How long can you reuse your yeast

[i4ourgot]

I was just wondering how many batches of beer you can brew with yeast? What happens with each progressive batch and what will be the effects on your beer.

 

[duboman]

I was just wondering how many batches of beer you can brew with yeast? What happens with each progressive batch and what will be the effects on your beer.

i will go 4-6 generations and then go fresh. There is always a certain risk of mutation occurring from one batch to another unless you're making slants, of course this is strictly my opinion

 

[LLBeanJ]

Well, like most questions in life, the answer is... it depends.

Are we talking about washed yeast, yeast that was saved off a starter, direct pitching of slurry, slurry with a starter, or something else? How anal are you about sanitation? The general rules of thumb regarding yeast that was actually used to ferment a batch before it was harvested, then washed, is 5-10 generations. Unwashed slurry is maybe 3-5 generations and I believe may be more prone to infection than working with washed yeast.

Yeast that was split from a starter and saved for a later starter (lather, rinse, repeat) can theoretically be used indefinitely if good sanitation techniques are practiced, though petite mutation is still likely to occur over time. This is the method I use and would keep reusing the yeast until it develops a flavor/character I don't care for.

 

[SavoryChef]

My local brewpub goes 10 generations. They buy enough for a 7 barrel system then send it off to the other locations which is a 25 and a 30 barrel.

 

[Black]

I always reuse my unwashed yeast slurry 3-5 times and I honestly can't tell the difference.

I agree that properly washed yeast could be used indefinitely. However, given the low cost of new yeast, IMHO it's not worth the trouble, unless it is a very special strain you want to keep. But then again, we're homebrewers so I would understand someone going the extra mile to propagate his yeast.


Cheers !

 

[i4ourgot]

Dang I thought yeast was pretty expensive and the more I can reuse it the more I will save, plus I also get pretty much instant fermentation once I pitch it into my wort.

 

[Black]

Dang I thought yeast was pretty expensive and the more I can reuse it the more I will save, plus I also get pretty much instant fermentation once I pitch it into my wort.

Well, I find that 6$ for 3-5 batches is really cheap. Under a buck per 6 gallons.. spread that cost on 70 bottles.

How much do you pay for your yeast?

BTW, if you let your slurry warm to room temp for a few hours (while you're brewing) and pitch it while it's healthy, you will get fermentation going very quickly. I always had very good results with yeast slurry up to a month old. I even used a 2 months old one with the same success, although I try to avoid it.

Cheers !

 

[Calder]

The general rules of thumb regarding yeast that was actually used to ferment a batch before it was harvested, then washed, is 5-10 generations. Unwashed slurry is maybe 3-5 generations and I believe may be more prone to infection than working with washed yeast.

Washed or un-washed shouldn't make any difference in the viability or mutation of the yeast. It could even be argued that washing gives a greater chance of contamination (more exposure/opportunity, and no alcohol to protect it).


For the OP:

Yeast can be re-used as many times as you want. Practice decent sanitary measures and you could use it every couple of weeks for years.

Now the yeast will change with repeated use, how you handle it and when you harvest it can greatly affect how it mutates over time.

General rule of thumb is 5 beers before you will notice any obvious change, but it could be many more than that.

To get it to last as long as possible, ensure you pitch the correct amount each time and not just put the next beer on the cake of the last one.

 

[msa8967]

You will also need to think about the style, color and gravity of the beers you are brewing with each generation. I have read in many past replies that it is far more successful to go from lighter to darker, lower gravity to higher gravity, lower IBU's to higher IBU's than in any of the reverse of these processes. Staying within the same style is not a prblem but reusing the yeast from a baltic porter to make a blonde ale might not be the best use for the washed yeast.

 

[william_shakes_beer]

I harvest yeast from starters and have successfully made a new starter from a sample that was harvested 6 months prior. The yeast is viable untill the slurrey at the bottom of the tube is the color of peanut butter. I periodically review my samples and stir up a fresh starter for any samples that are getting a bit dark.