Comparative Phytochemical Analysis of Bambara Groundnut (Vigna subterranea) and others Vigna spp. with Respect to its Nutritional, Antinutritional and Antioxidant Properties

Abstract

Aims: Bambara groundnut is considered as underutilize and commercially forgotten legume in Malaysia. Few studies abroad showed interesting potential on its phytochemical and nutritional contents. This study was carried out to investigate and compare the nutritional, antinutritional, free radical scavenging assay, total phenolic content and fatty acids composition of Bambara groundnut (Vigna subterranea) with comparison with two others commercial legumes (Vigna spp.) red bean (V. angularis) and black-eyed pea (V. unguiculata) in Malaysia. Study Design: Each sample was extracted three times (n=3) for the free radical scavenging assay, total phenolic content, fatty acids composition and antinutritional content. All the data were analysed using ANOVA and Tukey Pairwise tests. Place and Duration of Study: Phytochemistry Laboratory, Kompleks MyGene Bank, Malaysian Agricultural Research and Development Institute (MARDI), Serdang, Selangor, Malaysia from April to December 2022. Methodology: Bambara groundnut (BGN), red bean (RB) and black-eyed pea (BEP) were purchased from various local market situated in the northern state of Peninsular Malaysia. Each sample was dried in the oven at 40°C for 3 days. Samples were grounded and its proximate and minerals content were determined. Each sample was extracted for the free radical scavenging assay, total phenolic content, oxalates (total, soluble and insoluble) content using HPLC and fatty acids composition using GCMS. Results: Bambara groundnut (BGN) was found to have higher total carbohydrate content (66.0 ± 0.01 g/100g) compared with RB and BEP (P<0.05) hence provides more energy (406.67 ± 1.25 kcal/100g) (14% higher than red bean and black-eyed peas). Further analysis on its mineral content revealed the legume is rich in potassium (24% higher than red bean and black-eyed peas) suggesting its potential to regulate body fluid and muscle contractions. The bambara groundnut’s seed oil is rich in fatty acids; omega 3 and 6 (palmitic acid, α-linoleic acid and linolenic acid). BGN also have higher phenolic content (87.3 ± 2.05 g/100g) compared to RB and BEP (P<0.05). The free radical scavenging assay showed moderate antioxidant activity with inhibition concentration (IC50) value of 0.57 ± 0.04 mg/ml (standard: ascorbic acid = 0.06 mg/ml). The underutilize legume also had undetectable oxalate content; hence it is safe for human consumption (lethal dose 660 mg/kg body weight). Conclusion: The potential findings on this legume should elevate the importance of this crop to be commercialised locally and for the future crop that will lead to achieve food security particularly in Malaysia.