Effect of high pressure treatment on colour, microbial and chemical characteristics of dry cured loin.

The effect of high pressure on sliced and vacuum packaged commercial dry-cured pork loin was determined by analysing the induced colour changes, the residual enzymatic activities of cathepsins, aminopeptidases and dipeptidilpeptidases and the changes in the content of free amino acids and also its effect on lipid oxidation, as TBARS (Thiobarbituric reactives substances) and volatile flavour compounds. High pressure treatments above 300MPa affected the colour of dry cured pork loins producing an increase in lightness and decreased redness and these differences were detected during all vacuum storage. High pressure produced a reduction in the activity of aminopeptidases and dipeptidylpeptidases. The untreated samples showed an increase in free amino acid content during vacuum storage while the pressurised samples showed no significant increases probably due to the reduction in aminopeptidase activity. The oxidative stability of the pressurised dry-cured loins was not affected as observed by the absence of differences in TBARS values and in the abundance of volatile compounds from the lipid oxidation. However, the pressurised treatment produced a reduction of several flavour compounds, particularly those derived from Maillard reactions, although they are regenerated during vacuum storage. In summary, high pressure treatment after the ripening of dry-cured loin affects its quality but the differences can be minimised by vacuum storage.