Yeast Viability after bottling

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MN_Jay

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I was wondering how long yeast would remain viable after a beer is carbonated. Say if you opened a fully carbonated beer and let it go flat, then you added some sugar in there and recapped, would it recarbonate again?

Taking it a step further, could you grab a commercial beer and do the same? If this would work then could you take the yeast slurry off the bottom the bottle and keep stepping it up? It would be a great idea if you are trying to do a clone right?

Or am I way out to lunch here? I'm also not sure of the legality of this either.
 
Taking it a step further, could you grab a commercial beer and do the same? If this would work then could you take the yeast slurry off the bottom the bottle and keep stepping it up? It would be a great idea if you are trying to do a clone right?

People do this all the time. I am yet to do it, but plan on harvesting yeast from a Bell's for my next IPA. Of course, it only works if the commercial beer is not filtered or pasteurized.
 
Harvesting yeast from bottles is a totally viable, and pretty common technique, whether it's your own beer or from a professional brewery. To my understanding, things that might affect the viability of the yeast are age and the alcohol percentage of the beer you're culturing from (higher alcohol puts more stress on the yeast).
 
Yes thats totally a common practice, in fact all of my beers come from yeast I've gotten from the bottom of bottles, I've never used yeast from Wyeast or White labs. Although I plate my yeast out and select single colonies then grow them up rather than direct from the dreg.

Viability is quite variable, with some bottles being full of viable cells but others have a nice dreg but grow absolutely nothing on a plate. Time and method of storage seem to explain why some have low viability.

If you do decide to go directly from the yeast at the bottom of the bottle be sure to start from a very small amount of wart, like 50ml or even less. I've started them from 10ml. Then step up after you start seeing sighs of fermentation. I do this in small glass vials rather than in the old bottle, but many people just use the bottle for the starter.
 
^^This^^ The guys in Australia do this with Cooper's sparkling ale,as the commercial yeast is different. It took some up to 5 days to see any action though.
 
Interesting. So whats the procedure for doing this for a commercial beer? Do you open it and let it warm up and go flat or do you pitch some sugar or dme as soon as you open the bottle? I'm actually surprised this works - I'd love to try this for a commercial clone of some sort.
 
Interesting. So whats the procedure for doing this for a commercial beer? Do you open it and let it warm up and go flat or do you pitch some sugar or dme as soon as you open the bottle? I'm actually surprised this works - I'd love to try this for a commercial clone of some sort.

Open, decant to glass, add a little sterile 1.040 wort to the dregs, place cap back over bottle in a clean place (don't touch the inside, obviously), drink beer, then step up over several days until you have a starter.
 
Interesting. So whats the procedure for doing this for a commercial beer? Do you open it and let it warm up and go flat or do you pitch some sugar or dme as soon as you open the bottle? I'm actually surprised this works - I'd love to try this for a commercial clone of some sort.

It's not too hard as long as you are sanitary. I have harvested all by Belgian yeasts from bottle conditioned ales. Wipe the mouth and cap of the beer with sanitizer, pour yourself a glass of tasty brew, saving the dregs in the bottom, much as you would with pouring a homebrew. Then I transfer the dregs to a sanitized container to start stepping up.

I start with a small amount (100 ml) of weak wort 1.010 or so, when I see activity i transfer to to a 1 liter erl flask, and add about 200ml of 1.020 wort. After a couple of days I will see activity, I add about 500ml of 1.030-1.040 wort, put on stir plate and let run for a few days.

I cap the head of flask with foil, as I do not want any undue pressure on yeasties.

After a few days on stir plate, I am ready to cold crash, decant, and make the actual starter.

Does it take a while? Sure, but I have managed to get a dozen or so different yeasts this way, that may not otherwise be commercially available.

You just need to make sure the commercial examples you are using, have harvestable yeasts.
 
I pour the beer into a glass then shake the glass to stir up the dreg in the last 10ml of beer that is left. Then I drip a single drop of this on to an agar plate made with DME at a 1.040 concentration. Then I streak out this drop across the plate and wait 3-5 days. Pick a colony with a transfer wand and place it in 10ml of new 1.040 wort in a tube. Step up as fermentation starts. I also make a slant from the plate and save it in my fridge, the slant is good for a year or more.

This may be a bit more complicated than what your looking for at first but you might consider it since its a lot easier than it seems and if you get interested there are lots of good posts about each of these steps. All of this can be done with simple equipment, you don't even really need a pressure cooker. I just use a rice cooker.
 
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