Influence of microwave treatment on the structural and functional properties of soy protein isolate-fenugreek gum graft conjugate

This study investigated the effects of microwave-assisted glycation of soy protein isolate (SPI) with fenugreek gum (FG). After 3 min of microwave treatment (850 W), the SPI-FG conjugates exhibited significantly improved functionality. Specifically, the solubility in the isoelectric range (pH 4.5–5.5) increased from 35.17% to 68.56%. The emulsifying activity and emulsifying stability increased by 2.87-fold and 7.62-fold, respectively. The modified SPI also demonstrated enhanced thermal stability and antioxidant activity, with DPPH radical scavenging capacity increased by 7.28-fold. Structural analysis revealed that the optimal microwave treatment promoted protein unfolding and covalent bonding with FG, as evidenced by an increase in β-sheet content from 25.1% to 28.9% and a 180.86% rise in free sulfhydryl groups. However, excessive treatment (5 min) led to protein aggregation and decreased functional properties. This work provides a theoretical basis for efficient plant protein modification using microwave-assisted glycation.