Comparative Analysis of Nutritional Quality in Fresh and Frozen Tilapia ( Oreochromis niloticus ) Fillet: A Focus on Region‐Specific Variations

ABSTRACT As tilapia ( Oreochromis niloticus ) is a globally important aquaculture species with high nutritional value, understanding the region‐specific nutrient quality variations during freezing is critical for optimizing post‐harvest quality preservation. This study systematically investigated region‐specific variations in nutritional quality between fresh and frozen tilapia fillets, focusing on dorsal (DM), belly (BM), and tail (TM) muscle segments. Proximate analysis revealed all regions retained high moisture (76.50–79.18% ww) and protein (18.39–20.88% ww) regardless of state. Freezing led to significant lipid reduction ( p < 0.05), most notably in TM. Fresh samples exhibited higher total and essential amino acid contents than frozen counterparts, while all muscle segments maintained favorable amino acid profiles. Polyunsaturated fatty acids (PUFAs) constituted the predominant fraction (36.71%–45.66%), with DM exhibiting peak levels in fresh state. Lipid quality indices confirmed the nutritional advantages of tilapia, particularly in fresh fillets which showed more favorable PUFA profiles and more favorable cardiovascular risk indices (i.e., lower atherogenicity index and thrombogenicity index) than frozen samples. Freezing depleted free amino acid content by 13.25% (DM), 15.22% (BM), and 20.19% (TM). Multivariate statistical analysis (principal component analysis PCA and orthogonal projections to latent structures discriminant analysis OPLS‐DA models) consistently demonstrated significant nutritional disparities between fresh and frozen samples, with DM exhibiting marked variations in the frozen group. Overall, fresh tilapia fillets, especially DM, demonstrated superior nutrient preservation.