Effects of transglutaminase on the gelation properties and digestibility of pea protein isolate with resonance acoustic mixing pretreatment

Our previous research confirmed that resonance acoustic mixing (RAM) pretreatment effectively improved the emulsification and water retention of commercial pea protein isolate (PPI), but significantly reduced its gel performance. This study aimed to investigate the effect of transglutaminase (TGase, 0.1 %, 0.2 %, 0.3 %, 0.4 %, and 0.5 %) on the gel properties and digestibility of PPI with RAM pretreatment (RAM-PPI). Results showed that moderate TGase (0.1-0.3 %) significantly increased the α-helix/β-sheet ratio, surface hydrophobicity and covalent crosslinking of protein molecules, enhancing the texture and digestibility of RAM-PPI gels. The SEM imaging demonstrated a fine, uniform and dense network structure with many pores in these RAM-PPI gels. However, excessive TGase (0.5 %) reduced the water holding capacity and intestinal digestibility of the RAM-PPI gels, mainly due to the excessive protein cross-linking and re-aggregation. These findings suggest that the combined treatment of moderate TGase with RAM can be a promising approach for the modification of plant-based proteins.