Characterization of protein isolates from different Indian chickpea (Cicer arietinum L.) cultivars

Protein isolates prepared by alkaline solubilization followed by isoelectric precipitation and freeze drying from desi (PBG-1, PDG-4, PDG-3, GL-769, and GPF-2) and kabuli (L-550) chickpea cultivars were evaluated for functional (water and oil absorption capacities, least gelation concentration, foaming capacity and stability) and thermal properties. Significant difference (P ⩽ 0.05) in properties of kabuli and desi chickpea protein isolates was observed. Kabuli chickpea protein isolate showed significantly (P ⩽ 0.05) higher ash (1.14%), protein (94.4%), L∗, ΔE value, oil absorption capacity (OAC) and lower water absorption capacity (WAC) than their corresponding desi chickpea protein isolates. The solubility-pH profile of different protein isolates showed minimum solubility in the pH between 4.0 and 5.0 and two regions of maximum solubility at pH 2.5 and 7.0. Foaming capacity of all protein isolates increased with the increase in concentration. Kabuli chickpea protein isolate showed the highest foam stability (94.7%) after 120 min of storage. The thermal properties of protein isolates from different chickpea cultivars were studied by differential scanning calorimetry (DSC). Protein isolates from both the chickpea types differed significantly (P ⩽ 0.05) in peak denaturation temperature (Td) and heat of transition (ΔH). Kabuli type protein isolate exhibited lower Td and ΔH value as compared to those from desi types. The interrelationships between characteristics of protein isolates showed a significant (P ⩽ 0.05) negative correlation of Td with protein content and OAC. It was also observed that cultivars with high fat content had high ΔH and lower WAC.