Quality changes and mineral composition of African yam bean (sphenotilis sternocarpa) cooked in kaun (trona) solution

Some quality attributes (cooking time, water absorption and organoleptic qualities), pH, chemical and mineral composition of African yam bean (AYB) cooked in “kaun” solution have been investigated. Cooking in different concentrations of kaun at atmospheric pressure and longer cooking time generally increased water absorption but the optimal cooking conditions (i. e. best kaun concentration and minimum cooking time to achieve optimal quality) were found to be 0.1% and 90 minutes respectively. Cooking in kaun solution of concentration higher than 0.1% caused an unappealing deep brown colour, less number of splitted beans or even no splits and decreased softening of the beans. While cooking in kaun solution at the optimal conditions at atmospheric pressure increased the concentrations of Zn, Ca, Fe, Na and K in both the cooked beans and leached solids, it decreased the concentration of Mg and Cu in the cooked beans. Cooking in kaun solution was also found to produce some little changes in proximate composition. Explanations on the mechanism of softening of the beans in kaun solution were discussed.