Dietary vitamin C improves muscle hardness and springiness associated with collagen and elastin synthesis in grass carp (Ctenopharyngodon idella)

Abstract

This study explored the effects of dietary vitamin C on growth performance, flesh quality, and collagen and elastin content in adult grass carp (Ctenopharyngodon idella). A total of 540 fish (initial weight 585.00 ± 0.96 g) were randomly distributed into six groups, with three replicates per group and 30 fish per replicate. Fish were fed six experimental diets containing 4.01, 44.13, 83.47, 124.17, and 167.18 mg/kg L-ascorbyl-2-polyphosphate (C2PP), as well as 82.82 mg/kg ethylcellulose-coated ascorbic acid (EC-AA), for 9 weeks. The results indicated that C2PP supplementation (44.13–167.18 mg/kg) enhanced adult grass carp growth performance. It also increased muscle hardness, chewiness, and springiness, as well as crude protein and crude lipid content, while decreasing cooking loss and moisture content. Vitamin C supplementation increased collagen and elastin synthesis in adult grass carp through the activation of the transforming growth factor-beta (TGF-β)/mothers against decapentaplegic homolog (Smads), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (AKT)/target of rapamycin (TOR), La ribonucleoprotein domain family member 6 (LARP6), and Fibulin-5 signaling pathways. Concurrently, vitamin C could inhibit collagen and elastin degradation by upregulating tissue inhibitor of metalloproteinases (TIMPs). Based on percent weight gain (PWG), hardness, and chewiness, the dietary vitamin C requirements for adult grass carp were 107.05, 104.42, and 97.00 mg/kg, respectively. These results indicate that vitamin C can improve the flesh quality of grass carp by promoting collagen and elastin deposition.