Impact of hydrothermal processing of seeds on the composition, techno-biofunctionality, electrophoretic pattern, morphology and structural characteristics of dhaincha protein isolates

This study investigates the compositional and techno-functional properties of protein isolates derived from unprocessed (DPIc) and thermally processed (DPIp) dhaincha (Sesbania aculeata) seeds, with a focus on the effects of hydrothermal treatment (110 °C for 10 min) on their amino acid composition, structural characteristics, functional properties, and bioactive potential. Both DPIc and DPIp isolates demonstrated a high content of essential amino acids. Thermal processing significantly reduced antinutritional factors in DPIp, including the complete inactivation of lectins and a 75.36% reduction in trypsin inhibitor activity, without adversely affecting bioactive constituents or antioxidant capacity. SDS-PAGE analysis revealed distinct polypeptide bands in both isolates, with molecular weights ranging from 63–70 kDa, 25–35 kDa, 17–25 kDa, 11–17 kDa, and approximately 48 kDa. Structural analyses using ATR-FTIR, X-ray diffraction (XRD), and morphological assessments indicated minor conformational shifts in protein structure due to thermal processing. Functional studies revealed pH-dependent behavior, with enhanced hydration and surface-active properties post-processing. Both isolates exhibited a minimum gelation concentration of 14% at pH 7.0, though DPIp also formed gels at pH 4.0 and 9.0, unlike DPIc, which did not gel at these pH values. These findings suggest that thermal processing enhances the techno-functional properties of dhaincha protein isolates, potentially expanding their applications in food systems.