Effect of microwave treatment on cooking time, colour, sensory and nutritional properties of Bambara groundnut (Vigna subterranea)

Abstract

Bambara groundnut is a leguminous crop that currently experiences a low level of utilisation because it is hard-to-cook and difficulty to dehull. In this study, the effects of different microwaving power of 450, 500, 600 and 750 W and time (0, 30, 60, 120 and 240 s) on cooking time, colour, sensory and nutritional properties of Bambara groundnut using standard methods were investigated. Microwaving generally reduced the cooking time of Bambara groundnut. The cooking time reduced by approximately 28, 46, 52 and 55% when Bambara groundnut was microwaved at 450, 500, 600 and 750 W for 240 s, respectively. Microwaving did not significantly (p>0.05) affect the colour and appearance of the grain. Bambara groundnut had similar lightness values (60.66-63.15), but slightly different a (3.38-5.57) and b values (16.16-19.20) after microwaving. Protein (23.90-26.88%) and carbohydrate (47.85-58.58%) were the major components of raw and microwaved grains. Microwaved grains showed higher digestibility values (approx. 78-85%) compared to the raw Bambara groundnut (approx. 71%). Mean sensory scores revealed that Bambara groundnut microwaved at 600 W for 240 s had comparable acceptability with the control sample. Microwaving can be used to reduce cooking time of Bambara groundnut, improve protein content and digestibility without significantly altering the sensory properties.