Inositol phosphate degradation by the action of phytase enzyme in legume seeds

The kinetics of inositol phosphate degradation during the action of naturally occurring endogenous phytase for up to 90 min in pea and lentil flours has been studied, and compared with the addition of commercial phytase enzyme. In raw lentils IP₆, IP₅, IP₄ and IP₃ were present, whilst in peas only the presence of IP₆ and IP₅ was observed. Endogenous phytases were activated when legume flour was suspended in acidified water at pH 5.5 and 37 °C, and significant differences between lentils and peas were found. IP₆ suffered a sharp reduction in lentils and peas (81–91 and 73–93%, respectively), this reduction being slightly more pronounced after the addition of commercial phytase. The content of IP₅ decreased in lentils (48–69%), and increased in peas, except when commercial phytase acted for the first 30 min, after which a reduction was found (23%). The content of IP₄ generally decreased in lentils, except when endogenous phytase acted for 30 min when an increase was observed. However, in peas, IP₄ appeared in high concentrations up to 60 min by the action of both endogenous and exogenous phytases. The content of IP₃, on the other hand, did not change greatly in lentils. In peas it was not detected after the action of endogenous phytase enzyme and it appeared in a large amount after the action of commercial phytase. In order to obtain legume flour with low IP₆ and IP₅ contents and notable IP₄ and IP₃ contents, the action of naturally endogenous phytase for 30 min in lentils is recommendable, as well as the addition of commercial phytase enzyme for 60 min in peas.