Evaluation of phytochemical constituents, proximate contents and glycemic index of bambara groundnut (Vigna subterranea L. Verdc) varieties grown in Northeastern Nigeria

Abstract

Bambara groundnut (Vigna subterranea L. Verdc) is widely used as a source of food and also has rich fibre and nutritional values. Hence, this research aimed at determining the phytochemical, proximate content as well as glycemic index and glycemic load of four varieties of Bambara groundnut found in Alkalere area of Bauchi State northeastern Nigeria for possible nutritional and medicinal utilization. Seeds of Bambara groundnut varieties were processed by heating at 60°C and cooled then grinded into powder using a mechanical grinder. The flour was used for phytochemical and proximate analysis as well as glycemic index (GI) and glycemic load (GL) determinations. The results revealed the presence of saponins, tannins, steroids, cardiac glycosides, alkaloids and flavonoids in all the varieties while anthraquinones was not detected in all the four varieties. Proximate analysis showed high contents of carbohydrates and protein with low ash content in all the four varieties. The study also found that black seeds of Bambara groundnut had the lowest GI of 66.1 and GL at 1.33 while Brown-black seeds Bambara groundnut was the highest values in GI 75.6 and GL 1.51, respectively. The study for the first time reported the GI and GL differed among varieties with different seed color of different varieties of Bambara groundnut where a black seed variety of Bambara groundnuts possessed some good qualities for use in the nutritional management of blood glucose likely for diabetic patients.   Key words:  Bambara groundnut, phytochemical properties, proximate, glycemic index, glycemic load.