Quote:
Originally Posted by kyleobie
I've wondered something along this line for the expensive liquid yeasts - if you wash it and save it for a couple months, do you get the same results as if you had just bought it the same day?
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Yes and No. You can get the same results, but you may have to adjust the amount of yeast you use. I'll explain my take on it:
Same results can be had after a few months. But yeast will die. The more dead yeast in a brew the worse the beer will be, in theory. Most homebrewers won't experience this though. So it's not a real issue.
The bigger problem is yeast viability, and the effect it can have on your pitch rate. The % of yeast that are viable will be less, for sure, over any period of time. Therefore, your results won't be the same unless you account for this and pitch more. The pitch calculator at
Mr Malty, for example, takes this into account.
I think a good rule of thumb is to limit repitching to about 6 batches to prevent too much dead yeast from entering your beer. And if you are storing washed yeast, you might limit it from 6 months to a year. It can lose viability by that point.
But there is no hard and fast rule. Generally speaking, if you get in the neighbourhood with the pitch rate, and there is no infection, you should be ok for quite a while.