Characterisation of Pretreated African Yam Bean and Bambara Groundnut Seed Coats for Possible Use in Food Formulations

Abstract

The study focused on characterising pretreated African yam bean (AYB) and Bambara groundnut (BGN) seed coats for possible use in food formulations. The AYB and BG seed coats were dehulled to separate the seed coats from the cotyledon. The seed coats were pretreated using warm water, sodium bicarbonate solution, wild fermentation. The untreated served as control. The pre-treated seed coats were dried and milled to obtain their flours. The different flour samples were subjected to phytochemical, antinutrient, antioxidant and dietary fibre analyses using standard methods. The phytochemical result of the BG seed coat showed that phenol content ranged from 3.58 to 7.04 mgGAE/g and flavonoid ranged from 0.04 to 0.15 mgRUT/g, respectively. The phenol and flavonoid contents of AYB ranged from 3.68 to 17.07 mgGAE/g and 0.06 to 0.43 mgRUT/g, respectively. The antioxidant activities of the seed coats were obtained as FRAP (4.01-7.48; 5.88-23.70 mg/g), DPPH (21.16-86.35; 13.13-90.43%) and ABTS (0.01-0.03; 0.02 to 0.03 Mmol/g) for BG and AYB seed coats, respectively. The dietary fibre results showed that the BG seed coat had insoluble and soluble fibres of 26.70-49.91 and 17.40-18.28% when compared to 38.23-59.13 and 14.44-16.26% for the AYB seed coat, respectively. Besides, the phytate (4.53-6.18 mg/100g), oxalate (0.09-0.23 mg/g) and trypsin inhibitor (13.87-20.79%) contents of BG were significantly (p<0.05) similar to 2.06-6.59 mg/100g; 0.18-0.41 mg/100g and 18.96-27.45% obtained for AYB, respectively. The findings concluded that pretreatment methods had varying effects on the phytonutrients and anti-nutrient compositions of AYB and BG seed coats and that the seed coats of these legumes could be an essential raw material in functional food formulations.