3. Bioconversions of agricultural precursors into flavor compounds

With a few exceptions, such as cloves and vanilla beans, most biosynthetically-produced odor compounds are only present in very low concentrations in the producing organism. It is therefore uneconomical to purify molecules of interest from these sources. What is observed in plants is also observed in micro-organisms. Nevertheless, it is often possible to find more or less direct precursors of the molecules of interest for bioconversion. In such cases, concentrations can exceed 10 g/L and production rates of the order of 1 g/(L · h). One of the difficulties with this approach is obtaining sources of precursors in sufficient quantities and at prices compatible with the value of the resulting product.

The problems involved in converting a substrate into aroma compounds can be summarized as follows:

• find the biological...