Proximate and Physiochemical Analysis of Modified Bambara Groundnut (Vigna Subterranea) Starch

Abstract

Bambara groundnut (Vigna subterranea L. Verdc.) is an underutilized, drought-tolerant leguminous crop rich in carbohydrates, offering a sustainable source of industrial starch. However, native starches exhibit functional limitations such as low thermal and shear stability, restricting their direct industrial utility. This study investigated the chemical composition, physical modification, and resulting physicochemical and functional properties of Bambara groundnut starch. Starch was isolated from clean seeds and physically modified via annealing (BAS), pregelatinization (BPS), and heat-moisture treatment at 20%, 25%, and 30% moisture contents (BHS-20, BHS-25, BHS-30). Proximate analysis of the native starch revealed a moisture content of 13.65%, ash content of 0.45%, crude fat of 1.78%, crude protein of 2.22%, crude fibre of 0.50%, and carbohydrate content of 81.90%, demonstrating high starch purity. Physicochemical characterization across temperatures (55–95°C) indicated that swelling power and solubility were temperature-dependent for all samples. Native starch (BNS) exhibited the highest swelling capacity overall (433% at 95°C), while among modified starches, BAS demonstrated superior swelling (268% at 95°C) due to enhanced structural stability. Conversely, BPS achieved the highest solubility (550% at 85°C) owing to thermal granule pre-disruption. Heat-moisture treatment restricted swelling power while increasing oil and water absorption capacities (up to 218% and 320%, respectively, in BHS-30) through internal crystalline reordering. The least gelation concentration increased progressively from BNS (8% w/v) to BHS-30 (18% w/v), reflecting strengthened intragranular binding forces. The results demonstrate that physical modification significantly alters and improves the functional profile of Bambara groundnut starch, rendering it a viable, high-performance biopolymer for food formulation, pharmaceutical excipients, and textile sizing applications.