Species-Dependent Physicochemical Properties and Bioactive Performance of Freshwater Fish Crackers: Linking Protein-Starch Structuring and Antioxidant Mechanisms.

The development of bioactive rich functional snacks from freshwater fish is increasingly accepted in society. The goal of this research was to investigate the physicochemical, antioxidant, and structural properties of three types of crackers made from three different species of fish rohu (Labeo rohita), silver carp (Hypophthalmichthys molitrix), and tilapia (Oreochromis niloticus) with the same formulation and processing methods. The crackers made from silver carp exhibited the greatest linear expansion, together with the highest phenolic content, flavonoid content, and degree of starch-protein matrix structuring. The crackers made from rohu had the greatest retention of protein and were also able to absorb the least amount of oil, indicating that they had a more compact matrix structure. Tilapia crackers demonstrated a significantly lower amount of phenolic compounds. However, their radical-scavenging activity was greater than that of the other two fish. This suggests that heat-induced antioxidant peptide generation may occur during the baking process. Fourier transform-infrared (FTIR) spectroscopy confirmed protein unfolding for each of the three species, whereas x-ray diffraction (XRD) demonstrated the presence of semicrystalline starch organization for all three species. Using principal component analysis (PC1: 71.52%; PC2: 28.48%), it was possible to show the relationship between antioxidant chemistry, color attributes, and species differentiation (independent of proximate composition). These findings provide a mechanistic framework to develop functional freshwater fish snack products based on species of fish.