Study on Modification Mechanism of Rice Protein Network Based on Sodium Pyrosulfite Combined with TGase

Abstract

Abstract In order to improve the quality of fermented solid bubble food of rice, unmodified rice dough (URD) was modified by sodium metabisulfite combinated with TGase. Sodium metabisulfite was used to break the disulfide bond in the protein, and then TGase was used to crosslink it, in order to change the state of strong rigidity and toughness of URD, poor starting ability and no chewiness of rice food. In this study, the effects of chemical combined enzyme modification methods on the mesoscopic, structural properties and bonding of URD and unmodified rice protein (URP) were explored, with wheat dough (WD) and URD as reference. The mechanical and nuclear magnetic analysis showed that the tan δ and texture characteristic index of modified rice dough (MRD) is closer to that of wheat flour, the content of weak bound water increased, and the structure became more compact. Modified rice protein (MRP) microstructure were more looser. Electrophoretic analysis (SDS-PAGE) showed that MRP would form a new aggregation form, so its degradation temperature also increased, and the average particle size became larger. The secondary structure of the protein changed, α-helix and β-corners increased, β-sheet was reduced, and there was no obvious change in irregular crimping. The contents of hydrogen bond, ionic bond and hydrophobic bond in MRP were significantly higher than those in URP, and the increase of ionic bond was the largest. The results showed that the modification method of sodium pyrosulfite combined with TGase could change the original network structure of URP, thus effectively regulating the viscoelastic balance of URD.