title: Biosynthetic origin of geosmin in red beets (Beta vulgaris L.).
abstract: Geosmin provides the characteristic but sometimes undesirable "earthy" flavor to red table beets. To date, it is not known whether geosmin is a byproduct of beet metabolism or synthesized by soil-borne microorganisms and taken up by the beets during maturation. Analysis of mature beet roots revealed that peels contained 6 times the amount of geosmin compared to the bodies and cores. Sterilized beet seeds were aseptically grown in a basal medium prior to analysis for the presence of geosmin. Using a headspace solid-phase microextraction (HSPME) method, the relative recovery of geosmin from beet seedling extracts was 72.0 +/- 4.2% with (-)-menthone as the internal standard. The presence of geosmin in aseptically grown beet seedlings was confirmed by gas chromatography-mass spectrometry using authentic geosmin as the standard. During aseptic growth, the concentration of geosmin in seedlings remained constant for up to 5 months but increased at 6 months. Geosmin added to the growth medium was not absorbed by the seedlings. These studies support the conclusion that red beets are capable of endogenous synthesis of geosmin.
authors.affiliation: Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376, USA. gpl@uky.edu
authors.forename: Guiping
authors.initials: G
authors.lastname: Lu
authors.forename: Charles G
authors.initials: CG
authors.lastname: Edwards
authors.forename: John K
authors.initials: JK
authors.lastname: Fellman
authors.forename: D Scott
authors.initials: DS
authors.lastname: Mattinson
authors.forename: John
authors.initials: J
authors.lastname: Navazio
mesh_terms: D027461:Beta vulgaris / Q000737:chemistry / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D009284:Naphthols / Q000032:analysis* / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry; D036226:Seedlings / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009284:Naphthols; D010936:Plant Extracts; C001278:geosmin