Abstract: In this study, we evaluated the effect of synergetic induction of transglutaminase (TGase) and magnesium chloride (MgCl2) on the gel forming properties of cold-pressed soybean flour. The results showed that the dietary fiber content of tofu prepared from cold-pressed soybean flour using MgCl2 or in combination with TGase as a coagulant increased by three times, and the fat content was only one third compared to tofu prepared from tofu prepared from regular soybean flour using MgCl2 as a coagulant (control). Addition of TGase could obviously improve the internal water content of cold-pressed soybean flour gels, making the gel structure more uniform gel, and resulted in higher storage modulus G′ (10 498 Pa), indicating a stronger gel network structure, Consequently, the highest water-holding capacity (51.01%), product yield (244%) and random coil percentage (21.45%) were obtained. The disulfide bond content of tofu coagulated with TGase + MgCl2 (5.46 μmol/g) was close to that of the control sample (7.02 μmol/g). The scanning electron microscopic (SEM) results showed that the synergistic effect TGase and MgCl2 gave a more compact gel network structure, which was close to that in the control sample. Therefore, the synergetic effect of TGase and MgCl2 could improve the gelling properties of cold-pressed soybean meal proteins. The results of this study can provide a theoretical basis for diversified development of cold-pressed soybean powder.

Key words: cold pressed soybean meal; tofu gel; dietary fiber; transglutaminase; rheology; structure