Abstract: This study investigated the effects of treatment with different concentrations of sodium chloride (NaCl) on the characteristics of intramuscular collagen and related endogenous enzyme activities in beef during 72 h postmortem in order to provide theoretical evidence that NaCl contributes to improving postmortem beef tenderness. Enzyme-linked immunosorbent assay (ELISA) was used to determine the changes in the level of mature collagen cross-linking and endogenous enzyme activities in bovine longissimus dorsi muscle after being treated with 1% or 3% (m/m) NaCl solution. At the same time, differential scanning calorimetry (DSC), endogenous and exogenous fluorescence spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to determine physicochemical properties such as thermal solubility, thermal stability, surface hydrophobicity to characterize the structural changes and degradation status of collagen. The results showed that treatment of NaCl at both concentrations could regulate the activity of lysine oxidase, β-glucuronidase and β-galactosidase in beef during 72 h postmortem, thereby enhancing the thermal solubility of intramuscular collagen, reducing the thermal stability, promoting conformational changes and degradation of collagen and ultimately contributing to improving the tenderness of postmortem beef.

Key words: NaCl; characteristics of intramuscular collagen; proteoglycan; postmortem aging; shear force; enzyme activity