldehydes, ketones, and esters, were significantly different in responding to the dietary compositions. The peak expression of 2-octanol in OS group was the highest and significantly (P < 0.05) higher than that in the other two groups, while the peak expression of ethanol in S group was significantly (P < 0.05) higher than that in OS group but significantly (P < 0.05) lower than that in BS group. Both nonanal and pentanal had the highest peak expression in OS group, which was significantly (P < 0.05) higher than that in S group. 2-heptanone-D and acetone are ketones. The peak expression level of 2-heptanone-D in OS group was significantly (P < 0.05) lower than that in BS group but significantly (P < 0.05) higher than that in S group, while acetone expression level in OS group was significantly (P < 0.05) lower than that in the other two groups. The peak expression of ethyl formate as an ester in BS group was significantly lower than that in S and OS groups. In general, the fish fillet quality of M. amblycephala is affected by dietary lipids. Dietary mixture feed additive of ferulic acid and probiotics (Aspergillus oryzae and Lactobacillus plantarum) increased the contents of the flavor substances in fish meat, especially flavored nucleotides, ketones, and esters.