Impact of processing on Fe dialysability from bean (Phaseolus vulgaris L.)

The influence of dehulling and cooking on in-vitro Fe dialysability from two varieties of Phaseolus vulgaris L. (mottled and white beans) was investigated. Fe and seed constituents (phytate, tannin, dietary fibre) were differently distributed between hull and cotyledon. Fe dialysability from mottled bean was 2.5%, from white bean 3.6%. Dehulling significantly decreased Fe dialysability (36%, P < 0.025) from both varieties. Cooking significantly reduced Fe dialysability from mottled bean (59%, P < 0.025), whereas in white bean no modifications were detected. On the other hand, cooking positively influenced Fe dialysability from cotyledon: compared with the raw samples, both varieties showed a significant increase (54%, P < 0.025) in Fe dialysability. This study showed that localization of both Fe and some seed constituents in seed affected Fe dialysability. Changes in food constituents (i.e. degree of protein digestion) account for the modifications in Fe dialysability subsequent to cooking.