Effects of retort sterilization and oxygen on the coloration of beef meatballs during storage: Oxidation-reduction reaction underlying meat color pinking

This study investigated the effects of retort sterilization and oxygen on meat coloration during storage of beef meatballs. Beef meatballs were prepared and retort-sterilized under different oxygen concentrations, and color changes were observed after 12 weeks of storage. In the beef meatballs processed in 21 % oxygen, the center cross-section became remarkably pinked with significantly increased a* value, resembling the undesirable persistent pinking in beef. In addition, the outer cross-section turned brown. The oxidation-reduction potential value of the pink cross-section was significantly lower than that of the brown cross-section, although the pH did not change. In addition, oxygen consumption appeared to occur after retort sterilization of the meatballs, and an assay of thiol group concentration, carboxyl compounds, and iron ion valence indicated the oxidation of salt-soluble proteins in browned meatballs. These findings suggest that the observed pinking phenomenon resulted from alterations in the oxidation-reduction state of the meat during storage.