Mechanistic insights into the effects of controlled enzymatic hydrolysis on the binding behaviors between soy protein isolate and off-flavor compounds.

Regulating volatile compounds release through protein structural modification can influence food sensory properties. This study investigated the effects of controlled enzymatic hydrolysis (CEH) on the release of off-flavor compounds identified in soybean protein isolate (SPI) and revealed its potential mechanism of influence. CEH treatment significantly reduced the release of aldehydes, particularly (E, E)-2,4-decadienal, by inducing the unfolding of SPI unfolding. This structural modification exposed additional binding sites, thereby increasing the affinity of SPI for aldehyde compounds and effectively limiting aldehyde volatility. Multi-spectroscopic techniques, surface hydrophobicity, and dynamic light scattering (DLS) analyses confirmed these structural changes. Isothermal titration calorimetry (ITC) analysis suggested that non-covalent interactions, dominated by hydrogen bonds and hydrophobic interactions, were the primary factors driving these changes, as further confirmed by molecular dynamics (MD) simulations and independent gradient model (IGM) analysis. Additionally, proteomics revealed that covalent binding, including Michael addition and Schiff base reactions, also influenced the aldehydes release.