1. Structure and properties of aroma compounds

1.1 Major classes of active molecules

Flavor compounds are present in foods in very small quantities, with concentrations ranging from a few milligrams per ton to a few milligrams per kilogram; on the other hand, they are generally present in very large numbers. There are 360 compounds in strawberry flavouring, over 600 in coffee flavouring and some 850 in wine flavouring.

The compounds identified among the volatile constituents of foods belong to all classes and series of chemical compounds. Rijkens and Boelens [1] gave the distribution of compounds identified in 1975 as shown in table 1 ; since then, the number of compounds identified...