The Impact of Drying Technologies and Thermal Processing on the Nutritional Profiles, Flavor Fingerprints, and Taste Attributes of Giant Freshwater Prawn (Macrobrachium rosenbergii)

This study systematically investigated the effects of vacuum freeze-drying (VFD) and hot-air drying (HAD), combined with cooking and seasoning, on the nutritional composition, volatile flavor fingerprints, and non-volatile taste profiles of giant freshwater prawn (Macrobrachium rosenbergii) meat. Proximate composition, amino acid and fatty acid profiles, electronic nose, electronic tongue, and GC-MS were employed to characterize the quality evolution across nine treatment groups. Results demonstrated that drying significantly concentrated proteins, lipids, and amino acids, yet the retention efficiency was highly process-dependent. In cooked prawn, VFD exhibited superior preservation of heat-labile amino acids and polyunsaturated fatty acids, whereas HAD induced greater fatty acid retention in raw material. Notably, cystine was identified exclusively in unseasoned cooked groups, suggesting heat-induced oxidative dimerization of cysteine, while its absence in seasoned samples indicated interference from Maillard-driven reducing conditions. Flavor analysis revealed divergent mechanisms: VFD primarily exerted a physical concentration effect, preserving endogenous fatty acid methyl esters, while HAD triggered intensive thermochemical reactions, generating nitrogenous compounds (e.g., N, N-dimethylmethanamine) and roasted markers. Electronic tongue analysis indicated that VFD-cooked prawn achieved an optimal umami-richness balance, whereas seasoning imposed a dominant salty-acidic mask over inherent sweetness. Collectively, VFD is recommended for premium ready-to-eat products prioritizing nutritional integrity and authentic flavor, while HAD suits products targeting intense roasted sensory characteristics. This study provides a mechanistic framework and practical guidance for drying technology selection in aquatic product processing.