A Comparative Study of the Structural and Functional Properties of Chickpea Albumin and Globulin Protein Fractions

Plant proteins have gained increasing interest as viable substitutes for dairy proteins, primarily due to their favorable functional and nutritional properties. In this study, the impact of varying pH levels (pH 3.0, 5.0, 7.0, and 9.0) on the structural and functional characteristics of chickpea albumin and globulin was investigated. Amino acid composition analysis revealed that globulin exhibited higher levels of aromatic and hydrophobic amino acid residues, aligning with its higher surface hydrophobicity. Gel electrophoresis data demonstrated that globulin predominantly consisted of polypeptides ranging from 10 to 60 kDa, while albumin primarily featured 18 kDa polypeptides with fewer disulfide bonds. At all tested pH levels, the globulin fraction exhibited higher fluorescence intensity values compared to albumin. Particularly, at pH 3.0, both components displayed tryptophan and tyrosine emission peaks, but with increasing pH, the tyrosine emission peak gradually diminished. Circular dichroism (CD) analysis further elucidated that albumin predominantly consisted of α-helical structures, with varying β-sheet content dependent on pH variations. Notably, albumin displayed significantly higher protein solubility than globulin at all pH values. Furthermore, significant differences in emulsion stability were noted, particularly at a sample concentration of 50 mg/mL, where albumin consistently exhibited superior stability compared to globulin. Overall, these findings hold significant promise for utilizing plant proteins in diverse food and beverage applications, capitalizing on their versatility and advantageous attributes.