Effect of phytase treatment on iron bioavailability in faba bean (Vicia faba L.) flour

The effect of dephytinisation, using an exogenous phytase under optimal conditions (pH 5.5, 37 °C), and subsequent removal of the soaking solution after processing, on the bioavailability of iron from faba bean (Vicia faba L.) flour was studied. Soaking of the faba bean flour led to a considerable reduction in the content of iron (39%), whereas a lower reduction in iron content (10%), was obtained after additional treatment with phytase, than in the soaked faba bean flour. The digestive utilisation of iron from the raw and soaked faba bean flours by growing rats was negligible, but increased significantly as a result of phytase treatment. The low iron absorption obtained for the former two treatments, during an experimental period of 10 days, was not reflected in any of the haematological indices (red blood count, haemoglobin, haematocrit) or tissues (femur, heart, kidney) studied, with the exception of the sternum. The latter appears to be a useful indicator of iron bioavailability.