Investigation of transglutaminase incubated condition on crosslink and rheological properties of soy protein isolate, and their effects in plant-based patty application

The crosslink interaction and rheological properties of transglutaminase (TGas) on the soy protein isolate (SPI) and the effect on patty application were studied. The TGas concentration as 0, 1, 3, 5, or 10% without incubation, or incubation at 50 °C for 1 or 4 h were measured. The molecular size of the SPI tended to increase with TGas. However, there were no differences in the SDS-PAGE results between adding 5 or 10% TGas. The rheological properties of the SPI and TGas interaction showed shear-thinning behavior with n values less than 1. The increase of TGas concentration and incubation time increased the solid-like properties according to the storage modulus increased and tanδ decreased, especially for 5% TGas with 1 or 4 h incubation time. The plant-based patties composed of TGas at 0, 1, 3, or 5% and incubated at 25 °C/1 h, 25 °C/2 h, or 4 °C/24 h were investigated. The color changed with increasing TGas concentration and incubation time. The samples hardness tended to increase with higher TGas concentrations. Cohesiveness and springiness increased when incubated at 25 °C for 2 h, especially using 5% TGas. The rheological properties and the textural properties would be highly correlated with the concentration of TGas. The structural characteristics using confocal laser scanning microscopy showed the clustering of green colors representing protein components with 3 and 5% TGas addition that might have been due to the noticeable aggregation of the protein. Thus, the crosslinking between SPI and TGas affected rheological properties, texture and structure of the plant-based patties.