Evolution of chemical and sensory properties during aging of top-fermented beer.
The aging and consequent changes in flavor molecules of a top-fermented beer were studied. Different aging conditions were imposed on freshly bottled beer. After 6 months of aging, the concentration changes were recorded for acetate esters, ethyl esters, carbonyls, Maillard compounds, dioxolanes, and furanic ethers. For some flavor compounds, the changes with time of storage were monitored at different temperatures, either with CO(2) or with air in the headspace of the bottles. For some molecules a relationship was determined between concentration changes and sensory evaluation results. A decrease in volatile esters was responsible for a reduced fruity flavor during aging. On the contrary, various carbonyl compounds, some ethyl esters, Maillard compounds, dioxolanes, and furanic ethers showed a marked increase, due to oxidative and nonoxidative reactions. A very high increase was found for furfural, 2-furanmethanol, and especially the furanic ether, 2-furfuryl ethyl ether (FEE). For FEE a flavor threshold in beer of 6 mug/L was determined. In the aged top-fermented beer, FEE concentrations multiple times the flavor threshold were observed. This was associated with the appearance of a typical solvent-like flavor. As the FEE concentration increased with time at an almost constant rate, with or without air in the headspace, FEE (and probably other furanic ethers) is proposed as a good candidate to evaluate the thermal stress imposed on beer.
Vanderhaegen
Bart
B
Centre for Malting and Brewing Science, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Heverlee, Belgium. bart.vanderhaegen@agr.kuleuven.ac.be
Neven
Hedwig
H
Coghe
Stefan
S
Verstrepen
Kevin J
KJ
Verachtert
Hubert
H
Derdelinckx
Guy
G
D001515:Beer / Q000032:analysis*; D003116:Color; D005019:Ethyl Ethers / Q000032:analysis; D005285:Fermentation; D005419:Flavonoids / Q000032:analysis; D005511:Food Handling / Q000379:methods; D005663:Furans / Q000032:analysis; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis; D059808:Polyphenols; D012677:Sensation; D013649:Taste; D013997:Time Factors; D014835:Volatilization
D005019:Ethyl Ethers; D005419:Flavonoids; D005663:Furans; D010636:Phenols; D059808:Polyphenols