The Science of Aging Beer?

Bottle-conditioned beers contain active yeast which are feeding on sugars and will ferment the beer as long as you store it, lending the beer new flavors and complexities as it ages.


Cheers!

 

"Active" yeast that continues to "ferment the beer" is more likely to result is broken bottles and a nasty mess on one's cellar floor. (Keep the heavy gloves and mop & bucket handy).

 

Unless the beer contains some sort of bugs, this is false. Once the beer is fully fermented, there just aren't any sugars left for the yeast to consume.

That said, I'd like to hear if anyone knows more about this subject as well.

 

Guess I was wrong. Can't win em all.

Cheers!

 

Here are some of the things that can happen...

- The beer will oxidize if there is any O2 present
- Phenols will drop out, leaving the beer less astringent
- If fermentation byproducts (diacetyl, acetaldehydes, etc.) had not been cleaned up completely, and the aging beer is warm enough, the yeast (if present) may continue the cleanup
- Yeast (if present) will continue to drop out of suspension

 

There were some lengthy and very useful explanations of what goes on in beer when it ages in the old forums, but those are all lost in the ether, sadly. But here's a link I bookmarked from one of those posts http://beersensoryscience.wordpress.com/2010/11/15/chemistry-of-beer-aging/

 

From my limited experience the alcohol "bite" tends to fade in some high alcohol content beers over time. That's the main benefit I like.

 

One of the reasons that the "bite" often fades (in my understanding) is that certain other alcohols that are present in very small quantities and are products of normal fermentation degrade over time in the bottle, thus taking away the "heat" aspect of the flavor that they can contribute. These alcohols can be deadly if concentrated, hence the warnings about distilling homebrew or any beer for that matter without the proper testing equipment.

 

Pretty sure James is partly right, I just bottled my first homebrew and it needs bottle conditioning so you put in extra sugars and the leftover yeast consumes this, creating CO2 and also changing the flavor over time. How long this can go on for, I'm not sure but you're right that only something like Brett can develop indefinitely as it ages.

 

Magic.

 

A whole lot of chemical reactions.

 

Here's a link to the original article for those of you at universities and in industry with access to ScienceDirect..

One of the things I often wonder is if there is an optimal set of conditions to age gueuze at to maximize the funky / cheese rind charecter found in older bottles... is this age alone or a charecteristic of the individual batch?