Acetaldehyde
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Sometimes a wine can be called flabby or dull, nutty or musty. These are typical traits of an acetaldehyde character in red or white wines, which is generally considered undesirable. Wines with an aldehydic perception have often been exposed to too much oxygen.[1]
Acetaldehyde formation during fermentation can be reduce by limiting sulfite usage as well as providing proper yeast nutrition, particularly thiamine at the time of pitching.[citation needed] See Nutrition for more information.
Acetaldehyde formation during wine aging can be prevented and/or removed by proper sulfite level maintenance.[citation needed]
Ascorbic acid does not significantly affect acetaldehyde levels in wine when added after the yeast is removed.[2]
Yeast uptake aldehydes at the end of fermentation in order to regenerate reduced coenzymes such as NADP and NADPH using aldoketoreductase enzymes.[3]
acetaldehyde is formed at the early stage of refermentation by the yeast and is not reduced as long as oxygen is present in the beer[4]
A study on the influence of acetaldehyde from beer on haze formation and stability of beer phenolics reported that beer pH is influenced by acetaldehyde, which results in a reduction of catechin content and haze formation [105].[5][6]
The hydroxyethyl radical is probably one of the most abundant in beer, owing to the high concentration of ethanol present ( Andersen et al., 2000 ). The hydroxyethyl radical can degrade to produce acetaldehyde ( Andersen and Skibsted, 1998 ).[7]
Acetaldehyde is an aldehyde that is difficult to categorize under just one specific formation mechanism. It is sometimes called a “Strecker aldehyde”, because it can be formed by Strecker degradation of alanine.23,123 Furthermore, acetaldehyde is formed as a byproduct of glycolysis during fermentation, up to levels of 40 mg/L. Moreover, ethanol can be oxidized to acetaldehyde in a free radical mechanism involving the Fenton reaction. Beer is predominantly a water−ethanol solution, with ethanol being the most abundant organic molecule present. Not surprisingly, the 1-hydroxyethyl radical is the most abundant free radical in beer, originating from the reaction of ethanol with a hydroxyl radical.157 This 1-hydroxyethyl radical can bind oxygen, resulting in acetaldehyde and a hydroperoxyl radical, which propagates the radical chain reaction.[8]
Elevated presence of malt-derived fatty acids (e.g. from excess trub) may decrease the formation of acetaldehyde.[9]
- https://www.awri.com.au/industry_support/winemaking_resources/sensory_assessment/recognition-of-wine-faults-and-taints/wine_faults/
- http://pubs.ub.ro/dwnl.php%3Fid%3DCSCC6201011V03S01A0006
- https://www.google.com/url?sa=t&source=web&rct=j&url=http://pubs.ub.ro/dwnl.php%3Fid%3DCSCC6201011V03S01A0006&ved=2ahUKEwjH-LHUsb7oAhXJGs0KHSiiC04QFjALegQIBBAB&usg=AOvVaw3r83U5nujMZpsIDLfA-2mA&cshid=1585443847695
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4700919/
References[edit]
- ↑ Williamson, B. "Recognizing Wine Flaws." Williamson Wines. Accessed online March 2020.
- ↑ Marks, AC, and Morris, JR. "Ascorbic acid effects on the post-disgorgement oxidative stability of sparkling wine." Am J Enol Vitic. vol. 44, 1993, pp. 227–231.
- ↑ Van Landschoot, A., et al. "Effect of pitching yeast preparation on the refermentation of beer in bottles." Cerevisia, vol. 29, no. 3, 2004, pp. 140–146.
- ↑ De Francesco G, Bravi E, Sanarica E, Marconi O, Cappelletti F, Perretti G. Effect of addition of different phenolic-rich extracts on beer flavour stability. Foods. 2020;9(11):1638.
- ↑ Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. Beer polyphenols—bitterness, astringency, and off-flavors. Beverages. 2021;7(2):38.
- ↑ Wannenmacher J, Gastl M, Becker T. Phenolic substances in beer: Structural diversity, reactive potential and relevance for brewing process and beer quality. Compr Rev Food Sci Food Saf. 2018;17(4):953–988.
- ↑ Bamforth CW, Lentini A. The flavor instability of beer. In: Bamforth CW, ed. Beer: A Quality Perspective. Academic Press; 2009:85–109.
- ↑ Baert JJ, De Clippeleer J, Hughes PS, De Cooman L, Aerts G. On the origin of free and bound staling aldehydes in beer. J Agric Food Chem. 2012;60(46):11449–11472.
- ↑ Gibson BR. 125th anniversary review: improvement of higher gravity brewery fermentation via wort enrichment and supplementation. J Inst Brew. 2011;117(3):268–284.