Iron and zinc bioavailability in common bean (Phaseolus vulgaris) is dependent on chemical composition and cooking method

The influence of genotype and domestic processing on iron and zinc bioavailability in common bean germplasm was investigated using an in vitro digestion model. Raw beans exhibited diversity in iron content (50 to > 90 mg kg(-1)) although zinc content was similar (30-40 mg kg(-1)). Following preparation by different household cooking methods < 5% of the iron in raw beans was recovered in the bioavailable fraction following in vitro digestion. However, up to 20% of zinc present in dry seeds was bioavailable. A high proportion of iron and zinc in raw beans (up to 40%) was lost by leaching into cooking water when beans were prepared by boiling. Although untargeted LC/MS revealed genotype-dependent differences in grain chemistry, correlations between mineral bioavailability and antinutritional phytates and polyphenols were mostly insignificant. Our data highlight the need to consider losses during domestic processing and the related physicochemical traits in biofortification programmes.