Proteoglycans and meat quality - A possible role of chondroitin/dermatan sulfate proteoglycans in post mortem degradation

The knowledge of components involved in post mortem degradation of striated muscle is of great importance for the meat industry in order to provide tender meal for the consumer. To address this problem the present study has focused on proteoglycans. Proteoglycans were extracted from meat (M. semimembranosus) stored for 0, 7, 14 and 21 days post mortem by use of denaturing agents. The content of glycosaminoglycans (GAGs) in the extracts showed a reduction during post mortem storage of meat whereas the protein content showed a small increase. The reduction in GAGs could be explained by degradation of proteoglycans of high as well as low molecular mass judged by gel filtration, ion exchange chromatography and electrophoresis. Among the low molecular size PG, decorin was identified by use of antibodies and Western blotting. This collagen interacting molecule was shown to be degraded during post mortem storage. Furthermore it was shown by ion-exchange chromatography and electrophoresis that the degradation of decorin involved both the peptide core and the GAG side chains. Judged by immunohistochemistry the proteoglycans involved in degradation showed a widespread distribution in the extracellular matrix.