Ir. W.A.M. Wolken : Production of natural flavour compounds

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22 Apr 2003 16:00
Unit: Wageningen University
Location: Aula (gebouw 362), Gen. Foulkesweg 1, Wageningen
Promotor: prof.dr.ir. J. Tramper (Bioprocess Engineering)
Co Promotor: dr.ir. M.J. van der Werf (TNO-Voeding, Zeist)

 Consumers prefer natural over artificial additives. Consequently natural flavour-compounds fetch higher prices than the corresponding artificial compound. Various natural means of flavour production are discussed in this dissertation. The major part is focused on the biotransformation of geraniol into the flavour-compound methylheptenone by spores of the fungus Penicillium digitatum. The biotransformation pathway was elucidated and a unique enzyme in this pathway, citral lyase, was purified from the spores. This cofactor-independent enzyme, combining the actions of a hydratase with that of an aldolase, converts citral, an intermediate of the geraniol conversion, in addition to other ?,?-unsaturated aldehydes. Furthermore, spores were found to be on average 2.5 times more resistant to the toxic effects of the substrates, intermediates and products of the geraniol conversion. Finally, this dissertation describes the use of amino acids as catalysts in the production of natural flavour compounds. They can for instance be used to catalyse the conversion of cinnamaldehyde into the second most applied flavour compound, benzaldehyde.
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