The improvement and mechanism of gelation properties of mung bean protein treated by ultrasound

This work aimed to investigate effects of ultrasound treatment on structure and gelation properties of mung bean protein gel (MBPG). Structure properties were evaluated by surface hydrophobicity, free sulfhydryl group, SDS-PAGE, FTIR, intermolecular forces and SEM. And the gelation properties were characterized by rheological properties, textural properties and water holding capacity (WHC). Ultrasound treatment increased surface hydrophobicity and free sulfhydryl group of mung bean protein solution. SDS-PAGE showed that MBPG contained eleven protein bands, with the highest content of 48.8 kDa, and ultrasound treatment did not change the protein profiles of MBPG. Ultrasound treatment decreased α-helix and β-turn of MBPG, while increased β-sheet content. Solubility differences of MBPG in five solvents further demonstrated that ultrasound treatment enhanced hydrophobic interactions and disulfide bonds of MBPG, which were the main forces forming gel. SEM images manifested that ultrasound-treated MBPG had a denser and more uniform network structure than the control, especially at 300 W ultrasound treatment. MBPG treated with 300 W had the largest storage modulus (G′) (3931.7 Pa), hardness (8.38 N), chewiness (5.41 N), springiness (0.918), cohesiveness (0.766) and WHC (79.6%) compared with others. These results indicated that ultrasound treatment could improve gelation properties of MBPG, especially at 300 W.