The Effects of Processing on the Proximate and Phytochemical Compositions of Mucuna pruriens Seeds (Velvet Beans)

Abstract

The effects of processing on the proximate and phytochemical compositions of Mucuna pruriens seed extract were investigated. The proximate analysis of the hulled seeds revealed the following nutrients and antinutrients: Crude lipid (2.69%), crude fiber (3.86%), crude protein (28.23%), ash (5.26%), carbohydrate (60.03%) and moisture content (12.32%). The boiled or cooked samples exhibited the following results: Crude lipid (2.51%), crude fiber (3.83%), protein (22.17%), ash (4.24%), carbohydrate (67.92%) and moisture content (12.32%). After soaking prior to boiling or cooking at 98^oC for one hour, the results were: Crude lipid (2.51%), crude fiber (3.81%), protein (22.05%), ash (3.10%), carbohydrate (68.52%) and moisture content (11.92%). Quantitative phytochemical analysis of the raw seed extract indicated: Flavonoids (0.42%), alkaloids (1.07%), saponins (0.47%), tannins (0.28%), hydrogen cyanide (12.69 mg/kg), phenol (2.82%) and phytate (0.43%). The concentrations of the phytochemicals in the boiled samples were as follows: Flavonoids (0.35%), alkaloids (0.88%), saponins (0.39%), tannins (0.09%), hydrogen cyanide (6.59 mg/kg), phenols (0.33%) and phytate (0.24%). The soaked and boiled samples showed the following result: Flavonoids (0.31%), alkaloids (0.88%), saponins (0.37%), tannins (0.08%), hydrogen cyanide (5.54 mg/kg), phenols (0.32%) and phytate (0.22%). The effects of processing involving soaking, soaking and boiling, have remarkable detoxification effect, anti-nutrient and nutrient composition reduction on Mucuna pruriens seeds. The most highly affected anti-nutrient and toxicant in the seed is hydrogen cyanide, which showed a reduction from 12.67 mg/kg for the raw sample to 5.54 mg/kg for the soaked and boiled samples; a reduction of 56.34%. Another anti-nutrient, phytate was reduced by more than 48.84%; phenols from 2.83% to 0.32%, a reduction of 88.69%; we therefore conclude that the effects of processing vis a vis the methods employed, have significant effects in the reduction of the concentrations of the anti-nutrients and toxicants present in the seeds of this under-utilized legume. We recommend that these novel processes be employed by individuals, farmers and food processing companies wishing to include this all important legume as part of family dietary as well as in poultry, animal feeds or in the formulation of diets for the undernourished and low income groups.