Age‐Associated Changes in Bovine Muscle Connective Tissue. III. Rate of Solubilization at 100°C a

SUMMARY The rate of solubilization of insoluble connective‐tissue residues obtained from the loose connective‐tissue network within bovine biceps femoris muscle was studied in phosphate‐buffered (pH 7.0) aqueous medium at 100°C. Eleven animals from four age groups were used: Group I, three veal calves, 40–49 days old; Group II, three steers, 403–495 days old; Group III, three cows, 4 years, 8 months to 5 years, 5 months old; Group IV, two cows, 10 years, 2 months and 10 years, 5 months old. The conditions under which the samples were heated resulted in the solubilization of 95–100% of the hydroxyproline and 72–94% of the protein in the samples within 240 min. The release of soluble protein and soluble hydroxyproline indicated that collagen from the younger animals was solubilized (i.e. converted to gelatin) much more rapidly than collagen from the older animals. The low hydroxyproline content of the soluble protein released from the Group I samples was discussed, and it was suggested that these samples contained some reticulin. The average molecular weight of the soluble protein decreased with increasing age. The findings were discussed with relation to the results reported in two previous papers and the extent and strength of cross‐linkages in collagen from animals of different ages. It was suggested that the number and strength of cross‐linkages in collagen may play an important role in meat tenderness.