Effects of Treatment Methods on Some Properties of Bambara Nut (Voandzeia subterranean L. thouars) Flours

Abstract

The effects of some treatments of Bambara nut (Voandzeia subterranean L. Thouars) seeds on the functional and pasting properties and proximate composition of flours milled from the treated seeds were investigated. The first portion of the brown variety of the legume was soaked in cold portable water for 24 hrs, the second and third portions were soaked separately in cold portable water at room temperature for 3 hrs, followed by draining, and controlled germination on cleaned, moistened sawdust in opaque plastic trays for 48 and 72 hrs respectively. The soaked and sprouted samples were then drained and harvested seperately, followed by drying at 60^oC for 8 hrs in a locally fabricated air-dryer. The fourth portion was taken as un-treated sample. Each portion was then manually de-hulled and milled into flour of particle size < 300microns. The flours were analyzed for proximate composition and physical and rheological properties. Each flour sample was used to prepare steam bean paste gel “Moinmoin” which was then evaluated for sensory parameters. Water-soaking produced no appreciable effect on proximate composition, while sprouting produced marginal increase in protein (22.24+0.88 for sample sprouted for 48 hrs compared to 20.73+1.24 for untreated sample) and crude fibre contents but reduction in fat and carbohydrate contents compared to untreated sample. Sprouting and water-soaking resulted in reductions in most functional and pasting properties of the samples compared to untreated sample except solubility (9.58 and 13.05 for untreated and 48-hr sprouted samples respectively) and peak viscosity (9.67 and 29-72 for untreated and 24-hr sprouted samples respectively), for which untreated sample had lower values . Most “Moinmoin” sensory parameters were adversely affected by sprouting compared to water-soaked and untreated samples. There were significant differences for most sensory parameters (p < 0.01 and p < 0.05), except for taste. “Moin-moin” prepared from water-soaked sample received highest acceptability scores for the sensory parameters (p < 0.05) compared to other treated sample.