Physicochemical properties and consumer acceptability of Bambara groundnut tofu chunks

Abstract

Bambara groundnut (BGN) (Vigna subterranea [L.] Verdc.) is a protein-rich legume suitable for developing healthy, high-quality meat alternatives for vegetarians and health-conscious consumers. This study evaluated the physicochemical and sensory properties of tofu chunks derived from BGN tofu. A response surface I-optimal point exchange randomised design was used to determine the effect of gum Arabic (0.3, 0.4, 0.5 %) and sodium alginate (0.3, 0.4, 0.5 %) on the textural, physicochemical and rheological properties of BGN tofu. The design consisted of six models, with three lack of fit and three replicate points, giving a total of twelve runs. The interaction of gum Arabic and sodium alginate was optimal at 0.5 % and was further used to make tofu chunks. Incorporating gum Arabic and sodium alginate significantly (p < 0.05) enhanced the colour characteristics and protein content of the chunks. Bambara groundnut tofu chunks were a good source of essential amino acids, with leucine (4.34–4.94 %) and phenylalanine (4.61–5.62 %) being the most abundant. Samples with 0.6 % gluconolactone (GDL) had higher lysine (3.76 %) and alanine (2.65 %) content than others. Chunks prepared with vinegar + 0.5 % gum Arabic + 0.5 % sodium alginate had the highest protein content (53.09 %), while those with 0.6 % GDL had the lowest (42.70 %). Tofu chunks made with 0.6 % GDL had the highest carbohydrate content (43.10–47.38 %) and significantly (p < 0.05) increased bulk density, particularly in ground samples. Chunks formulated with 0.6 % GDL, gum Arabic, and sodium alginate received the highest sensory evaluation scores for appearance, colour, taste, texture and overall acceptability. Bambara groundnut tofu chunks are a promising candidate for novel, sustainable, legume-based meat analogues, with functional ingredient selection offering opportunities to optimise product quality and consumer appeal.