Quality characteristics and antioxidant activity of low-molecular-weight fish collagen-added tofu, a soybean curd

This study investigated the antioxidant activity (2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) [ABTS], 1,1-diphenyl-2-picrylhydrazyl [DPPH]) as well as the general and quality characteristics of tofu (traditional oriental soybean curd) supplemented with low molecular fish collagen (LMFC). The yield of tofu supplemented with 0% (Control), 10%, and 20% collagen decreased significantly to 164.79%, 147.70%, and 140.49%, respectively (p < 0.05). Antioxidant activity was assessed using ABTS and DPPH, showing a significant increase (p < 0.05). The pH values were 6.37, 6.32, and 6.33, with a significant decrease at 10% supplementation (p < 0.05), while there was no significant difference between 10% and 20% (p > 0.05). Crude protein content was 10.77%, 10.78%, and 11.38%, with no significant difference between control and 10% (p > 0.05) but a significant increase at 20%. Crude ash content was 1.60%, 1.37%, and 1.44%, with no significant difference between 10% and 20% (p > 0.05), but a significant decrease compared to the control. Texture hardness and chewiness decreased significantly (p < 0.05), while elasticity showed no significant difference (p > 0.05). In Hunter color analysis, the L value (brightness) decreased significantly (p < 0.05). The b value (yellowness) and ΔE (overall color change) increased significantly (p < 0.05), but the a value (redness) showed no significant (p > 0.05) difference. This study suggests that tofu supplemented with LMFC exhibited significant differences in antioxidant activity and general characteristics, indicating potential for commercial development.