How many times should I re-pitch the same yeast?

[Kirkwooder]

It occurred to me that I have saved and re-pitched the same US-05 yeast at least a dozen times. I have not yet noticed any off flavors or other issues. When should I stop re-pitching?
Is there a magic # of ferment cycles that a single package of yeast should be used for?

 

[brownni5]

Most would say you've surpassed it, but if it's still working for you, then why change?

 

[skw]

Not directly repitching, but I've stretched a pack of Wy 1217 over three years by overbuilding starters. I'm not noticing any off flavors, however I feel like it doesn't flocculate as well as it used to. I'm tempted to get a new pack just to see how it compares, then carry on with my own culture to see where it takes me.

 

[LLBeanJ]

It occurred to me that I have saved and re-pitched the same US-05 yeast at least a dozen times. I have not yet noticed any off flavors or other issues. When should I stop re-pitching?
Is there a magic # of ferment cycles that a single package of yeast should be used for?

No magic number. You can keep using it until it is no longer meeting your expectations or you are not happy with the results.

 

[kh54s10]

Most often # of times I have seen recommended are between 5 and 10. The yeast (I believe) will mutate. How many re-pitches that takes probably depends on many factors. If it is kept free of contaminates you could go much longer than if something was introduced.

Wondering?? Could a mutation caused by repeated re-pitches make the yeast produce something even better??

I guess that you would be the first to know, at least for your particular batch of yeast.

 

[skw]

Could a mutation caused by repeated re-pitches make the yeast produce something even better?

For us home brewers, a likely yeast mutation, unfortunately, is petite mutation.

My guess would be that if you intend to get your own "house" yeast by reusing and selecting, you should streak on agar plates and regrow from single cells from time to time in order to avoid contamination and maintain a high percentage of young cells.