Novel insights into the effect of magnesium chloride or combined with glucono-δ-lactone on the quality of tofu

Tofu, a globally significant plant-based protein source, is traditionally produced using a variety of coagulants, including salts, acids, or enzymes, each of which influences its texture, yield, and nutritional quality. Understanding the role of these coagulants is crucial for optimizing tofu production and enhancing its commercial appeal. This study aimed to investigate the effects of magnesium chloride (MgCl₂), glucono-δ-lactone (GDL), and their combination (GDL+MgCl₂) on the physicochemical properties and digestibility of tofu. Results indicated that tofu made with GDL showed the highest yield (700.0 ± 10.0 g) but the lowest water retention (41.0 ± 7.5%) and the highest cooking loss (32.0 ± 3.0%). In contrast, tofu produced with MgCl₂ exhibited superior water holding capacity (92.2 ± 4.6%) and lower cooking loss (3.4 ± 0.2%). The combination of GDL and MgCl₂ synergistically improved water retention and reduced cooking loss to 1.5 ± 0.2%. Electrophoresis analysis revealed that the combined coagulant enhanced protein retention in tofu. During digestion, GDL + MgCl₂ tofu showed higher soluble protein and peptide content than tofu prepared with single coagulants, suggesting improved protein breakdown and bioavailability. These findings underscore the significance of coagulant selection in optimizing tofu quality and suggest that composite coagulants can improve physicochemical characteristics and protein digestibility. Future research should consider in vivo studies to validate these findings, further optimize coagulant concentrations, and explore the long-term health benefits of tofu made with composite coagulants. This study provides a theoretical basis for improving tofu quality and advancing the tofu production industry through composite coagulant application.