Effect of Germination Time on Physicochemical, Electrophoretic, Rheological, and Functional Performance of Chickpea Protein Isolates

This study was carried out to investigate the physicochemical, functional, electrophoretic, structural, thermal, and rheological properties of protein isolates obtained from germinated chickpeas at different germination times (0, 12, 36, and 48 h). An increase in germination time changed lightness (58.57 to 61.44), whiteness index (1.25 to 15.29), protein isolate recovery (19.84 to 21.34%), protein content (85.08 to 87.78%), antioxidant activity (25.83 to 31.58%), in vitro protein digestibility (86.35 to 93.76%), and degree of hydrolysis (0 to 1.89%) of protein isolates extracted from chickpea seeds. Significant increases (p < 0.05) in water absorption capacity (3.08 to 4.82 g/g), oil absorption capacity (4.45 to 5.58 g/g), emulsifying capacity (43.47 to 45.61 m2/g), foaming capacity (58.74 to 69.48%), and foaming stability (60.37 to 64.86%) were observed for the protein isolates with an increase in germination time (0 to 48 h). Storage and loss modulus decreased with an increase in germination time (0 to 48 h) of protein isolates that behave like weak gel materials (G′ > G″). Power law, Herschel–Bulkley, Bingham, and Casson models showed the best fit to rheological data, with R2 being greater than 0.93. Protein isolates showed a significant decrease in onset temperature (91.86 to 80.45 °C), peak temperature (107.20 to 95.41 °C), and enthalpy (3.65 to 2.48 J/g) with an increase in germination time. The electrophoretic study showed a slight variation in band intensities corresponding to proteins with low and high molecular weight. An increase in the secondary structure of amide I showed a reduction of α-helices (21.52 to 19.87%) and β-sheets (57.45 to 53.52%) and an increase in β-turns (18.17 to 19.64%) and random coils (3.30 to 6.97%) in chickpea protein isolates after 48 h of germination.