Hammer, A.K.A.K.HammerEmrich, N.O.N.O.EmrichOtt, J.J.OttBirk, F.F.BirkFraatz, M.A.M.A.FraatzLey, J.P.J.P.LeyGeissler, T.T.GeisslerBornscheuer, U.T.U.T.BornscheuerZorn, H.H.Zorn2022-03-062022-03-062021https://publica.fraunhofer.de/handle/publica/26884810.1021/acs.jafc.0c06872Lipid extracts of the fungus Flammulina velutipes were found to contain various scarce fatty acids including dodec-11-enoic acid and di- and tri-unsaturated C16 isomers. A biotechnological approach using a heterologously expressed carboxylic acid reductase was developed to transform the fatty acids into the respective aldehydes, yielding inter alia dodec-11-enal. Supplementation studies gave insights into the fungal biosynthesis of this rarely occurring acid and suggested a terminal desaturation of lauric acid being responsible for its formation. A systematic structure-odor relationship assessment of terminally unsaturated aldehydes (C7-C13) revealed odor thresholds in the range of 0.24-22 mg/L in aqueous solution and 0.039-29 ng/L in air. In both cases, non-8-enal was identified as the most potent compound. All aldehydes exhibited green odor qualities. Short-chained substances were additionally associated with grassy, melon-, and cucumber-like notes, while longer-chained homologs smelled soapy and coriander leaf-like with partly herbaceous nuances. Dodec-11-enal turned out to be of highly pleasant scent without off-notes.en540631571572journal article