This paper investigated the effect of MTGase cross-linking on the structure of soymilk protein and the improvement of physicochemical properties, digestibility and potential allergenicity of traditional tofu.

Summary This study aimed to evaluate the effects of microbial transglutaminase (MTG)‐mediated modification on the structure, digestibility and immunoreactivities of glycinin. Glycinin was separated from soya bean and cross‐linked with MTG, and the sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) showed that the molecular weight of cross‐linked glycinin was higher than that of native glycinin. Individual MTG cross‐linking could maintain stable secondary structures and spatial structure. Sequential heat denaturation and MTG cross‐linking could promote the unfolding of protein structures and reduce their hydrophobicity. The digestibility of glycinin was decreased, and its immunoreactivities were increased because of MTG‐induced structural alteration, including primary and spatial structures.

This study investigated the effects of enzymatic deglycosylation following ultrasound pretreatment on structure and immunoreactivity of soybean 7S globulin. Soybean 7S globulin was pretreated by ultrasound (40 kHz, 300 W) and enzymatically deglycosylated by peptide-N-glycosidase F (PNGase F). Changes in structure of processed soybean 7S globulin were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, reversedphase high-performance liquid chromatography, ultraviolet absorption spectrum, circular dichroism spectrum, and surface hydrophobicity analysis. Enzyme-linked immunoabsorbent assay was used to evaluate IgE-binding ability. The results showed that the glycan moieties of soybean 7S globulin were effectively removed by PNGase F, which significantly modified protein structures including the secondary and tertiary structures of 7S globulin. Individual enzymatic deglycosylation could reduce IgE-binding capacity of 7S globulin, whereas enzymatic deglycosylation following ultrasound pretreatment enhanced its IgE-binding capacity. In conclusion, soybean 7S globulin treated by single enzymatic deglycosylation can reduce potential allergenicity and may be employed in hypoallergenic food preparation. ARTICLE HISTORY