Physicochemical, morphological and functional properties of protein isolates obtained from four fish species

In this study, we investigated the physicochemical, morphological and functional characteristics of fish protein isolates (FPIs) prepared from four fish species through alkali solubilization and isoelectric precipitation. Significant differences were observed in the protein content, physicochemical, morphological and functional characteristics among FPIs. Morphology and particle size analysis revealed a significant difference in the shape and size of FPIs. Lipid oxidation of FPIs varied between 0.206 and 0.305 mg MDA/kg. Furthermore, all FPIs exhibited two broad diffraction peaks at ~ 8.6° and 19.3°, revealing their amorphous nature. A significant difference was observed in the thermal properties of selected samples, including T0, TP, TC, and ΔH values. T0, TP, TC, and ΔH of the endothermic transition varied in the range of 40.9–43.0 °C, 64.1–66.2 °C, 99.1–100.6 °C, and 237.1–267.2 J/g, respectively. All FPIs exhibited high water/oil absorption capacity, emulsifying capacity, foam stability and foaming capacity, signifying proteins potential to act as functional ingredients in the food industry.