Role of lysosomes and their cathepsins B and L in Atlantic salmon (Salmo salar L.) muscle structure integrity, texture and final quality

 Cathepsin activity: Measure the release of the fluorogenic reagent 7-amido-4-methylcoumarin. Different substrates for cathepsins B+L and B. • Cathepsin B+L, B and L total activity measured in muscle homogenates when treatment applied premortem . The more the cathepsin activity, the greater the muscle degradation. •Cathepsins B+L lysosomal activity measured in the isolated fraction of muscle lysosomes when treatment applied post-mortem. The less the cathepsin B+L activity, the more the cathepsins released from the lysosomes and the greater the muscle degradation.  Cathepsin B and L gene expression measured with PCR.  Light microscopy, plastic embedding, toluidine blue staining: Counting detachments between muscle fibres (myofibres). The more the percentage of detachments, the more the degradation of the muscle HISTOLOGY