Relationship between in vitro Fe and Zn dialysability and peptide composition of albumin and globulins extracted from cooked bean (Phaseolus vulgaris L.).

In vitro dialysability of iron, zinc and protein was determined from whole bean (Phaseolus vulgaris), albumin and globulin (G1, G2) after cooking. Albumin showed the highest iron, zinc, protein and phytic acid content. Cooking increased iron and protein dialysability only in whole bean and albumin. Compared to globulins, albumin also presented a higher in vitro protein digestibility and cystine chemical reactivity. HPLC analysis of peptides in dialysates of bean and protein fractions suggested that some aggregation occurred during dialysis. The percentage of amino acids in dialysed peptides was found to be different between albumin and globulins. The difference in iron and zinc dialysability between albumin and globulins seems to depend on the phytic acid content of the albumin fraction and the protein properties of globulins.