Physicochemical, Structural, and Nutritional Properties of Termite Mushroom-Fortified Tofu and Its Antioxidant Activity During In Vitro Digestion

Termitomyces albuminosus is a wild edible mushroom with potential as a functional ingredient, yet its effect on tofu quality remains unclear. This study evaluated soy tofu fortified with Termitomyces albuminosus freeze-dried mushroom powder (TMP) at 1.5, 3, and 5% (w/w) using two strategies: direct addition and soybean replacement. The tofu treatments were assessed for yield, colour, texture, microstructure, molecular interactions, rheological behaviour, proximate composition, mineral profile, and antioxidant activity in fresh, cooked, and in vitro digested states. Increasing TMP progressively reduced yield, lightness, hardness, cohesiveness, and chewiness, with greater deterioration under high percentage replacement, associated with dose-dependent protein network coarsening and protein–polysaccharide phase separation; nevertheless, all samples retained viscoelastic gel behaviour (G′ > G″). The 1.5% replacement treatment largely preserved gel structure and texture, suggesting a favourable balance between enrichment and structural quality. The 5% replacement (R5) provided the greatest nutritional gain, significantly increasing calcium (2177.80 vs. 1812.43 mg/kg) and iron (27.07 vs. 20.61 mg/kg) compared to control while maintaining crude protein above 47% (dry basis). Antioxidant activity increased with TMP level and was highest in R5, with bioaccessibility peaking in the intestinal phase. TMP fortification represents a promising strategy for developing nutritionally enhanced tofu with improved mineral composition and antioxidant bioaccessibility.