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Why is oxygen important?
Oxygen has both positives and negatives when it comes to brewing and beerâ¦
Positives â itâs needed for yeast growth during fermentation. The right amount will help strong, healthy yeast cells to form and that means good fermentation and consistent beer with no âoffâ tastes.
If youâre wanting to bottle-condition your finished beer or do likewise in any other sort of container, then a small amount of oxygen will help the secondary fermentation in pretty much the same way.
Negatives â At any time after fermentation, high levels of oxygen are likely to cause problems. Generally that can be for taste or appearance. Oxidised beer if often described as tasting âcardboardyâ and oxygen can increase the likelihood of haze formation when the beerâs being stored.
What sorts of levels are good?
Typically around 10-12mg/l (ppm â parts per million) is ideal for fermentation. Many big UK brewers tend to over oxygenate, up to 20mg/l to speed up yeast growth and make the fermentation stage that bit faster, but this isnât really necessary.
These days major brewers and packaging companies are looking to keep oxygen levels down below 10-20ug/l (ppb â parts per billion). The âdelicateâ taste of many keg/can lagers means the slightest oxidation will show as a taste defect.
Higher levels can be tolerated by more ârobustâ beers, but itâs always good to try and keep things as low as possible!
Where is important and why?
As weâve said, the first important place to know how much oxygen you have is when youâre adding yeast to wort. Yeast needs oxygen to grow and multiply, just as it needs the sugars from your malt. Too little oxygen and yeast growth will be poor, meaning slow fermentation; too much and the opposite can happen, your fermentation goes too fast. Both situations end with beer that doesnât taste like you wanted.
If your brewing equipment allows, you can control the amount of oxygen you have in your fermenter by aerating the wort. This needs sterile air, a pressure regulator, some pressure tubing and a fine jet or sinter to make tiny bubbles (these dissolve better).
On a smaller scale, stirring or shaking will work almost as well.
After fermentation is complete, all the oxygen should have been used, so making sure it stays low will help keep that beer in good shape!
- If you transfer from fermenter to maturation, you want to be sure any pipes, pumps or other equipment arenât allowing oxygen in;
- If you filter into bright tank, again keeping dissolved oxygen levels as low as possible helps your beer to maintain condition and taste;
- In package â cask, keg, bottle or can â careful handling ensures your beer reaches the consumer bright, clear and tasting fresh.
At any of these post-fermentation stages, high oxygen levels cause two major problems â taste defects and haze:
- Typical taste problems caused by high dissolved oxygen levels are stale, âpaper/cardboardâ flavours on finished beer.
- Age-related haze and chill-haze are both adversely affected by oxygen, which increases the formation of visible haze compounds.
Cheers! :
Oxygen has both positives and negatives when it comes to brewing and beerâ¦
Positives â itâs needed for yeast growth during fermentation. The right amount will help strong, healthy yeast cells to form and that means good fermentation and consistent beer with no âoffâ tastes.
If youâre wanting to bottle-condition your finished beer or do likewise in any other sort of container, then a small amount of oxygen will help the secondary fermentation in pretty much the same way.
Negatives â At any time after fermentation, high levels of oxygen are likely to cause problems. Generally that can be for taste or appearance. Oxidised beer if often described as tasting âcardboardyâ and oxygen can increase the likelihood of haze formation when the beerâs being stored.
What sorts of levels are good?
Typically around 10-12mg/l (ppm â parts per million) is ideal for fermentation. Many big UK brewers tend to over oxygenate, up to 20mg/l to speed up yeast growth and make the fermentation stage that bit faster, but this isnât really necessary.
These days major brewers and packaging companies are looking to keep oxygen levels down below 10-20ug/l (ppb â parts per billion). The âdelicateâ taste of many keg/can lagers means the slightest oxidation will show as a taste defect.
Higher levels can be tolerated by more ârobustâ beers, but itâs always good to try and keep things as low as possible!
Where is important and why?
As weâve said, the first important place to know how much oxygen you have is when youâre adding yeast to wort. Yeast needs oxygen to grow and multiply, just as it needs the sugars from your malt. Too little oxygen and yeast growth will be poor, meaning slow fermentation; too much and the opposite can happen, your fermentation goes too fast. Both situations end with beer that doesnât taste like you wanted.
If your brewing equipment allows, you can control the amount of oxygen you have in your fermenter by aerating the wort. This needs sterile air, a pressure regulator, some pressure tubing and a fine jet or sinter to make tiny bubbles (these dissolve better).
On a smaller scale, stirring or shaking will work almost as well.
After fermentation is complete, all the oxygen should have been used, so making sure it stays low will help keep that beer in good shape!
- If you transfer from fermenter to maturation, you want to be sure any pipes, pumps or other equipment arenât allowing oxygen in;
- If you filter into bright tank, again keeping dissolved oxygen levels as low as possible helps your beer to maintain condition and taste;
- In package â cask, keg, bottle or can â careful handling ensures your beer reaches the consumer bright, clear and tasting fresh.
At any of these post-fermentation stages, high oxygen levels cause two major problems â taste defects and haze:
- Typical taste problems caused by high dissolved oxygen levels are stale, âpaper/cardboardâ flavours on finished beer.
- Age-related haze and chill-haze are both adversely affected by oxygen, which increases the formation of visible haze compounds.
Cheers! :
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