Effect of Antioxidant-Rich Diets, Rearing, Harvesting, and Processing Conditions on Off-Odor Volatile Formation,...

Yellow perch (Perca flavescens) is a high-value aquaculture species, but variation in fillet nutritional composition and off-odor formation can limit product quality. This study evaluated how diets with plant-based antioxidants, rearing environment, use of heat shock, post-harvest processing, and fish weight affected off-odor volatile formation, lipid content, fatty acid profile, antioxidant activity, and vitamin E content in yellow perch fillets. Fish were fed camu camu, wheat flour, mixed starch, or commercial diets for 9 weeks, harvested with or without heat shock, and analyzed after frozen and refrigerated storage or baking. Volatiles were measured by selected-ion flow-tube mass spectrometry, while lipid content, antioxidant activity, vitamin E, and fatty acid profile were evaluated to characterize fillet composition and oxidative stability. Under standard harvest conditions, camu camu- and wheat-fed fish generally showed lower concentrations of lipid oxidation- and protein degradation-derived volatiles than mixed starch- and commercial-fed fish, especially after refrigerated storage or baking. These volatile differences were supported by differences in fillet composition and antioxidant status, with camu camu-fed fish showing the highest lipid content, while camu camu- and wheat-fed fish showed higher antioxidant activity than mixed starch-fed fish. Fatty acid profiling provided additional information on lipid composition and its potential relationship with lipid oxidation-derived off-odor formation. Heat shock increased volatile formation and reduced diet-dependent differences in the volatile profile. Heat shock also increased antioxidant activity across diets, eliminating diet-related differences in antioxidant activity. Rearing water systems and fish weight had limited effects on the volatile profile. These findings show that plant-based antioxidant diets can influence both nutritional quality and off-odor stability in yellow perch, particularly when combined with low-stress harvest and appropriate post-harvest handling.