EVALUATION OF CATHEPSIN-B LEVELS IN FRESH THIGHS SELECTED FOR CURED RAW HAM PRODUCTION

Excessive meat tenderization in cured raw Parma ham has recently been correlated with abnormal levels of cathepsin B in freshly slaughtered thigh meat. We have developed a visual assay employing the substrate Z -Arg-Arg-NNapOMe for the quantitative detection of active cathepsin B levels in pork thigh muscle homogenates. The work was based on a kinet ic characterization, in steady state condition, of pig muscle cathepsi n B with several peptidyl chromophoric substrate analogs. This assay c an easily and safely be performed by non-specialized personnel directl y in the slaughterhouse or in the factory, for an early quality evalua tion of thighs selected for Parma ham production. Our characterization has further indicated that the catalytic properties of porcine muscle cathepsin B and those of isoforms from other animal and plant species are practically identical. This is particularly evident in the commer cially available bovine spleen isoform, which was employed as a model enzyme in most of the experiments. (C) 1997 Elsevier Science Ltd.