Reusing yeast,how long can this go on?

[Brewmeistermj]

I have read a few posts about reusing yeast. Nobody seems to have a clear definition as to how many times you can repitch it. I would like to share my method and welcome any comments positive or negative. I have been reusing Wyeast 1084 dated Nov 8 2004 for five years now. I brew stout.This is my process.
I pitch my yeast when my wort has cooled to 68F
I ferment at basement temp(65F) about a week.
I then rack and "lager" at 34F another few days until the yeast settles out.
I save the dregs and store them in an airlocked wine bottle at 34F
I repitch them in my next brew,always within 3 weeks.
I have done this around 70 times and my yeast is still very strong. I have fermented from 1.040 to 1.078 (my strongest)with short lag and fast fermentation time. I have never washed it. My beer turns out good and I have noticed no changes in flavor. I served some yesterday and got good compliments. I have no ego and will always do what's best for my beer. I will change my process if I need to.

 

[boo boo]

As long as you have no flavour or fermentation issues, then use it as long as you want.

You have used it a lot longer than anyone I know of already.

 

[pdbreen]

If you like the results, keep doing what you're doing! The generational risk is not so much that the yeast won't ferment the wort, but that the purity of the original strain will become diluted or change over time. But - that change could be something you like even better!

 

[Scooby_Brew]

I have done this around 70 times and my yeast is still very strong. I have fermented from 1.040 to 1.078 (my strongest)with short lag and fast fermentation time. I have never washed it.

I reuse unwashed yeast for 3 years now and I got 1 infection so far at 9th generation from the start. I brew 10 gal batches, so I can get 16 5-gal Corneys full of ale from one packet of yeast, if I only go 8 "generations deep" After about 8th generation of yeast I start all over again with new yeast.

 

[mordantly]

unless im mistaken, yeast procreates asexually and makes a direct copy of itself. so contamination is most likely the sole factor limiting reuse, provided you didnt use the yeast to ferment a sake.

 

[Brewmeistermj]

I reuse unwashed yeast for 3 years now and I got 1 infection so far at 9th generation from the start. I brew 10 gal batches, so I can get 16 5-gal Corneys full of ale from one packet of yeast, if I only go 8 "generations deep" After about 8th generation of yeast I start all over again with new yeast.

I also brew 10 gallon batches. Was your infected brew caused by your yeast or could it be some other factor?

 

[Dauntless]

Way to kick it Oldschool.

 

[Scooby_Brew]

I also brew 10 gallon batches. Was your infected brew caused by your yeast or could it be some other factor?

I think the infection happened somewhere down the road caused by some other factor, but reusing old yeast helps spread it and grow in to the new batch. That's the biggest risk from reusing slurries.

I like to use only half of the slurry or less (1/3) from the old batch into the new batch, so this way the yeast gets a chance to multiply before eating sugars, I think it makes for a healthier yeast that way.

I also collect the slurry into a jar and keep it in the fridge for a couple of weeks if necessary.