The role of bacterial enzymes, both from autochthonous meat bacteria and starter cultures, in flavour development of fermented meat products remains unclear, in particular when their effects are related to the contribution of meat enzymes. Since bacteria are believed to act more on the protein fraction of muscle than on lipids, the focus of this project will be on proteolysis and amino acid conversion. Moreover, the yet poorly understood protein oxidation phenomenon will be studied. To measure protein breakdown, two-dimensional gel electrophoresis coupled to mass spectrometry analysis will be applied for the first time to fermented meats. This will be coupled to specific analysis of meat protein oxidation. Volatile production, mainly through bacterial amino acid conversions, will be quantified by mass spectrometry. A distinction will be made between coagulase-negative staphylococci, lactobacilli, and several lactic acid bacteria that are less common in meat but offer interesting aroma-generating potential. Kinetics of the bacterial effects will be investigated to map inter- and intraspecies variability. The combined action of peptide-generating meat enzymes and peptide-converting bacterial activities will be studied as a function of time and meat fermentation conditions, to unravel their differential and specific roles.