Lyophilization decreases the formation of dialyzable iron by extraction and digestion of chicken breast muscle.

摘要

Effect of lyophilisation (freeze drying) of chicken breast on the formation of dialysable Fe from ferric Fe was investigated. Chilled, frozen or lyophilised chicken breast was analysed for sulfhydryl and histidine content, before being homogenized and mixed with ferric Fe. The mixture was extracted with acid or digested with pepsin and pancreatin, and the extracts and digests were analysed for dialysable ferrous Fe, dialysable total Fe and for protein. In the chilled chicken breast, similar amounts of dialysable Fe were formed after acid extraction and after proteolytic digestion; however, digestion led to more dialysable ferrous Fe. Freezing had no effect, but lyophilisation of the homogenised muscle caused large decreases in dialysable Fe and dialysable ferrous Fe for both extraction and digestion processes. Lyophilisation also resulted in decreased extraction of peptides, decreased digestion of muscle proteins and reduced levels of sulfhydryl and histidine residues. Results demonstrated that dialysable Fe is produced by acid-soluble low mol. wt. muscle component(s) and also by peptides resulting from digestion of muscle proteins, both of which reduce and chelate Fe. Reduced formation of dialysable Fe by both mechanisms following lyophilisation could be explained by sulfhydryl oxidation and impaired digestion due to protein crosslinking.