The "Sixth Weurman Symposium" was held from May 2nd to May 4th 1990 in Geneva. Nearly 150 scientists from university and industry, coming from 18 countries, attended the Geneva Research Conference Flavour 90. The present volume contains most of the contributions presented during this meeting as oral communications and posters, representing the following topics - the Chemistry of Flavours, energy Application and Food Flavour Systems, and instrumentation and Data Treatment. The first topic covers the production of nature-identical aroma constituents via chemical synthesis and with the help of biotechnological methods including the interaction of food flavour ingredients under "processing" conditions. Although the modern flavourist, if he wants his tailor-made compounds to be highly original, cannot do without synthetic equivalents of naturally occurring aroma constituents for his creative work, the chemist disposes of only very few methods for their production. This fact is all the more dramatic, as during the last two decades more that 6000 volatile flavour constituents have been discovered.
The special value of all these chemicals lies in the knowledge of their sensory properties, as well as their physical, chemical ad organoleptic behaviour in food systems. The papers also address the importance of optical activity. Enantiodiscrimination of chiral flavour consitituents is now a well-established fact, and enantioselective syntheses and resolution techniques with high enantiomeric excess will certainly occupy the flavour chemist in the future.