I had a rash of infections a couple of years ago. Acetobacter. Now I can pretty much spot it by the faintest whiff or taste and certainly by sight. You’d be surprised how many expensive craft and European brews I’ve bought that were infected.
Now batches go into the kegs no longer than 10 days once FG is stable. If the brew tastes ok at that point the slurry is either used immediately or not at all. I avoid using yeast a third time.
And yes I like to keep dried yeast around since it is so handy, cheap and reliable.
I don’t like reusing yeast which to do effectively and safely one needs a microscope and the right technique(s). Bacteria may be present in the first batch in minute amounts and not enough to affect the brew but in successive batches they will make themselves known. Not that it can’t be done or tried but is definitely advanced homebrewing.
It seems to me that the batches I make that use a saved yeast cake turn out better than the ones I make a starter for. I don’t think it’s for only advanced homebrewers as long as you keep things clean and sanitized.
+1 - I love reusing yeast and I often thing the second and third generation is far better. Also, if you have a lot of acetobacter infections I would recommend skipping the secondary and, if using buckets, making sure you get the beer out of the bucket and into the package as soon as possible once fermentation is over. Acetobacter can’t grow under a co2 blanket. The only times I have ever seen acetobacter is in buckets or carboys where I let the airlock go dry.
Oh no I never said not to do it! In fact my last batch was a fresh repitch. My theory as to why it’s better is that there’s alot more yeast and they are more active. Just be forewarned that infections can crop up this way no matter how sanitary one is. It would be wise to check yeast health and for bacteria and for that one should use a microscope.
That being said I’d be reluctant to use yeast from a high-gravity beer. They’ve been through the wringer at that point.
I’ve got a jar of Frankenyeast that I occasionally use and/or re-propagate that is maybe a decade old. Started out as something, Windsor or Nottingham maybe, dumped into a pint jar w/tin foil on top in the fridge. I use it occasionally in my 7% lawnmower by just dumping in the whole pint and then pouring another pint full after racking. If it has been awhile - a couple of months maybe - I start feeling sorry for them and will make a gallon starter out of some saved up and canned 3rd runnings just to give them a little treat. I have no idea how many generations have evolved or even what they have evolved into.
After primary fermentation, I save the yeast in a flask which is then simply covered with foil and stored in the back of my beer fridge. I don’t wash the yeast…I’ve tried it and it’s a pain and makes no difference in the results, so I don’t bother.
When reusing yeast, the only time I do a starter is if the yeast has been in storage for more than 4 weeks. Other than that, 1/3 to 1/2 of the stored slurry is all that’s needed for the next batch.
I totally agree with other observers that the flavor improves considerably after the yeast has gone through a few re-uses.
My house yeast is like tubercle’s “Frankenyeast”…I’ve kept it going for 20 years and counting and it’s used for 90% of the brews I make.
This may seem like a stupid question, but it has been befuddling me since I’ve began reading about repitching yeast, how is repitching yeast and different than the yeast companies harvesting them?
I get that some of the yeast is going to be ‘worn out’, I understand there could be mutations (biggest difference, since scientific knowledge is a huge gap betweeen two processes) causing some variability, and the growth environments are different. Is the environment the key difference? Yeast harvesting I am assuming they are pump with oxygen throughout to keep them reproducing versus in a beer where we are trying to avoid adding additional oxygen. I could be way off base, far from my area of expertise.
I believe the difference is that the yeast are grown under aerobic conditions similar to when we use a stir plate or continuous O2. This gives them stronger cell walls and better sterol reserves. Regardless, as you alluded to, when WL or WY harvest their yeast they are at peak viability. When we harvest yeast from the bottom of a fermenter much of it is dead and the cells have depleted much of their sterol reserves.
As an aside I have been growing yeast under continuous aeration and collecting the slurry and it is pretty amazing how much healthier they seem. Fermentations start quicker and don’t seem to take nearly as long as with slurry or 1st gen starters.
How long would you say is the shelf life of a mason jar of slurry that has been sitting in the fridge? I’ve got a jar of WY2124 and another of one of their special strains that is probably 6-8 months old now. I’m thinking that it’s probably too old to use. It doesn’t look any different than when it fist settled, however, and I have not done a sniff test yet either.