Structures, functional properties and simulated digestion in vitro of Chickpea protein fractions

Chickpea proteins possess superior nutritional value, however, limited systematic research on their physicochemical and functional properties has constrained their effective utilization in the food industry. For the potential application of chickpea protein in the food industry, the structure, physicochemical attributes, and functional characteristics of chickpea protein fractions (crude protein (CP), albumin, globulin and glutelin) obtained via Osborne fractionation were assessed. Fourier Transform Infrared Spectroscopy (FTIR) and Circular Dichroism spectroscopy (CD) analysis revealed that random coil and β-turn constitute the predominant secondary structures, indicating that all four protein fractions possess abundant active binding sites for enzymes and exhibit stable conformations. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and differential scanning caborimetry (DSC) result elucidated that four protein fractions are characterized by small molecular weights (10–65 kDa) and excellent thermal stability with denaturation temperatures all exceeding 95 °C.The amino acid composition is dominated by aspartate, glutamate, glycine, and arginine. Meanwhile, albumin demonstrated excellent solubility, foaming capacity, water holding capacity (WHC), and oil holding capacity (OHC) due to its low surface hydrophobicity, and high total sulfhydryl content. Glutelin was shown to have notable emulsifying capacity, WHC, and OHC. Furthermore, in vitro simulated digestion analysis of four protein fractions were conducted, and the results showed that the antioxidant activities of the four protein fractions after simulated digestion in vitro were significantly enhanced in a concentration-dependent manner, with albumin exhibiting the highest activity, followed by CP, globulin, and glutelin. In summary, chickpea proteins, especially albumin and glutelin, display promising functional properties and antioxidant activities, providing an experimental basis for further research and development of chickpea proteins.