Evidence of a Synergistic Effect between Pea Seed and Wheat Grain Endogenous Phytase Activities

Distribution of phytic acid and phytase activity in pea seeds was analyzed and compared with those in wheat grains under identical assay conditions (55 °C, pH 5.5). Most total phytic acid content and phytase activity were found in pea cotyledons. In wheat grains, debranning resulted in a 70% reduction in phytic acid content, whereas more than 40% of the total phytase activity remained. The possibility to hydrolyze phytic acid by use of ground debranned wheat as a source of phytase in blends with pea cotyledon flour was investigated. The Michaelis-Menten parameters for each endogenous enzyme were identified and used to predict the rate of phytic acid hydrolysis. Results demonstrate a synergistic effect between the two phytase activities, enabling a 70-95% reduction of phytic acid depending on pea/wheat flour ratios in a relatively short time (4 h). This reduction appears to be able to increase zinc bioavailability but remains insufficient for iron.