Abstract: The water distribution, texture properties and microstructure of modified soybean protein isolate (SPI) gels induced by transglutaminase (TGase) were detected using a low-field nuclear magnetic resonance (LF-NRM) instrument, a texture profile analyzer (TPA), and a differential scanning calorimeter (DSC). The obtained results showed that increasing percentage of 11S globulin in modified SPI was significantly correlated with the moisture distribution, texture properties and microstructure of SPI gels. The transverse relaxation time (T2) decreased first and then increased with increasing the 11S globulin percentage from 60% to 80% (m/m). Besides, the viscosity, hardness and chewiness all declined. The thermal stability of SPI gels showed an initial increase followed by a decrease, and the lowest enthalpy change (ΔH) was observed with 70% 11S globulin, indicating reduced water loss. The microstructure of SPI gels with 60% and 70% 11S globulin presented a flat surface with smaller and relatively homogenous pits.

Key words: modified soybean protein isolate, low-field nuclear magnetic resonance, moisture distribution, texture profile analysis properties, microstructure