ABSTRACT
Traditional fermentations use the ability of microorganisms to transform raw materials in complex food products. This process of biotransformation involves a wide range of biochemical reactions that depend on both the microorganism used and its direct environment. Since the 1980s, biotechnologists have tended to exploit this biological capacity in order to produce high value added products, especially aroma or flavor compounds. During the last twenty years, a large number of reviews and contributions discussing the possible industrial applications of microbial volatiles have been published (1-13). In spite of many advances in cell biology, enzymology, genetic engineering, and process control, and considering the high demand and commercial value of natural flavors, to date about 15% of natural flavoring molecules are produced as pure compounds by biotechnological means. This is principally explained by economic constraints that limit the industrial scaling up of many laboratory processes. However, the recent development of genetic engineering tools as well as new investigations on the direct control of the biocatalyst environment via redox potential or hydrophobicity and polarity opens novel and innovating developments in this field. Such developments may help to overcome the limits encountered and widen the spectrum of biotechnologically accessible flavor compounds.
