Assay of Cathepsin D activity in fresh pork muscle and dry-cured ham

Different assays of cathepsin D activity in both porcine muscle and dry-cured ham extracts have been tested in order to find the best conditions for a reliable detection of cathepsin D in dry-cured meat products. The enzyme was effectively extracted with 0·2% (v/v) of Triton X-100. Nucleases if present were not observed to interfere with the assays. The best conditions for a reliable detection of cathepsin D in dry-cured ham were found to be the incubation of the enzyme extract for 1 h at 45°C in a reaction mixture containing 0·60% (w/v) of haemoglobin in 0·2 m sodium citrate buffer, pH = 3·7.