Vangers 2.0
Usually not worth it; you'll need to gently distill (in proper glass, this is important) the beer like it is done for ABV measurement and measure density of leftovers. Or do quantitative chromatography. You've got to know hands-on chemistry real well for this. Let me know if you need the procedure.
Only once I've got yeast staggered by lemon juice addition, and that happened in secondary fermentation. If there is enough sugar (and, if I recall correctlt, there was added sugar in these ferments), they'll keep going. Acidity that slows them down for real is much higher, like what acetobacteria do. Yeast still thrives in bread starters and combucha, and those are sour!
There you go, now we know the answer for "what was thinking that person who chopped the very last tree on Easter island?"
Was it pulpy? Particles tend to stabilize liquid interfaces.
Yeast does this if they are in really sweet spot for sugar, nitrogen, microelements, temperature, and pH. Almost always happens in braggot (once shot into ceiling with lock, was quite a mess), also if you add yeast fertilizer. I think I saw this reported reproducively for slightly over 23C lager yeast. And, well, insufficient headspace might be a problem. Don't worry, at least yet.
So are you adding sugar this time or not?
Are those hops good? Would you share a bit of rhizome for me to clone?
I can't stop thinking that Finnish hops grown in chill weather might be a hidden treasure, once we figure out how to tune the recipes.
But how bad is the washing?
I completely agree that keeping yeast supply lines as local as possible is a good idea, both in terms of distance, and in terms of time. That's the concept here - if we can't get fresh local yeast, then we should make them.
Getting yeast from breweries is good idea, but first, those should ideally come from in-brewery lab, not from propagation (unless it's some kind of local native yeast, I suppose) - fresh lab-propagated yeast always behave much better according to my experience and to literature, also lines tend to mutate or degenerate otherwise without proper single-cell cleaning step occasionally.
Second, as far as I understand, most breweries keep very small selection of yeast. One of the reasons we've got into cultivation of pure varietal yeast is a realization of yeast's impact on final product profile. This was quite a story.
At that point we were much younger and we've doubted that yeast could make lots of impact on fermentation profile, much less dominate it, as literature occasionally claims. Once we've decided to compare several different strains of yeast in mead; we've taken the most straightforward starting material - honey from Texas where we lived back then, that's got all possible flowers blooming almost year round mixed together so that no single flavor could be distinguished - turned it into a must, then divided it into 8 batches and pitched them with different wine yeasts. Expecting subtle difference, we were surprised to find that some turned out like mead, but others were slightly honey-flavored Pinot Noir, Cabernet Sovignon, Riesling, etc. That was the day we've started thinking about building yeast library. Now we keep tasting (I mean, perform organoleptic analysis, it's science!) plain pilsner 1040OG wort with no additions but yeast - and every new strain brings something new, while old strains become as familiar as friends. It's a whole world.
They are certainly good for 20L, that's the amount we use for typical homebrews ourselves.
So ok, these are just quasiparticles. Yes, we could have quasiparticles that behave like actual particles. Yes, it's just an abstraction. Yes, we can go batshit crazy in abstraction space and come up with anything.
This reminds me how some folks in ScientificAmerican modeled black hole with a vortex in water and found supersonic wave, which brought them to conclusions about possibility of passing through event horizon in actual black hole. bah.
In other words, when do I get some money to build a quantum quasiparticle computer and finally hack elliptic cryptography?
Though, as Rice alumni, can't deny still always awesome publicity of that university.