Physicochemical and functional properties of γ-aminobutyric acid-treated soy proteins

Gamma-aminobutyric acid (GABA) is a non-protein amino acid with various health benefits. GABA enrichment in soy products such as tempeh, doenjang, and soymilk have been reported. However, no study has explored how GABA interacts with soy proteins and affects their properties. The current study investigated the physicochemical and functional properties of soy proteins in a 4% (w/v) slurry treated with 0.2-1.0% of GABA at 80, 90, and 100 degrees C. The addition of GABA significantly (P<0.05) reduced the average particle size and increased the zeta-potentialand intrinsic fluorescence intensity of the soy protein slurries. GABA treatment resulted in concentration-dependent increases (P < 0.05) in soy protein solubility, viscosity, rheology, emulsifying and foaming properties. This study, for the first time, investigated the effects of GABA on the properties of soy proteins. The findings would be useful in soy product formulation when GABA is added as a functional ingredient.