Combining Alcalase hydrolysis and transglutaminase-cross-linking improved bitterness and techno-functional properties of hypoallergenic soybean protein hydrolysates through structural modifications

Alcalase hydrolysis of soybean proteins was shown effective in degrading epitopes, but with a significant loss of tastes and functional properties. In this study, the combined use of controlled Alcalase hydrolysis and transglutaminase (TGase)-cross-linking was used to produce hypoallergenic soybean protein hydrolysates (SPHs) with improved flavor and techno-functional properties. Through establishing the kinetic model of heterogeneous enzymatic processes, SPHs with different degrees of hydrolysis (2.5-10.0%) were obtained and polymerized by TGase to yield products with various peptide components. Results showed that post-hydrolysis cross-linking rearranged the (poly)peptides in SPHs via glutaminyl modifications. Following TGase-treatments, due to the masking of bitter-active peptides and free amino acids, the bitterness of SPHs was significantly reduced with a slight improvement in the overall flavor. Furthermore, TGase-cross-linking rescued multiple technofunctionalities of SPHs, particularly their emulsifying and foaming properties. Using sera from soybeanallergic individuals, it was evidenced that TGase-addition did not generate neoallergens and the residual allergenicity of SPHs was not distinctly affected. The final products maintained 44-71% reduction in the IgE-binding levels in comparison to the unhydrolyzed protein. Combining limited Alcalase hydrolysis with TGase-crosslinking provides a feasible way to produce hypoallergenic soybean ingredients with desired flavor and functional attributes.

Automated summary

Combining controlled Alcalase hydrolysis with TGase-crosslinking effectively produces hypoallergenic soybean protein hydrolysates with improved flavor and functional properties. TGase treatment significantly reduces bitterness and enhances overall flavor of the hydrolysates while also improving emulsifying and foaming properties. The addition of TGase does not generate new allergens and does not distinctly affect the residual allergenicity of the hydrolysates.