PHYSICAL AND CHEMICAL PROPERTIES OF EPIMYSIAL ACID-SOLUBLE COLLAGEN FROM MEATS OF VARYING TENDERNESS

SUMMARY: Components of the molecular structure of epimysial acid-soluble collagen (ASC) from meats of varying tenderness were studied by several methods. The ASC was studied since it contains an appreciable amount of intramolecular cross-links but is still soluble. Though the amount of total collagen in epimysial tissue was found to have no correlation with meat tenderness, the molecular studies indicated some correlation of the type of epimysial ASC with meat tenderness. Sucrose density-gradient ultracentrifugation analyses of denatured epimysial ASC suggested that this type of collagen contains a lesser degree of cross-links when obtained from tender meat samples. Viscosity measurements were found to be correlated to tenderness of meat in a manner similar to the results obtained by ultracentrifugation, in that the intrinsic viscosity of epimysial ASC from tender meat was lower than that from tough meat, indicating differences among the relative sizes of the collagen molecules from the different samples. Partial amino acid analyses of the epimysial ASC samples via gas chromatography showed no differences in the levels of aspartic, serine or hydroxyproline, amino acids which may be involved in the ester type of cross-links. Results of chemical estimation of the ester type of cross-links indicated that the proportions of esters in the various ASC samples were similar. The amount of lysine was found to be significantly higher ( P < 0.05) in epimysial ASC from tough meat compared to tender meat, suggesting an increased potential of the aldehydic-type of cross-link, which is formed via an aldol condensation of two aldehydes derived biosynthetically from lysine. This was strengthened by the results obtained in the chemical estimation of the aldehydic-type of cross-link, in that the epimysial ASC of tough meat contained significantly more aldehyde than did that of tender meat ( P <0.05).