Effect of Transglutaminase on Structure and Gelation Properties of Mung Bean Protein Gel

The aim of this study was to investigate the effect of transglutaminase (TGase) treatment on structure and gelation properties of mung bean protein gel (MBPG). Structure properties for MBPG were determined by surface hydrophobicity, free sulfhydryl groups, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectra (FTIR), intermolecular forces and scanning electron microscopy (SEM). And the gelation properties of MBPG were characterized by rheological properties, textural properties, and water holding capacity (WHC). TGase treatment reduced surface hydrophobicity and free sulfhydryl group content of MBPG. SDS-PAGE showed that TGase cross-linking caused the protein band of TGase-induced MBPG to become shallow or disappear, especially 50.1 kDa band. In addition, TGase treatment changed the secondary structure of MBPG, with a reduction in beta-sheet and an increase in beta-turn and random coil. Intermolecular forces analysis manifested that covalent cross-linking and disulfide bonds were the primary forces involved in TGase-induced MBPG, and TGase treatment limited non-covalent interactions. SEM images indicated that the network structure of TGase-induced MBPG was more compact with smaller and more uniform pores than that of the control, especially at 30 U/g. Compared with the control, storage modulus (G '), hardness, chewiness, springiness, cohesiveness and WHC of 30 U/g TGase-induced MBPG reached the maximum of 45537 Pa, 1337.59 g, 1111.43, 0.99, 0.93, 87.0%, respectively. The results of this study showed that TGase treatment was a reliable method to improve the gelation properties of MBPG, especially at 30 U/g.