It’s not just about saving money… re-using yeast has been done for thousands of years… and it could be what kicks up the quality of your beer to the next level…

I’ve written about this in the past… if you haven’t tried it, I recommend you take the yeast from your next batch and use it for the next one…

… but before you do, here’s a few rules…

I got a comment on my YouTube channel about re-using yeast… more specifically about storing yeast…

In the book Yeast by Chris White and Jamil Zainasheff, they mention that yeast should be used within 2 weeks after fermentation is done… after that, the yeast should be frozen and stored in strictly sanitary conditions…

The comment on my YouTube video said that they’ve stored yeast for up to 2 months… and all they did was make a yeast starter before using that yeast…

Nothing wrong with that…

What I believe Chris and Jamil are saying is that, if you use the yeast within 2 weeks of fermentation there is no need to make a yeast starter… you can pitch directly and the yeast will be strong enough to ferment the beer as if you pitched from a starter…

Storing yeast? In the book Brew Like A Monk by Stan Hieronymus, a Belgian brewer mentions that yeast can survive up to six months in a bottle and brewers can cultivate that yeast and re-use it… I’ve personally never stored yeast longer than 2 weeks…

So what is the difference between fresh yeast from a vial and re-using yeast?

What I have noticed from re-using yeast is that fermentation is usually stronger when I re-use yeast… Lag time is shorter and if I’m using clean yeast strains, fermentations are cleaner…

The way I think of it is that yeast fresh out of a vial are like rookies… they have no experience and while it may be as viable as it gets, many yeast cells are too weak to ferment strong… when you re-use yeast, the cells are stronger and ‘experienced’… batch 3-5 are about as good as it gets… after that, the amount of bacteria starts to become noticeable and you must either wash your yeast or start out with a new vial…

Personally I’ve only gone up to 4 batches, so I don’t know how bad it gets if you re-use yeast more than that… I’ve heard breweries re-use yeast up to 7-10 times… maybe that will be my experiment after this decoction mash experiment… how many times can you re-use yeast before you notice negative effects?

Here’s the last thing I want to cover today… how should you plan your brews when re-using yeast…

Everytime you brew beer, the yeast adapt to the type of beer and tend to develop characteristics based on the beers they ferment… So therefore it’s recommended that you plan your beers so the next batch is not affected by the previous one…

That means you should brew a lighter beer first and move up to darker beers when re-using yeast… low alcohol to high alcohol, and less bitter to more bitter beers…

I have yet to see the effects of re-using yeast from a darker, higher alcohol or bitter beer in a lighter, lower alcohol or less bitter beer… I’ll be chalking that as an experiment as well… until then here’s my plan…

Today, I’ll be brewing a Munich Helles followed by a Munich Dunkel, then a Vienna or Marzen beer and finally a Schwarzbier…. So look for a video next week…

What can you share about re-using yeast?

Cheers!

P.S. I really wanted to brew this last weekend and share a video, but I ended up running a 5k (Color Run) with my friend Susie to raise money for the Cardon Children’s Medical Center at Banner Health… I’m sure you’ll forgive me for starting my experiment a week late …