title: How low pH can intensify beta-damascenone and dimethyl trisulfide production through beer aging.
abstract: Flavor quality is of major importance to the consumer, but the flavor characteristics of beer appear to deteriorate greatly with time, at a rate depending on the composition of the beer and its storage conditions (notably pH). Prior to identifying the influence of pH on the development of the most intense staling flavors found in aged lager beers, the corresponding key flavor compounds were determined by aroma extract dilution analysis. In addition to trans-2-nonenal, beta-damascenone seems at least as important in the flavor of aged beer. Ethyl butyrate, dimethyl trisulfide, 2-acetylpyrazine, 3-(methylthio)propionaldehyde, 2-methoxypyrazine, maltol, gamma-nonalactone, and ethyl cinnamate are also relevant to the sensory profile of aged beer. Upon aging, a beer having a higher pH produces less beta-damascenone, because acid-catalyzed glycoside hydrolysis is decreased. On the other hand, it produces more 3-(methylthio)propionaldehyde, owing to Strecker degradation of methionine. Raising the beer pH additionally causes the release of 3-(methylthio)propionaldehyde from sulfitic adducts. These adducts, more stable at a lower pH, protect the aldehyde against premature oxidation to 3-(methylthio)propionic acid, thus making it available for dimethyl trisulfide formation during aging.
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Faculté d'Ingénierie biologique, agronomique et environnementale, Université catholique de Louvain, Croix du Sud, 2 bte 7, Belgium.
authors.forename: Laurence
authors.initials: L
authors.lastname: Gijs
authors.forename: Fabienne
authors.initials: F
authors.lastname: Chevance
authors.forename: Vesna
authors.initials: V
authors.lastname: Jerkovic
authors.forename: Sonia
authors.initials: S
authors.lastname: Collin
mesh_terms: D001515:Beer / Q000032:analysis*; D002849:Chromatography, Gas; D005524:Food Technology; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D045792:Norisoprenoids; D013440:Sulfides / Q000032:analysis* / Q000737:chemistry; D013649:Taste; D013729:Terpenes / Q000032:analysis* / Q000737:chemistry; D013997:Time Factors
chemical_list: D045792:Norisoprenoids; D013440:Sulfides; D013729:Terpenes; C054170:dimethyl trisulfide; C075388:beta-damascenone