Our aim is to comply with the EU-CEN standard for histamine and tyramine. To do so, we determine the numbers of lactic acid bacteria present in various foods by means of our RealTimePCR systems and attempt to establish a correlation between the number of bacteria and the metabolites formed. A similar procedure is used with microorganisms which may produce undesirable by-products such as toxins (e.g. aflatoxin (Aspergillus flavus or Aspergillus parasiticus), patulin (Byssochlamys fulva) or ochratoxin A (Penicillium expansum)) and undesirable olfactory substances (Alicyclobacillus acidoterrestris (guaiacol), Penicillum expansum (geosmin)), respectively.