Effect of Soaking and Boiling on Anti-nutritional Factors, Oligosaccharide Contents and Protein Digestibility of Newly Developed Bambara Groundnut Cultivars

Abstract

Newly developed Bambara groundnut (Vigna subterranea L.) seeds (Accessions No: TVSU 5 – Bambara Groundnut White (BGW) and TVSU 146 – Bambara Groundnut Brown (BGB)) were collected from International Institute of Tropical Agriculture (IITA), Nigeria, planted and harvested. The effects of processing methods (soaking and boiling) on anti-nutritional factors and oligosaccharides content and protein digestibility of BGW and BGB compared with Bambara groundnut commercial (BGC) seeds were investigated. Soaking and boiling significantly reduced the anti-nutritional factors of the samples and the effect increased as processing time was elongated. Sample BGC had lower anti-nutritional factors than BGW and BGB after soaking for 48 h. Tannin contents of the samples were reduced drastically by 99 % throughout the soaking periods. Greatest loss in raffinose level was observed in BGB (59%) and BGW (50%) after boiling for 60 min compared with BGC (43%). The loss in stachyose content of the samples varies with processing and BGC (59%) had greatest loss after boiling for 60 min while soaking for 48 h reduced that of BGB and BGW by 57 and 35%, respectively. Boiling for 60 min increased the in vitro protein digestibility of BGB (89.34 %) compared with BGW (87.48%) and BGC (82.89%). Overall, the results demonstrated that soaking and boiling of newly developed Bambara groundnut seeds could improve the nutritive quality of the seeds.