Effects of phytase and polyphenol oxidase treatments onin vitroiron bioavailability in faba bean (Vicia faba L.)

After reduction of phytate with phytase, water slurries of faba bean flour were incubated with polyphenol oxidase (mushroom tyrosinase), and the effects on different phenolic groups and on in vitro iron bioavailability were studied. Enzyme incubation was also performed after cooking, soaking and germination of the faba beans. Phytase incubation significantly decreased the phytate content, and incubation with polyphenol oxidase had a reducing effect on total phenol content, as well as on the amount of catechol and resorcinol groups. The in vitro iron bioavailability increased when the faba beans were incubated with phytase and polyphenol oxidase, and the highest in vitro iron bioavailability was obtained when the soaked samples were incubated. The results from this study suggest that oxidation of polyphenols in the faba bean, after reduction of phytate, may be used to increase the bioavailability of iron in foods prepared from this legume.