Effect of hydrocolloids on the textural, physicochemical and rheological properties of Bambara groundnut tofu

Abstract

Bambara groundnut (BGN) is a protein-rich legume with potential for plant-based tofu production. This study explored the effects of coagulants (vinegar, lemon juice, and gluconolactone [GDL]) and hydrocolloids (gum Arabic and sodium alginate at 0.3 %, 0.4 % and 0.5 %) on the quality of BGN tofu. Factorial design and response surface methodology identified the optimal formulation as 0.5 % gum Arabic and 0.5 % sodium alginate. Vinegar-tofu and GDL-tofu were lighter, firmer and more elastic, with vinegar-tofu exhibiting a smoother texture. Tofu containing hydrocolloids exhibited higher protein, ash, and carbohydrate content, and lower moisture. Microstructural analysis revealed uniform networks in vinegar-tofu and coarser textures in GDL-based samples. Rheological analysis showed shear-thickening behaviour, with the Power law model fitting the data adequately. Coagulant type and hydrocolloid addition significantly influenced texture, microstructure and physicochemical properties. These findings provide foundational data for future optimisation of BGN-based products and the role of hydrocolloids in improving tofu quality.