Brewer’s yeast: 9 things you need to know

Here are the top things every brewer should know about yeast, this mysterious and even magical microorganism. Historians suggest that the ancient Egyptian civilizations over 5,000 years ago were using yeast and the process of fermentation to produce alcoholic beverages.

How long does dry yeast last

Theoretically, dried yeast can be stored indefinitely. 2 years is the standard shelf life from most manufacturers as long as the yeast is stored properly. In reality, dry yeast is good far beyond its “best before” date. If you are using an old yeast make sure to rehydrate the yeast and make a starter prior to pitching.

How long can liquid yeast be stored

What happens to liquid yeast is that when once all of its food is gone the yeast goes into a state of dormancy. However, and the viability of the yeast will be reduced when times goes by.

6 months is the standard shelf life as long as the yeast is stored properly. It’s a good idea to make a starter prior to pitching if you plan on keeping a yeast culture for a longer period of time.

Type of yeastUnrefrigeratedRefrigeratedFrozenOpened
Dry12 months18 months2 years+4-6 months
Liquid2-3 weeks6 months~1-4 weeks

Can you use brewing yeast for bread

Brewers yeast are more like sourdough than normal bakers yeast. Sourdough yeast takes a long time to rise bread (between 6 and 12 hours) so account for a longer baking session. Most people that have a bad experience with brewing yeast do not give the bread time to rise resulting in a heavier or denser bread.

Can you freeze brewing yeast

Yes you can freeze yeast to store it for a longer time period. To stop the ice-crystals to destory the yeast cells an antigreeze agent like food grade glycerol is mixed with the yeast slurry to a 20-25% solution. Stopping the freezer from doingin thermal cycling “defrosting” cycler will increase the viabilty of long therm storage of yeast.

Will freezing hurt liquid yeast

Freezing liquid yeast without any antifreeze agent like glycerol will create ice-crystals that destroys the yeast cells drastically impacting the viability of the yeast.

How to freeze yeast with glycerol

The conventional wisdom seems to be that using glycerin as a cryoprotectant in a ~25% solution is the best way to do things in a home freezer. Glycerin, glycerine and glycerol are all the same thing. If I understand correctly, the cold temperature slows down the yeast’s metabolism significantly, and the glycerin prevents ice crystals that form in the suspension from tearing the yeast to bits.

Should you stir yeast when brewing beer?

There is no significant difference between stirring a dry yeast pack or sprinkling it on top. When the yeast is dry its in a dormant state. It takes time for it to rehydrate and become active, the difference between sprinkling it on top and the amount of time it takes it to rehydrate and become active by you stirring it up is negligible.

The benefit of stirring the yeast is will only be that you are aerating the worth introducing more oxygen that will help with the cell growth. When oxygen is present yeast cells will consume the oxygen and multiply into more yeast cells.

Should I stir beer during fermentation?

Do NOT stir the beer during fermentation. Stirring it will risk that you oxygenating the wort. As oxygen is a reactive molecule, even in very small quantities is bad for a finished beer. It will affect taste compounds like hop favours resulting in a stale taste and weird off flavours.

Should you stir homebrew before bottling?

Do NOT stir the brew before bottling, on top of risking oxygenating the wort you’ll only end up with all the bottles being incredibly yeasty. After a time the yeast sediment will settle out in the bottle, it will just take longer and have more yeast than normal.

What happens if you bottle beer too early?

If you bottle before the yeast has finished and there is still sugars to ferment in the wort you will be risking gushing beers or even worse bottle bombs. When doing natural carbonation you calculate the sugar needed to get the correct CO2 level in the finished bottle. If there are still unaccounted sugars present in the beer the risk is that the bottle will be over-carbonated and risking exploding.

A normal beer bottle can hold up to 3 atm (45 psi), and “champagne” bottles can hold up to 6 atm (90 psi) (Welshcider). It’s still recommended to be on the safe side as the bottles can have a lower breaking point depending on grade.