What can cause color loss in a finished beer?

I made an American Brown ale that turned out very dark brown.

I opened the last couple of bottles a month or so apart after most of the batch.

The color seems to have faded to a significantly lighter shade of brown,

still in the brown ale normal range but different enough from the fresh beer to confuse me.

What can possibly cause this phenomenon?



RECIPE:

Based on:

https://www.brewersfriend.com/homebrew/recipe/view/784491/brown-ale-chance-dodds

Title: Brown Ale

Brew Method: BIAB

Style Name: American Brown Ale

Boil Time: 60 min

Batch Size: 11 liters (fermentor volume)

Boil Size: 17 liters

Boil Gravity: 1.031

Efficiency: 60% (brew house)

No Chill: 20 minute extended hop boil time

STATS:

Original Gravity: 1.049

Final Gravity: 1.010

ABV (standard): 5.12%

IBU (tinseth): 32.19

SRM (morey): 19.59

Mash pH: 0



FERMENTABLES:

2.5 kg - Pilsner (87.7%)

200 g - CaraMunich II (7%)

100 g - De-Husked Caraf II (3.5%)

50 g - Melanoidin (1.8%)

HOPS:

5 g - Magnum, Type: Pellet, AA: 15, Use: Boil for 40 min, IBU: 20.44

5 g - Ekuanot, Type: Pellet, AA: 14.25, Use: Boil for 0 min, IBU: 11.76

25 g - Ekuanot, Type: Pellet, AA: 14.25, Use: Dry Hop for 5 days



MASH GUIDELINES:

1) Infusion, Temp: 68 C, Time: 45 min, Amount: 17 L



OTHER INGREDIENTS:

1 tsp - Irish moss, Time: 10 min, Type: Water Agt, Use: Boil

YEAST:

Fermentis / Safale - American Ale Yeast US-05

Starter: No

Form: Dry

Fermentation Temp: 18 C

Pitch Rate: 0.75 (M cells / ml / deg P)



PRIMING:

CO2 Level: 2.52 Volumes



Generated by Brewer's Friend - https://www.brewersfriend.com/ Date: 2019-12-18 10:39 UTC Recipe Last Updated: 2019-09-30 16:12 UTC

Topic color aging homebrew

Category Mac


I've been brewing for 10+ years so the answer I give will be based upon experience. I have often seen beer to lighten in colour to some extent and have generally attributed this to the settling of sediments and proteins from the beer during the conditioning phase. With less sediment in suspension, light can more easily pass through the liquid, making it appear lighter in colour.

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