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I was amazed at how much better my home brews are getting from just leaving them be? Why is that? How exactly can the flavour of beer improve by just leaving it alone in a non-reactive container? I would love to learn the science behind this phenomenon.

I started with a kg of oats. I decided I wanted to know what coco powder would do in beer? I also thought I would like to know what a few coffee grains would do. So I added them.

I only did a 45 minute boil no hops. I usually do an hour but simply put the African heat got to me. I used an ice bath this time and after adding the yeast I left it over night.

The next day I tried some before I went to bottle but was somewhat disappointed. The coco made it extremely bitter. I also realised that the coco powder I used was a energy type of drink.

This meant it had a whole list of minerals in. This seemed to me to add a very harsh bitter taste to it. I was almost ready to consider the experiment a failure but to my surprise I tried some today and the harshness seemed to mellow out a great deal. Also the taste of the oats is now much more prominent.

It was amazing to me how big of a difference one day could make. I'm tempted to leave it for a week.

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    What type of brewing process do you use and what type of beers? – Philippe Nov 11 '15 at 12:21
  • I'll add some more details to what exactly I did. – Neil Meyer Nov 11 '15 at 14:27
  • Bottled straight after boiling/cooling? It's this an alcoholic beer? Are you fermenting it? – Cleber Goncalves Nov 13 '15 at 0:27
  • OK sorry my bad it has yeast added and stands over night. Will edit. – Neil Meyer Nov 13 '15 at 5:56
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When its really fresh its still a sum of its parts. Water, yeast, malt and hops. In time the flavors marry and it becomes beer. I know that sounds hokey but its the exact same thing as simmering soup. At first its just water, vegetables meat and salt. But after a long simmer its something better.

Scientifically, who knows whats really going on chemically, but certainly compounds are combining to make new ones.

In beer another thing is physical settling. As it sits there are inert particles from the grain, hops and yeast that take time to settle out to the bottom of the bottle or keg. These things may not taste bad but they may mask other less subtle flavors.

Lastly, the reactivity of the container has nothing to do with it. It literally is the many components slowing coming into a single thing.

Ask any chef or cook and they will tell you the same thing. Its not a scientific answer, but its real.

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    Two things: You forgot the other part; Adjuncts. I find that spices usually need a few months to settle down. The other thing: All beers get better with age, BUT the time is different for different styles. An IPA is usually best between a month and three months from brewing. An RIS can do with about a year of aging. The biggest problem with aging is not drinking the beer. :p – Atron Seige Nov 12 '15 at 6:40
  • I know this isn't beer, but wine style meads can take up to 2 years before they taste any good. – Escoce Nov 13 '15 at 17:26
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When leaving the brew as you are not filtering or pasteurising there will be some yeast leaf in suspension, some of these will continue to clean up by products for a week or 2 after the have completed the majority of their fermentation work.

The general trends when your beer ages are that it will lose bitterness, the sweet flavour (toffee-like) and aroma with increase, and the flavour of blackcurrant leaves (ribes) will peak then diminish. (Dalgliesh 1977).

Sometimes when beer ages it takes on a cardboard flavour (E)-2-nonenal, this if formed by the oxidation of lipids [1].

Degradation of alpha and beta acids from the hops evolves the flavour profile[2], depends what you are looking for in a beer to know if this is desired. If you have a darker beer then the products of Millards (melanodins[3]) evolve over time and can lead to the matured port like flavours you get in many aged dark beers.

There are myriad chemical reaction occurring in aging beer due to this fact the temperature at which the beer is stored affects the reactions that take place due to the differing activation energies of the reactions. For example Lager aged at 25C tends to develop more caramel character, but >30C, cardboard dominants[1].

I will expand this answer a later, I have a few more papers on the subject. And will try and dig out links to the copies not trapped behind paywalls.

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