Food-processing operations, from premature harvesting
to extended storage and physical treatments, may cause
a loss of aroma (volatile ¯avour) that calls for subse-
quent supplementation. In addition, the steadily in-
creasing market for ¯avours forces suppliers to search
for alternative sources. The conventional routes of
chemical synthesis or isolation from plants are still via-
ble, but the biotechnological generation of aroma com-
pounds is becoming increasingly attractive. Duplicating
plant secondary metabolism in microbial systems (``fer-
mentative processes'') leads to aroma compounds that
are classi®ed as natural by the European and US food
legislation. This label represents a strong marketing
advantage.