Impact of Deep Ocean Water on the Textural and Microstructural Properties of Soybean-Based and Winged Bean-Based Tofu

The coagulation behavior induced by deep ocean water (DOW) was critical in determining the textural and microstructural properties of tofu derived from soybean and winged bean proteins. In this study, soybean milk and winged bean milk were subjected to thermal denaturation, followed by the addition of 2.0% DOW as a coagulant to facilitate tofu formation. Textural profile analyses and penetration tests revealed distinct differences between the two tofu varieties. Winged bean-based tofu exhibited a hardness of 1476.4 ± 89.2 g, springiness of 3.09 ± 0.20, breaking strength of 25.0 ± 2.9 N/m², and deformation of 4.49 ± 1.29 mm. In comparison, soybean-based tofu demonstrated higher hardness (2195.9 ± 86.5 g), lower springiness (0.99 ± 0.20), greater breaking strength (45.6 ± 2.5 N/m²), and increased deformation (7.78 ± 2.55 mm). Scanning electron microscopy revealed a honeycomb-like microstructure in both tofu types; however, winged bean-based tofu exhibited larger and more uniform pores, whereas soybean-based tofu displayed an internal structure characterized by coagulated flocculent networks. These findings highlight the potential of winged beans as an alternative plant-based protein source for gel formation and underscore the novel role of DOW as a coagulant in modulating the structural properties of tofu during production.