Effect of Drying Methods on Physicochemical and Sensory Characteristics of the Nile Tilapia (Oreochromis niloticus) Fillets

This study evaluates the effects of sun drying, hot air drying, vacuum drying, and freeze drying on the quality characteristics of freshwater fish fillets. Proximate composition, moisture content, water activity (aw), lipid oxidation (TBARS), total volatile base nitrogen (TVB-N), rehydration ratio, color parameters (L*, a*, b*), texture profile analysis (TPA), and sensory attributes were systematically analyzed. Freeze drying resulted in the lowest moisture content and water activity, accompanied by reduced lipid oxidation and TVB-N values, indicating superior preservation of chemical stability. Sun drying exhibited higher residual moisture, elevated oxidative indicators, and greater protein degradation. Structural evaluation through rehydration capacity and texture measurements demonstrated that freeze-dried samples maintained a more porous matrix, leading to lower hardness and improved springiness compared to thermally dried samples. Color analysis revealed higher L* values in freeze-dried fillets, reflecting minimized non-enzymatic browning. Sensory evaluation confirmed that samples with lower oxidation levels and improved texture achieved significantly higher scores in aroma, flavor, and overall acceptability. Freeze drying reduced residual moisture to 6.92% and produced the lowest TBARS value (1.08 mg MDA/kg), while sun drying retained higher moisture (18.42%) and exhibited the highest oxidation level (2.84 mg MDA/kg). Freeze-dried samples also showed the highest rehydration ratio (3.76) and overall sensory acceptability (8.14). These findings provide a comprehensive comparative assessment of drying technologies and support evidence-based selection of processing strategies for high-quality dried freshwater fish products.