title: On the origin of free and bound staling aldehydes in beer.
abstract: The chemistry of beer flavor instability remains shrouded in mystery, despite decades of extensive research. It is, however, certain that aldehydes play a crucial role because their concentration increase coincides with the appearance and intensity of "aged flavors". Several pathways give rise to a variety of key flavor-active aldehydes during beer production, but it remains unclear as to what extent they develop after bottling. There are indications that aldehydes, formed during beer production, are bound to other compounds, obscuring them from instrumental and sensory detection. Because freshly bottled beer is not in chemical equilibrium, these bound aldehydes might be released over time, causing stale flavor. This review discusses beer aging and the role of aldehydes, focusing on both sensory and chemical aspects. Several aldehyde formation pathways are taken into account, as well as aldehyde binding in and release from imine and bisulfite adducts.
authors.affiliation: Laboratory of Enzyme, Fermentation and Brewing Technology, KAHO Sint-Lieven University College, KU Leuven Association, Gebroeders De Smetstraat 1, 9000 Gent, Belgium. jeroen.baert@kahosl.be
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Baert
authors.forename: Jessika
authors.initials: J
authors.lastname: De Clippeleer
authors.forename: Paul S
authors.initials: PS
authors.lastname: Hughes
authors.forename: Luc
authors.initials: L
authors.lastname: De Cooman
authors.forename: Guido
authors.initials: G
authors.lastname: Aerts
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D001515:Beer / Q000032:analysis*; D005421:Flavoring Agents / Q000737:chemistry*; D006801:Humans; D013649:Taste
chemical_list: D000447:Aldehydes; D005421:Flavoring Agents