10

Upvote on the question, and someone will undoubtedly come by with a better answer, but here goes off the top of my head: Acetaldehyde (a-cee-tal-de-hide....nobody says it right!) is a precursor to alcohol. It is an intermediate compound that is formed prior to the formation of EtOH/ethanol during fermentation. So the weird thing is that acetaldehyde is ...


6

Given that it happens a long time after your beer has reached FG, I doubt it's due to insufficient oxygen in the wort at pitching time. If it were insufficient oxygen, that would lead to a poor ferment, with the CH3CHO being created as the penultimate step in fermentation (conversion of pyruvate into acetaldehyde and carbon dioxide) but the poor fermentation ...


3

Several causes and solutions, in this case I would say a combination of premature flocculation, lack of oxygen pre pitch, under pitched and possibly post fermintation o2 exposure. Solution so you don't get a 4th batch like this. 1)Areate wort before pitching yeast, consider direct o2 gas. 2) Use a yeast starter to solve the underpitch and premature ...


2

I've never tried heating beer, although given that commercial beer is pasteurized at around 165F/74C - far above your 20.2C/68F it may work. I'm not a chemist, but my understanding is that the 68F boiling point is for the pure substance - once dissolved in water the boiling point will change, the same as when salt is added to water changes the freezing and ...


2

There's really not a set time for this senerio, but time and conditions may improve the beer. Acetaldehyde is produced in early fermentation then later cleaned up in later stages and aging. It's identified by a green Apple aroma and in bad cases as a cidery taste. This may be the "sour" taste that reduced in the steps you mentioned. It may clean up in ...


2

Acetaldehyde is most often caused by aeration of the wort. I would suggest trying a batch where you do not rack to secondary, as this could be the point in time where the oxidation is occurring. Or you could try purging the secondary vessel with CO2 prior to racking. Also make sure that you have a good solid flow of wort during racking, the introduction ...


2

If your problem really is the O2, I would get something like this: http://www.amazon.co.uk/Water-Butt-Homebrew-Fermenter-Black/dp/B00R6GJY7G/ No more removing the lid and it makes bottling so much easier. What exactly are you trying to brew?


2

The smell of apples is totally normal in beer fermentation. The chemical compound acetaldehyde gives the characteristic green-apple flavor and aroma. It's an intermediate in the synthesis of ethanol from glucose by yeast. Usually warm conditioning is enough to reduce levels to below flavor threshold. Factors like not pitching enough yeast or not ...


1

It is quite possible that a lactobacillius or other similar lactobacter has infected the beer. If the taste is not to your liking I would recommend leaving the beer for (say) another 6 weeks (or longer) in the bottle and re-tasting. After 3 months if it is still sour then it will not improve. Acetal (AKA acetaldehyde) which is usually associated with a tart ...


1

Chlorine in your water can be perceived as a sour taste if it causes chlorophenols in your beer Does your water have chlorine and if so, sis you do anything to remove it?


1

Acetaldehyde after bottling is a classic sign of oxygen exposure, and is the main reason we wait a week or more before drinking bottled homebrew. Noticeable CO2 shows up in just a few days, but the acetaldehyde (normal byproduct of glycolysis) only gets converted to alcohol later, when there is no more oxygen around. From your procedure, I think you are ...


1

The other contributor to Acetaldehyde in beer is excessive aging on yeast. As the yeast cells stress, and eventually die, they can lyse (burst) and release AA from the cell interior into the beer. This happens a lot with big, high alcohol beers, because often they have trouble getting to the end fermentation, so the brewers prolong the fermentation time on ...


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