Tempe Fermentation of Whole Grain Barley Increased Human Iron Absorption and In Vitro Iron Availability

In this study, iron absorption from a tempe fermented whole-grain barley meal was measured, and results were compared to in vitro estimation of available iron from an equivalent meal. The tempe meal (TM) was prepared from barley fermented with Rhizopus oligosporus to reduce the phytate content <0.5 mol/g. Boiled barley with preserved phytate content was used as reference meal (BBM). Iron was added to obtain a total content of 3 mg meal in the human study, and to the in vitro meals 7 mg of iron was added. The iron absorption from TM and BBM was 5.5±1.5% and 3.0±0.7% respectively, and in vitro iron availability was 4.9±0.2% in TM and 1.7±0.1% in BBM (absorbed fraction of total iron/meal). To conclude, iron absorption from a barley meal was improved by reducing the phytate content via tempe fermentation, and iron absorption was predicted by direction in the in vitro experiments.