Comparative Effects of Dry and Wet Aging on Quality, Flavor Development, and Metabolomic Profiles in Grouper Fillets

Aging techniques are widely used to enhance meat quality; however, they are seldom applied to fish. This study investigated the effects of low-temperature dry and wet aging on the quality, flavor development, and metabolomic profiles of grouper (Epinephelus lanceolatus × E. fuscoguttatus) fillets. The fish fillets were aged at 2°C ± 1°C for 8 days, with samples collected every 2 days. Dry-aged fillets showed progressive dehydration and weight loss but improved water-holding capacity (WHC) and reduced cooking loss. By contrast, wet-aged fillets retained moisture but had higher cooking loss. Both methods showed initial pH increases followed by declines. Thiobarbituric acid reactive substances (TBARS) and volatile basic nitrogen (VBN) increased during aging but remained within acceptable limits. Dry-aged fillets had the highest free amino acid (FAA) content on day 4, with glutamic acid and arginine as major contributors. Inosinic acid significantly increased on day 2, supporting flavor improvement. Metabolomic analysis identified mannitol and pyridoxine as characteristic metabolites in dry aging and L-aspartate and pyroglutamic acid in wet aging. Our results indicated that both aging processes induce distinct metabolic pathways that contribute to flavor enhancement, alterations in the nutritional profile, and potential risks related to oxidative deterioration and food safety. In conclusion, aging improved grouper fillet quality through distinct biochemical mechanisms that promote the formation of flavor compounds. These findings demonstrate that aging is a promising approach for accelerating flavor development and value to fish products.