**3.2 Dehulling**

Dehulling is a procedure through which seed coats or testa are removed either mechanically or using a machine. In most traditional setting, the process is carried out using either mortar and pestle or grinding stone, depending on the available option. Dehulled seeds have a good appearance in texture, cooking quality, palatability, and ease in digestibility. The approach reduces cooking time in grains legumes because during the dehulling process impermeable seed coats which usually prevent water uptake are removed [120]. Dehulled AYB grains showed the shortest cooking time of 35 minutes as against 80 and 150 minutes reported for whole seeds and soaked seeds, respectively [121]. The dehulling approach was observed to have a significant effect on the functional properties of AYB flour; a higher bulk density (0.93 g/cm3 ) was reported as against the bulk density (0.59 g/ cm3 ) in cowpea and pigeon pea (0.70 g/cm3 ). Similarly, the swelling index (5.9 g/ cm3 ) of dehulled AYB flour is more than the observed value in cowpea (3.7 g/cm3 ) and pigeon (4.1 g/cm3 ). The water absorption capacity (2.8 ml/h20/g) in dehulled AYB flour was also higher than the observed in cowpea (1.2 ml/h20/g) and pigeon pea (2.4 ml/h20/g) [122]. In a further experiment, a higher water capacity of 71 ml/g was observed for dehulled AYB than the value of 60 ml/g reported for raw samples [71].

About 80–90% of the total amount of potential anti-nutrient factors (polyphenols) in grain legumes are found in the seed coats, and thus dehulling has proven to be effective in reducing anti-nutrient contents especially those found in the seed coats [123, 124]. Authors reported a drastic reduction in oxalate, phytate, saponin, trypsin inhibitor, and tannin content of dehulled AYB flour [122]. Similarly, an increase in protein but a decrease in calcium and iron was reported for dehulled AYB flour [43]. In a separate study, the proximate analysis of dehulled AYB flour showed high protein content, high carbohydrate concentration, and sufficient level of amino acid [125].
