The effect of germination on the phytase activity, phytate and total phosphorus contents of some Nigerian-grown grain legumes

Abstract

Grain legumes are under-exploited as possible sources of phytase for the poultry industry. The current study was conducted to assess the effect of germination on phytase activities, phytate and total phosphorus content in samples of Nigerian-grown grain legumes. The legumes screened were African yambean (AYB, Sphenostylis stenocarpa), lima bean (Phaseolus lunatus), pigeon pea (Cajanus cajan), cowpea (Vigna unguiculata) and groundnut (Arachis hypogea). Phytase activity was low in AYB, lima bean and pigeon pea but high in cowpea and groundnut. Phytate content ranged between 3.01 g kg(-1) and 8.95 g kg(-1) while total phosphorus content ranged between 2.63 g kg(-1) and 5.93 g kg(-1). The grain legumes with higher phytase activity recorded the lowest phytate and phosphorus content. During germination there was an initial 4-fold to 35-fold increase in phytase activity after 6-7 days of germination followed by a decrease until 10 days (P < 0.05). The increase in phytase activity during germination was accompanied by a significant reduction in phytate (P < 0.05) and a small but significant increase in total phosphorus. The increase in phytase activity and the accompanying decrease in phytate content could have a positive implication for the nutrition of poultry and ruminants and for the environment.