Microwave Pretreatment of Presoaked Bambara Groundnut Seeds Enhances the Functionality and Phenolics-Related Antioxidant Properties of the Resultant Flour

Abstract

This study investigated the effect of microwave pretreatment on cooking time of presoaked Bambara groundnut seeds, functional properties of resultant flours, and their phenolic composition and antioxidant properties. Microwave treatment significantly decreased cooking time and resulted in decreased water solubility index (WSI) (by up to 66%) and nitrogen solubility index (NSI) (up to 81%) of the resultant flours, as well as a decrease in pasting viscosity and enthalpy compared to raw flour. However, the 1200 W treatment resulted in higher pasting viscosity, WSI, and NSI than the 900 W treatment. There were differences in type of flavonoids and phenolic acids between the two types of Bambara groundnut seeds, while microwave treatment caused certain increase and decrease in individual flavonoids, such as catechin, quercetin-3-O-glucoside, and hesperidin. The flours maintained good radical scavenging antioxidant activity and protected plasmid DNA from oxidative damage. Overall, the study suggests that microwave pretreatment shows potential in alleviating the hard-to-cook Bambara groundnut seeds in producing flour with functional and antioxidant properties.