Evolution of Chemical and Sensory Properties during Aging of Top-Fermented Beer

Abstract

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.

Sensory and Instrumental Flavour Analysis of Wort Brewed with Dark Specialty Malts

“…Wort samples were evaluated by purge and trap GC/ MS according to Vanderhaegen et al 44 , using a slightly modified procedure. Prior to analysis, 200 µL internal standard (200 mg/L pentanol) and 200 µL of a 10% antifoam solution (Sigma-Aldrich Chemie GmbH, Munich, Germany) were added to 50 mL of wort.…”

“…The formed aminoketones may subsequently be converted to the corresponding pyrazines 43 . The Maillard reaction can also lead to the development of vicinal diketones during beer aging 44 . The importance of vicinal diketones during aging has partially been elucidated.…”

The Peroxide Challenge Test: A Novel Method for Holistic Near-Real Time Measurement of Beer Flavour Stability

“…Finally, beer will become woody and winey (sherry-like). The extent to which these changes occur will differ from beer to beer and the solutions to the problem will similarly vary 18,19,30 .…”

Discrimination of Beer Flavours by Analysis of Volatiles Using the Mass Spectrometer as an Electronic Nose

“…Common methods to study beer volatiles are chromatographic separation techniques including GC and, particularly, sensory analyses (panel tests) in the brewing practice 1,3,4,12,16 . Gas chromatography with mass spectrometry detection (GC-MS) offers a powerful tool to identify and quantify volatile beer compounds.…”