Microbial flavors

Side streams of classical biotechnological processes, such as cheese starte r culture distillates or wine lees oil have a long tradition as flavoring m aterials. The first concerted application of biocatalysis arose with the av ailability of solvent-tolerant, microbial lipases to produce volatile ester s from reverse hydrolysis or transesterification; this is, like some other fatty acid based processes, now an industrial reality. Microorganisms, howe ver, are not only key to modern biotechnology, but represent advantageous e xperimental systems for the elucidation of flavor formation pathways. The m icrobial metabolism of L-phenylalanine can serve as an example for the ampl e variety of volatile products. A pathway towards 4-(4-hydroxyphenyl)-butan -2-one (raspberry ketone, Frambinone), one of the character impact componen ts of raspberry flavor, was evaluated in submerged cultured cells of Nidula ria fungi using deutero- and C-13-labeled L-phenylalanines and compared wit h a pathway proposed for raspberry fruit and plant tissue culture.