Impact of a Mg2+ emulsion coagulant on tofu's gel characteristics

Abstract

In the industrial production of tofu, controlling the coagulation rate is crucial. A controlled-release Mg2+-loaded water-in-oil emulsion coagulant was employed in tofu manufacturing, and its effects on the physical properties and gel behavior of tofu were studied. Compared with MgCl2, the emulsion coagulant could extend the initial coagulation time of soybean protein from 3 s to about 30 s due to its sustained release effect on Mg2+, which significantly decelerated the tofu gelation rate. In addition, different Mg2+ release rates significantly influenced the physical properties of the final tofu gel. At an appropriate Mg2+ release rate (at 7000 r min−1), it promoted the formation of a uniform and denser gel network, increased protein β-sheet structures, and benefited tofu in terms of moisture retention, yield, color, springiness, and appearance quality improvement. However, under low Mg2+ release rate, the emulsion coagulant weakened the disulfide bond and hydrophobic action, resulting in a weaker network. It also enhanced the moisture mobility in the tofu gel, with a dehydration rate of up to 17.72%. Similarly, too fast Mg2+ release rate also resulted in uneven networks with voids, leading to reduced moisture retention, yield, and color quality of tofu. These findings aim to provide a theoretical basis for the industrial production of tofu.