Effects of ascorbic acid and ferrous sulfate on trace element extractability by dialyzation of weaning foods

Response surface methodology was used to study the effects of pea and soybean, and the effects of fortifying weaning foods with ascorbic acid and ferrous sulfate, on the dialyzabilities of copper, zinc and iron. Of the three elements, only zinc was insensitive to all four factors. The marked influence of pH on dialyzed iron is related to the ability of certain ingredients to alkalinize (soybean) or acidify (ascorbic acid) food. Under the conditions tested, using ready-to-eat foods, the negative effect of soybean on trace element dialyzability was significant only in the case of iron. Although ascorbic acid had a positive effect on iron dialyzability, it also had a strong negative effect on that of copper. Fortification using ferrous sulfate elicited a similar positive effect on dialyzabilities of both copper and iron. (C) 2003 Elsevier Ltd. All rights reserved.