Dietary tea polyphenols change flesh quality with dose-related manner in the GIFT tilapia fed with a high-fat diet

In aquaculture, the wide use of high-fat diet (HFD) could save protein and reduce feed costs, but also cause lipid deposition and impair flesh quality in fish. We hypothesized that tea polyphenols (TP) could alleviate the adverse effects of HFD on flesh quality in fish; thus, in the present study, GIFT tilapias were fed with control diet (60 g/kg fat), HFD (120 g/kg fat) and the HFD supplemented with two doses of TP (50 and 200 mg/kg, respectively) for 8 weeks. As compared with the control, the HFD feeding significantly increased lipid deposition and decreased monounsaturated fatty acids, muscle fibre diameter and density, and collagen content in muscle. Compared to the HFD group, the supplementation of TP in HFD increased fish growth and muscle essential amino acid content and reduced muscle contents of nonessential amino acids and delicious amino acids. More specifically, the low-dose TP increased muscle fibre density, springiness, gumminess and chewiness compared to HFD, while the high-dose TP mainly increased muscle fibre diameter and muscle collagen content. Taken together, this study indicates that the dietary supplementation of TP could alleviate most of the adverse effects caused by HFD in flesh quality in a dose-dependent manner.