Deep eutectic solvent-assisted extraction enhances functionality of yellow split pea protein: A sustainable approach...

The aim of this study was to evaluate the extraction efficiency, physicochemical, and functional properties of yellow pea protein (YPP) using deep eutectic solvents (DESs), and to assess the effect of DESs on alcalase activity and the hydrolysis of YPP. Proteins extracted with DESs exhibited higher purity than those obtained by alkaline extraction (>93% vs. 70%). Among the DES systems, DES-2 (choline chloride: urea: water, molar ratio 1:2:1) showed the highest protein extraction efficiency (approximately 72 ± 2%) and enhanced relative Alcalase activity to approximately 116.9%. YPP was purified by dilution with acidified water (1:40 v/v), followed by centrifugation. DES-2-extracted YPP (DES-YPP-2) exhibited higher band intensity, particularly in the higher molecular weight regions, lower fluorescence intensity, and greater intensity of characteristic amide bands than alkaline-extracted YPP, as evidenced by SDS-PAGE, fluorescence spectroscopy, and FTIR analyses, respectively. DES-YPP-2 also showed a lower zeta potential (∼ -0.2 mV), reduced particle size (824 ± 31 nm), and a higher contact angle (θ = 73°), indicating significant changes in the physicochemical properties of the DES-extracted protein. The increased solubility of DES-extracted protein (up to 15%) and the consequently greater stability of its emulsion and foam, when compared to alkaline-extracted YPP, confirmed the results of the structural and physicochemical analyses. These findings demonstrate that DES-2 has a strong ability to extract high-molecular-weight globulin proteins. Furthermore, this approach supports the valorization of yellow split pea, an underutilized agricultural by-product, into value-added protein ingredients.