title: Ferulic acid release and 4-vinylguaiacol formation during brewing and fermentation: indications for feruloyl esterase activity in Saccharomyces cerevisiae.
abstract: The release of ferulic acid and the subsequent thermal or enzymatic decarboxylation to 4-vinylguaiacol are inherent to the beer production process. Phenolic, medicinal, or clove-like flavors originating from 4-vinylguaiacol frequently occur in beer made with wheat or wheat malt. To evaluate the release of ferulic acid and the transformation to 4-vinylguaiacol, beer was brewed with different proportions of barley malt, wheat, and wheat malt. Ferulic acid as well as 4-vinylguaiacol levels were determined by HPLC at several stages of the beer production process. During brewing, ferulic acid was released at the initial mashing phase, whereas moderate levels of 4-vinylguaiacol were formed by wort boiling. Higher levels of the phenolic flavor compound were produced during fermentations with brewery yeast strains of the Pof(+) phenotype. In beer made with barley malt, ferulic acid was mainly released during the brewing process. Conversely, 60-90% of ferulic acid in wheat or wheat malt beer was hydrolyzed during fermentation, causing higher 4-vinylguaiacol levels in these beers. As cereal enzymes are most likely inactivated during wort boiling, the additional release of ferulic acid during fermentation suggests the activity of feruloyl esterases produced by brewer's yeast.
authors.affiliation: Centre for Malting and Brewing Science, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium. Stefan.Coghe@agr.kuleuven.ac.be
authors.forename: Stefan
authors.initials: S
authors.lastname: Coghe
authors.forename: Koen
authors.initials: K
authors.lastname: Benoot
authors.forename: Filip
authors.initials: F
authors.lastname: Delvaux
authors.forename: Bart
authors.initials: B
authors.lastname: Vanderhaegen
authors.forename: Freddy R
authors.initials: FR
authors.lastname: Delvaux
mesh_terms: D001515:Beer / Q000032:analysis / Q000382:microbiology*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism*; D002523:Edible Grain; D005285:Fermentation; D006139:Guaiacol / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism*; D006358:Hot Temperature; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000378:metabolism; D014908:Triticum
chemical_list: D003373:Coumaric Acids; D006139:Guaiacol; C014245:4-vinylguaiacol; C004999:ferulic acid; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase