Application of transglutaminase for quality improvement of whole soybean curd

To improve the quality of whole soybean curd (WSC), effects of compound coagulants consisting of calcium chloride (CaCl₂) and transglutaminase (TGase) were investigated. The results showed that TGase modified the water distribution and reduced the cooking loss of WSC, accompanying with increased water holding capacity. The bloom value of WSC was upgraded as the TGase concentration increased. Although certain sensory parameters showed different scores in groups, the overall acceptability of 1500 ppm group was the highest. TPA test suggested that hardness, springiness and chewiness were promoted by TGase significantly. Smooth appearance of WSC was observed, resulting from the transformation of microstructure. Protein subunits of 7Sα', 7Sα, 7Sβ, 11SA3, 11S acidic, and 11S basic proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, band intensity of protein subunits declined at storage and cooking phase, indicating that crosslinking of proteins was still in progress. In conclusion, the addition of TGase improved the quality of CaCl₂-induced WSC and could be used to facilitate the production of this new type of soybean product.