Effect of dehulling and boiling on the physico-chemical, functional and pasting properties of two varieties of Mucuna bean (Mucuna pruriens L.) flours

Abstract

This study aimed to evaluate the effects of dehulling and boiling on the physico-chemical, functional and pasting properties of two varieties of Mucuna bean flours. Dried beans sample was soaked in distilled water and divided into two sets from which one was manually dehulled. The dehulled and undehulled beans were boiled followed by drying and milling into flours. A third set of flour was obtained by direct milling of whole dry beans. The results revealed that the proximate composition changed significantly (p < 0.05) with boiling and dehulling while variety generally had little effects. Protein (range 25.6–31.2 %), total sugar (range 46.5–51.1 %) and lipid (range 1.5–7.2 %) levels increased significantly (p < 0.05) with dehulling, and decreased with boiling. In reverse the ash (range 1.7–4.6 %), polyphenols (range 0.82–5.32 %), phytates (0.83–1.64 %) and l-Dopa (range 94.03–611.12 mg/100 g) contents decreased with dehulling and boiling. The particle size of flour was also shown to increase with boiling and decrease with dehulling. The combined changes in physical and chemical properties induced significant modification in the functional and pasting properties of the flour as attested by the highly significant (p < 0.01) correlations observed. In this respect protein and total sugar levels in the flour were positively correlated with the water absorption capacity, water solubility index, foaming capacity and foaming stability. The pasting viscosity was positively correlated with the phytic acid and l-Dopa levels in the flour.