The effects of conditioning on meat collagen: Part 3-Evidence for proteolytic damage to endomysial collagen after...

The effects of conditioning on the endomysial fraction of bovine meat were investigated. Solubility studies on endomysial connective tissue and analysis of insoluble endomysial fractions remaining after conditioning were carried out. Yields of soluble endomysial fractions represented, on average, 94·5% of total extracted endomysial material for unconditioned muscles compared with 97·5% for conditioned muscles. Soluble endomysial fractions contained, on average, 0·13% collagen from unconditioned muscles and 0·22% collagen from conditioned muscles. The main peptide components observed on analysis of insoluble endomysial fractions after CN Br digestion were derived from types I and III collagen. Changes observed on the peptide maps, evident as the appearance of a number of new bands from conditioned samples, appeared to be muscle specific. The amount of type III collagen relative to type I decreased on conditioning, indicating that endomysial type III collagen was preferentially destroyed during conditioning. Two-dimensional polyacrylamide gel electrophoresis maps revealed new peptide material in the molecular weight range 40 000 to 50 000 on conditioning. These data provide direct evidence of the effect of proteolytic processing on endomysial collagen during conditioning.