Abstract
Although more sustainable, feeding fish solely plant protein (PP) deteriorates their fillet quality more than animal counterparts, which additives can alleviate. This study investigated the effects of supplementing high PP diets with two additive mixtures on the fillet quality of rainbow trout (Oncorhynchus mykiss). Fish (~2.2g) were fed with four isonitrogenous (42 % CP) and isolipidic (20 % lipid) diets: fishmeal-based (FM), plant-based (PP), PP + A1 (PP with a mixture of krill meal, taurine, and organic selenium) and PP + A2 (PP with a mixture of proline, hydroxyproline, and vitamin C) diets, for seven months. Different diets significantly (p < 0.05) affected fatty acid composition, textural profile, hydroxyproline and collagen content, and genes related to collagen synthesis. The short-term (ice vs. -20 °C) and long-term (-20 °C, 90 days) storage conditions showed significant (p < 0.05) effects on different fillet quality attributes, including protein secondary structures. Overall, supplementing additive mixtures improved the fresh and stored fillet quality.