I’ve read that reusing yeast past 5 generations is not recommended, but has anyone had any ill effects of going past 5?
I’ve read that bread bakers who use sourdough starters feed their starters either everyday or every week, and the starter can practically live forever. The way they feed it is by throwing away half of the starter, then feed it so that it doubles in volume. Then you take a portion of that and use it to make bread. Would this method also work for beer yeast?
The companies that sell yeast grow it that way, and there is no actual limit to how long you can keep a strain of yeast going. The risk though is that the yeast will evolve over time into a strain that doesn’t have the same characteristics as it started with. The companies have stringent quality control checks to make sure that the cells they feed to propagate match what they want. Most homebrewers don’t have the knowledge or equipment to do that.
I will rarely use a package of yeast for just one batch, and have gone to 7 or 8 generations on occasion. But I take a break from brewing in the summer and I’ve found it doesn’t really make sense to try and revive a strain after a long storage.
[quote=“rebuiltcellars”]The companies that sell yeast grow it that way, and there is no actual limit to how long you can keep a strain of yeast going. The risk though is that the yeast will evolve over time into a strain that doesn’t have the same characteristics as it started with. The companies have stringent quality control checks to make sure that the cells they feed to propagate match what they want. Most homebrewers don’t have the knowledge or equipment to do that.
I will rarely use a package of yeast for just one batch, and have gone to 7 or 8 generations on occasion. But I take a break from brewing in the summer and I’ve found it doesn’t really make sense to try and revive a strain after a long storage.[/quote]
Have you noticed a difference in taste from using a 7th or 8th generation yeast strain?
+1
That goes for not only packaged yeast (such as Wyeast, WhiteLabs, ECY, etc) but also when I build up a pitchable amount of my nearly 30 year old house yeast.
7 generations of repitching (with no rinsing or washing of the slurry) is routine for me nowadays with any yeast. At one time, I was routinely going well beyond 12 repitches (with no negative issues, but I finally decided not to tempt the gods anymore).
Happily, I’ve never experienced any viability issues doing this, nor have I ever experienced any issues with off flavors attributable to the repitching. It’s really just all about keeping tabs on one’s brewing practices, and fanatical attention to sanitation (which should always be job#1 anyway).
[quote=“maltybeer”][quote=“rebuiltcellars”]The companies that sell yeast grow it that way, and there is no actual limit to how long you can keep a strain of yeast going. The risk though is that the yeast will evolve over time into a strain that doesn’t have the same characteristics as it started with. The companies have stringent quality control checks to make sure that the cells they feed to propagate match what they want. Most homebrewers don’t have the knowledge or equipment to do that.
I will rarely use a package of yeast for just one batch, and have gone to 7 or 8 generations on occasion. But I take a break from brewing in the summer and I’ve found it doesn’t really make sense to try and revive a strain after a long storage.[/quote]
Have you noticed a difference in taste from using a 7th or 8th generation yeast strain?[/quote]
No, never noticed a taste difference. I did notice differences in the fermentation dynamics. In general, they tended to improve over the first few generations and then stay there.
I also noticed some situation specific changes. If I oxygenated properly, I would notice that the next time I pitched the yeast (beer after the one with good oxygenation) the yeast would take off much more strongly than if I was lazy about adding oxygen on the brew before, and the effect seemed to increase with more generations. I also noticed a change in flocculation during the time I was experimenting with washing my yeast, with the yeast getting harder to clear over a couple of generations. I guess however I was doing it, I was selecting for less flocculent cells.
+1
That goes for not only packaged yeast (such as Wyeast, WhiteLabs, ECY, etc) but also when I build up a pitchable amount of my nearly 30 year old house yeast.
7 generations of repitching (with no rinsing or washing of the slurry) is routine for me nowadays with any yeast. At one time, I was routinely going well beyond 12 repitches (with no negative issues, but I finally decided not to tempt the gods anymore).
Happily, I’ve never experienced any viability issues doing this, nor have I ever experienced any issues with off flavors attributable to the repitching. It’s really just all about keeping tabs on one’s brewing practices, and fanatical attention to sanitation (which should always be job#1 anyway).[/quote]
You have a 30 year old house yeast?
I do. It’s a long story, but briefly, the original sample (unknown pedigree) was given to me sometime around '84 or '85. It was the first time I ever brewed with “wet” yeast…in fact I was even still a full year away from brewing all grain. I liked the results a lot (clearly better than any dry yeast around at the time), so I just kept reusing it since no one said I shouldn’t. Eventually with some help I plated it out and made slants and have periodically built it up and brewed with it ever since. Interesting thing is that it had already gone through a few generations of brews before the original sample was even given to me.
I do brew with other strains too (WY1968, 1098, 1099, ECY “Old Newark”) and always take those through multiple generations as well…but I also make sure to get in a string of brews each year using the ‘old reliable’.
I think the furthest I have taken a yeast is 22 generations. I add yeast nutrient to the boil with those yeasts and oxygenate like crazy to max out O2 with a mixstir rod (like 3-4 minutes at full blast with a drill - that is to the point where no greater O2 can be introduced with this method). But I don’t have a thirty year old on hand!
We could all benefit more one or more 30 year old’s on hand… 
