Solubility of inorganic iron as affected by proteolytic digestion.

The effects of enzymatic digestion on the iron-solubilizing properties of chicken muscle were examined. A water-soluble extract, an acid-soluble extract, and an acid-insoluble fraction were subjected to a simulated gastrointestinal digestion using pancreatin and/or pepsin: The solubility of added Fe was significantly affected only by the acid-insoluble fraction and increased linearly as pepsin digestion progressed from 0 to 4 h. A maximum was reached when this treatment was followed by a 1-h pancreatin digestion. Pepsin digestion products with molecular weight (MW) less than 10,000 solubilized significantly more Fe than those with MW greater than or equal to 10,000. In contrast pancreatin digestion products of MW less than 10,000 were not effective Fe-solubilizing agents. The influence of chicken breast muscle on added Fe solubility appears to be related to the production of digestion intermediates that can act as ligands in the formation of soluble Fe complexes.