The influence of environmental parameters on the catabolism of branched-chain amino acids by Staphylococcus xylosus and Staphylococcus carnosus Original Research Article

Degradation of the amino acids leucine, isoleucine and valine into branched flavour compounds by Staphylococcus xylosus and Staphylococcus carnosus was studied using resting cell cultures added to a defined reaction medium under different environmental conditions relevant to sausage fermentation. The environmental conditions studied were temperature (12–28°C), NaCl concentration (4.0–12.0% (w/w)) acidity (pH 4.8–5.8) and addition of manganese (0–2.5 mg Mn/kg). Flavour compounds were sampled by automatic static headspace collection and separated/quantified using gas chromatography/flame ionization detection (GC/FID). Main volatile catabolic products of leucine, isoleucine and valine were 3-methylbutanoic, 2-methylbutanoic and 2-methylpropanoic acids, respectively. The generation of branched flavour compounds was influenced significantly by most of the investigated environmental parameters, but in particularly by temperature and NaCl.