aging's affect on bitterness

after a beer has hit its target FG, how does aging the beer affect bitterness? two things i am interested in; the science of what is going on during aging, two, how much can one expect bitterness to "decrease" during aging? (i imagine there are a myriad of factors here).

example:
i brewed an american citrus wheat recently, 14 days in primary... now sitting in a keg at its target FG (1.007). when i pulled a sample for my gravity reading i tasted the sample and it was still quite bitter. with this type of beer, what can i expect to happen in another month for instance?

here is the recipe that i followed:



American Citrus Wheat

From the BrewBlog of wilcox
, michigan USA
Printed December 17, 2008
Specifics
Style: American Wheat or Rye Beer
Yield: 5.00 gallons
Color: 6.4 SRM
Bitterness: 20.4 IBU

OG: 1.052
General Information
Method: Extract
Recipe
Extracts
5.00 pounds LME - Wheat 90.9% of grist
5.00 pounds Total Extract Weight 90.9% of grist
Grains
0.50 pounds American Dextrin (Cara-Pils) Malt 9.1% of grist
0.50 pounds Total Grain Weight 9.1% of grist
Adjuncts
1.00 pounds Honey (Clover)
Miscellaneous Ingredients (Non-Fermentable)
3.0 ounzes Lemon Zest @ 15 minutes (Boil)
1.5 ounces Orange Zest (Peel) @ 20 minutes (Boil)
Hops
0.50 ounces Cascade 6.3% Pellets @ 15 minutes
Type: Aroma
Use: Boil 3.2 AAUs
0.33 ounces Nugget 11.50% Pellets @ 60 minutes
Type: Bittering
Use: Boil 3.8 AAUs
0.83 ounces Total Hop Weight 6.9 AAUs
Yeast
WYEAST 1056 - American — Liquid — 125 mls

Fermentation
Primary: 14 days @ 70° F
Secondary: current @ 65° F
BJCP Style Info
Style: American Wheat or Rye Beer
O.G.: 1.040 - 1.055
F.G.: 1.008 - 1.013
ABV: 4.0 - 5.5%
Bitterness: 15 - 30 IBUs
Color: 03 - 06 SRM

I'm surprised bitterness is an issue with so few hops. I mean you only used 1/3 an ounce of nugget. Sure Nugget might be considered a bit high for a wheat brew but its only a 1/3 of an ounce. So I guess I don't know nearly as much as I thought.

Sadly I don't know much at all about kegging. I do know that had you bottled that there is a world of difference between the taste of beer at bottling time and 3+ weeks later. Even for a wheat.

williec30 said:

after a beer has hit its target FG, how does aging the beer affect bitterness? two things i am interested in; the science of what is going on during aging, two, how much can one expect bitterness to "decrease" during aging? (i imagine there are a myriad of factors here).

Click to expand...

bump on this... can anyone explain this to me?

Bittering is the last thing to go. I'm surprised you are finding the brew overly bitter, since it is at the low end for the style. Did you use orange zest or peel? The peel can be extremely bitter.

Most beers start out fairly fruity and then get more bitter with age. The bitterness you are experiencing may be due to hot side aeration due to splashing of the wort before the temperature gets below 85F. Adding oxygen to the wort at temps above 85F tends to oxidize the tannins and melanoidins in it making the beer taste bitter.

If it's any conciliation, the first batch I ever brewed was undrinkable for the very same reason.

Tom

Bitterness will mellow with age, but there are a couple things I noticed here that may be influencing this bitterness. First, the beer is quite young at only 2 weeks, so it may still be green, let it sit in the keg for another 2 - 3 weeks before making any final judgment.

There are a couple items in your recipe that I would point out as well...

Miscellaneous Ingredients (Non-Fermentable)
3.0 ounzes Lemon Zest @ 15 minutes (Boil)
1.5 ounces Orange Zest (Peel) @ 20 minutes (Boil)

The only part of the rind that you want is the oil contained in the colored outer rind - you should use a zester or microplane to remove it. The white part of the rind is extremely bitter and unpleasantly so - I mention this specifically because you list (Peel) after the orange zest - you definitely don't want to just peel an orange and toss the entire rind in.

You also list that you boiled these ingredients for 15 - 20 minutes. You should be adding the zest at the very end of the boil (5 - 0 minutes), during the ferment, or add the zest to some vodka for a week or two before bottling/kegging and then strain and add the extract to the bottling bucket or keg.

But...before you do anything, let it sit for another 2 - 3 weeks to mellow the flavors.

Good luck,
Chris