In-vitro Antioxidant Capacity, Phytochemical Characterisation, Toxic and Functional Properties of African Yam Bean (Sphenostylis stenocarpa) Seed-Enriched Cassava (Manihot esculenta) Product (Pupuru)
Folayemi Janet Isaac-Bamgboye *
Department of Food Science and Technology, Federal University of Technology, P.M.B. 747, Akure, Nigeria.
Victor Ndigwe Enujiugha
Department of Food Science and Technology, Federal University of Technology, P.M.B. 747, Akure, Nigeria.
Matthew Olusola Oluwamukomi
Department of Food Science and Technology, Federal University of Technology, P.M.B. 747, Akure, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: This study aimed at determining the In-vitro antioxidant capacity, characterise phytochemical constituents, assess toxic and functional properties of African yam bean (Sphenostylis stenocarpa) seed-enriched Cassava product (Pupuru) flour blends using standard methods.
Methodology: Pupuru flour blends were produced from spontaneously-fermented cassava tubers substituted with African yam bean (Sphenostylis stenocarpa) seed (AYBS) (5% (EP5), 10% (EP10) and 15% (EP15), before toasting, cooling, milling, sieving and packaging. A commercial sample (CP) with 100% cassava and another produced in this study, were used as controls.
Results: In-vitro 2,2-Azino-bis (3-ethylbenthiazoline-6-sulphonic acid) (ABTS) and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging abilities, total flavonoid content (TFC), ferric reducing antioxidant power (FRAP) and total phenol content (TPC) increased significantly (P = .05) as AYBS enrichment levels increased. The commercial and laboratory control samples showed no significant difference (P = .05) in all the antioxidants analysed except DPPH: ABTS (7.61- 12.27%); DPPH (26.34-48.26%); TFC (0.10-0.25 mg CAE/g); FRAP (0.81-2.36 (mg/g) and TPC (15.74- 24.15 mg GAE/g). All the phytochemicals except tannins increased significantly (P = .05) as levels of enrichment with AYBS increased. Tannins, phytates, saponins, alkaloids and oxalates were 1.46 -2.87 (mg/g); 0.85-1.40 mg/100 g; 4.18-13.27 mg/g; 24.89-29.05 mg/g and 1.71-3.23 mg/g, respectively. The toxic constituent revealed that all the samples contained significantly different (P = .05) cyanide ranging from 0.87-2.51 mg/kg which reduced as AYBS level of inclusion increased. The functional properties of the samples were significantly (P = .05) enhanced with AYBS enrichment.
Conclusion: Utilisation of AYBS to enrich Pupuru increased its In-vitro antioxidant capacity and phytochemical constituents, reduced the toxic cyanide content enhanced the functional properties, hence, its suitability as a nutraceutical to delay the ageing process and prevent cardiovascular diseases.
Keywords: African yam bean (Sphenostylis stenocarpa) seeds, cassava, antioxidant, cyanide, phytochemicals, functional properties, nutraceuticals