Iron solubilisation by chicken muscle protein digests

Abstract

The objective of this work was to compare the solubilisation of iron by in vitro digests of soluble and insoluble protein fractions from chicken muscle. Chicken breast muscle was extracted to provide dilute salt-soluble protein (DSSP) and dilute salt-insoluble protein (DSIP) fractions. These fractions together with casein and ovalbumin were subjected to in vitro digestion in the presence of ferric iron. After proteolytic digestion, soluble iron increased fourfold for DSSP, 20-fold for DSIP, twofold for casein and 0.5-fold for ovalbumin. 64% of the soluble iron in the DSSP digest and 30% of the soluble iron in the DSIP digest were ferrous; in the casein and ovalbumin digests, less than 6% was ferrous. Dialysable iron was less than 5% of the soluble iron for all proteins and was mostly ferric iron. DSIP solubilised twice as much iron as DSSP but much less than casein or ovalbumin digests. It was concluded that muscle proteins solubilise iron by reduction and chelation to mostly large (non-dialysable) peptides resulting from digestion.