An Accidental 7-Year Brewing Experiment - Metabisulfites in Long-Aged Beers
Channel: Sui Generis Brewing
Date: 2022-03-12

A while ago I set out on a 2 year project to investigate the effect of metabisulfite on the aging characteristics of long-aged beers...and 7 years later finally finished the project. This video is a deep-dive into what I discovered, covering everything from the science behind the flavour changes that take place as beers age, the role of oxidation in this process, how beer oxidizes, how metabisulfite counteracts oxidation, and of course the results of my experiment on the impact of metabisulfite on the aging of a barley wine over seven years.

The keen of eye may notice that not all of the chemical equations balance out in the video. This is not a mistake - to simplify things intermediary steps and reactants have been left out in many places.

This is a long video, so I've broken it down into several chapters. Please skip ahead to the parts that interest you:
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CHAPTERS:
Intro – 0:00
What this experiment is about – 0:56
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THE SCIENCE:
What happens during aging – 1:36
Metabisulfites & pH – 3:36
Metabisulfite in Beer (Theory) – 5:05
The Chemistry of Oxidation – 6:56
How Metabisulfite Works – 14:20
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THE EXPERIMENTS:
Concept – 17:08
Design – 17:50 
Results – 22:30
Conclusions – 25:22
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For those who are interested, Brülosophy has done a lot of investigation of metabisulfite on shorter time periods. The posts I refer to in the video are:
https://brulosophy.com/2019/09/23/cold-side-oxidation-impact-of-dosing-beer-with-sodium-metabisulfite-smb-at-packaging-exbeeriment-results/

https://brulosophy.com/2022/02/07/exbeeriment-impact-adding-potassium-metabisulfite-pmb-at-dry-hop-has-on-an-american-pale-ale/