Chemoenzymatic synthesis of aroma active 5,6-dihydro- and tetrahydropyrazines from aliphatic acyloins produced by baker's yeast.
Twenty-five acyloins were generated by biotransformation of aliphatic aldehydes and 2-ketocarboxylic acids using whole cells of baker's yeast as catalyst. Six of these acyloins were synthesized and tentatively characterized for the first time. Subsequent chemical reaction with 1,2-propanediamine under mild conditions resulted in the formation of thirteen 5,6-dihydropyrazines and six tetrahydropyrazines. Their odor qualities were evaluated, and their odor thresholds were estimated. Among these pyrazine derivatives, 2-ethyl-3,5-dimethyl-5,6-dihydropyrazine (roasted, nutty, 0.002 ng/L air), 2,3-diethyl-5-methyl-5,6-dihydropyrazine (roasted, 0.004 ng/L air), and 2-ethyl-3,5-dimethyltetrahydropyrazine (bread crustlike, 1.9 ng/L air) were the most intensive-smelling aroma active compounds.
Nestlé Research Center, Vers-chez-les-Blanc, P.O. Box 44, 1000 Lausanne 26, Switzerland.
Toshinari
T
Kurniadi
Rachid
R
Bel Rhlid
Laurent-Bernard
LB
Fay
Marcel-Alexandre
MA
Juillerat
Ralf Günter
RG
Berger
D000447:Aldehydes / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D002384:Catalysis; D005233:Fatty Alcohols / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D009812:Odorants / Q000032:analysis; D011719:Pyrazines / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D000447:Aldehydes; D002264:Carboxylic Acids; D005233:Fatty Alcohols; D011719:Pyrazines; C011159:acyloin