Exploring the dietary impacts and potential metabolic mechanisms of astaxanthin in common carp (Cyprinus carpio)

This study investigated the dietary effects and metabolic mechanisms of astaxanthin (Ast) in common carp (Cyprinus carpio). Supplementation with 100 mg/kg Ast resulted in a significant 19.83 % increase in growth. Data from the electronic tongue indicated that dietary Ast enhanced fillet sweetness while reducing bitterness and saltiness. Colorimetric and computer vision analyses showed a shift in fillet color toward yellow-red (amber) hue, with a* values rising by up to 59.93 % (redness) and b* values by 40.84 % (yellowness). Carotenoid quantification revealed that Ast was metabolized into violaxanthin (0.23 ± 0.07 μg/g) and neoxanthin (0.19 ± 0.05 μg/g), with this conversion reaching a plateau at 100 mg/kg. These carotenoids were key contributors to the observed color changes. Based on structural analysis and inverse docking, potential metabolic pathways for Ast conversion are proposed, including steps from Ast to violaxanthin and neoxanthin. In conclusion, dietary Ast improves the flesh quality of common carp.