Physicochemical properties of Bambara groundnut ( Vigna subterranea ) starch annealed at different temperatures

Abstract

Bambara groundnut is a starchy grain that could serve as a starch source for the industry. In the native form, starches are generally unsuitable for most industrial applications and hence are modified. Physical modification methods including annealing are preferred for starch modification because they are environmentally friendly. Previous studies on the annealing of Bambara starch focused on single-temperature treatment. This study investigated the physicochemical properties of Bambara starch annealed at varying temperatures of 45, 50, 55, and 60°C for 24 h. The amylose contents of the starches varied between 27.18% and 28.53%. Annealed Bambara starches showed significantly lower swelling and solubility values than the native starch. Furthermore, except for the time to peak (4.05–4.44 min), pasting temperatures (81.95–84.00°C), gelatinization temperatures (70.47–77.23°C), and gelatinization enthalpies (3.95–4.41 J/g) which increased the pasting properties of the annealed starches decreased. The result of this study should guide researchers on the specific annealing temperature to use for specific food and industrial applications. Novelty impact statement Bambara grains are rich in starch which could be used as an alternative and cheap starch source to the conventional corn and potato sources. This study report for the first time the impact of different annealing temperatures on the physicochemical properties of Bambara starch. Annealing was chosen because it is an environmentally friendly method of starch modification. Results from this study show that the modified starch would have varying applications in the food industry, for example as a thickener, and as a stabilizer.