Studies on the Structural Evolution, Functional and in Vitro Digestive Properties of Rice Glutelin during the Self-assembly of the Amyloid Fibril Aggregates

Protein self-assembly to form amyloid fibril aggregates is an important means to improve and broaden the functional properties of food proteins. In this study, we investigated the functional properties of protein structure evolution, viscosity and thermal properties during the self-assembly of rice glutelin amyloid fibril aggregates (RAFA) formed by heating at pH 2.0 and 85 %C for different times, and their digestive behaviors in vitro digestion simulation. The results showed that at pH 2.0 and 85 ℃, the high molecular weight subunits of natural rice glutelin were gradually hydrolyzed into small molecular peptides below 12 ku, and the !-sheet structure content of RAFA increased from (22.76 ± 0.49)% at 0 h to (32.11 ± 0.52)% at the peak 6 h with the extension of heating time, indicating that the formation of RAFA is a protein hydrolysis followed by peptide reorganization aggregation process. In addition, RAFA showed high thermal stability, with the Tmax value of the exothermic peak increasing from (70.34 ± 0.51)℃ at 0 h to (174.55 ± 0.34)℃ at 4 h of peak. The TEM results of in vitro digestion showed the same trend of fiber digestion for 6 h and 10 h of heat treatment. After 60 min of pepsin digestion, a part of long fibers with branched shape was enzymatically dissolved into short fibers, while larger aggregate particles were observed; with the reduction of fiber structure after pancreatic enzyme action, large aggregate particles were enzymatically dissolved into small aggregate particles, so RAFA exhibited pepsin resistance. This study provides a theoretical basis for the construction of novel foods using protein fiber aggregates. © 2023 Chinese Institute of Food Science and Technology. All rights reserved.