Microstructure and model solute transport properties of transglutaminase-induced soya protein gels: effect of enzyme dosage, protein composition and solute size

摘要

The diffusion of poly(ethylene glycol) (PEG) in transglutaminase (TGase) cross-linked soya protein gels as affected by enzyme dosage and protein composition was investigated. PEG with different molecular weights (M_w) varying from 6000 to 400 000 g mol~(-1) was selected. Results of this study revealed that the time-related release of PEG from gel slices was found to be controlled by Fickian diffusion process. For PEG with M_w 6000 g mol~(-1), the diffusion coefficients (D) were independent on the enzyme dosage and protein composition. However, for PEG with M_w ≥ 20 000 g mol~(-1), there were strong dependences of diffusion on the solute size and on the gel network microstructure revealed by scanning electron microscopy (SEM), where more density gel network with smaller pores resulted in lower D of PEG. Lower D values of PEG with M_w ≥ 20 000 g mol~(-1) were obtained in gels induced by 2 U g~(-1) TGase, and the D values increased with increasing 11S ratio in gels. Moreover, data also showed that the diffusion of PEG with larger size was more sensitive to the variation of gel network.