INFLUENCE OF THE METHOD OF PROTEIN EXTRACTION ON THE IN-VITRO EVALUATION OF MINERAL DIALYZABILITY FROM LEGUMES

The aim of this study was to investigate to what extent the in vitro e valuation of iron, zinc and protein dialysability from legumes is infl uenced by the method of globulins extraction (G1, G2). According to cl assical methods, globulins were first extracted into salt solutions co ntaining ascorbic acid. Because of the enhancing effect of ascorbic ac id on iron availability, globulins extraction was also carried out in the absence of ascorbic acid. In the presence of ascorbic acid, a para llel reduction in total protein content and in iron and zinc content w as detected, suggesting an interaction between minerals and protein co mponents. Ascorbic acid markedly improved protein dialysability and G2 always showed a higher dialysability than G1. In the absence of ascor bic acid, iron dialysability was 3.0% from G1 and 5.5% from G2, while ascorbic acid caused up to a three-fold increase in iron dialysability . Ascorbic acid did not influence zinc dialysability (20% for G1 and 2 4% for G2). For both globulins, the higher the iron/protein ratio the higher the iron dialysabLlity, indicating that the extent of interacti on between iron and protein, as well as influencing protein digestion, likely affects in-vitro iron availability.