Structural and Functional Enhancement of Guar Meal Protein Concentrate Using High-Pressure Microfluidization

Guar protein concentrate, a byproduct of the guar gum industry, was treated by dynamic high-pressure microfluidization (DH-PM) at different pressure levels (60, 90, 120, and 150 MPa/single pass). The most pronounced modifications were observed at 120 MPa. DH-PM exerted intense shear forces, turbulence, cavitation, and high pressure, effectively disrupting protein aggregates, reducing particle size, and modifying protein conformation. As a result, the average particle size decreased significantly from 1786 ± 15 nm (control) to 1148 ± 10 nm (120 MPa). Structural modifications included partial unfolding, reduction in α-helix content (38 to 35%), an increase in β-sheet content (12.2 to 14%), and significantly increased surface hydrophobicity from 44.08 ± 3.40 to 286.72 ± 1.29 at 120 MPa, which was well-substantiated by FTIR and CD spectroscopy. These structural changes facilitated improved emulsifying activity and stability, along with a significantly increased protein solubility (from 12.17 ± 0.45% to 25.81 ± 0.32%). Protein digestibility increased significantly (P < 0.05) from 52.31 ± 0.87% to 78.72 ± 1.02%, with a protein digestibility corrected amino acid score of 50.38%. However, at 150 MPa, excessive shear stress and reaggregation led to a decline in the solubility and surface hydrophobicity. These findings demonstrate that DH-PM at optimized pressure levels (120 MPa) significantly enhanced guar protein’s quality and functionality by modifying protein conformation and improving dispersion, making it a promising alternative protein for application in the functional food industry and a sustainable valorization method for the guar meal.