Chemical Speciation of Iron in Different Varieties of Beans (Phaseolus vulgarisL.): Cooking Effects

Beans are considered a source of iron (Fe), and hence have considerable contribution in cases of Fe deficiency. Beans also contain certain anti-nutritional constituents, which are imperative to the cooking of beans. The nutritional value of beans depends on the bioavailability, which can be affected by cooking. Studies about heating effects in distribution of Fe-based inorganic species are limited, especially for bean cultivars commonly consumed in Brazil. The aim of this work was to evaluate the effects of domestic cooking on the distribution of Fe species (water soluble and inorganic) in seven varieties of Phaseolus beans. Fractionation procedures were used to separate Fe associated to various species. The Fe content was quantified by graphite furnace atomic absorption spectrometry (GF AAS). In raw beans, the inorganic Fe species significantly contributes to the water soluble fraction obtained after fractionation. Cooking lowered the concentration of water soluble Fe in majority varieties of beans.