Biotechnology of Flavours
Microbial systems produce flavours with the attractive attribute „natural“. Experiments using labeled precursor substrates on the shake flask scale help to elucidate the frequently unknown metabolic pathways. Two independent pathways for the synthesis of the furanoterpenoid rose fragrance Perillene exist in Pleurotus ostreatus, running from ß-Myrcene through Epoxides or Endoperoxides to the product.
The biotechnological production of the grapefruit character impact component Nootkatone has been intensively researched. A dioxygenase of Pleurotus sapidus transforms the precursor (+)-Valencene, likewise through a stereospecific allylic hydroperoxidation reaction, to the desired flavour. Yields of more than one gram per liter pave the way to the first industrially useable transformation of a sesquiterpene.
Biocatalysis and chemical (aut)oxidation have to be strictly separated in such kind of work. This is supported by the analysis of regio and stereo-selectivity. In vivo ESR spin trapping methods detect radical intermediates. Nonvolatile metabolites are analyzed using LC-MS in its various ionization and collision methods.