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Do yeast die after bottling?

My second batch of beer have been stored in bottles over a month now without producing any co2. I want to add some priming sugar to start the fermentation again, but I'm unsure if it will help.

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At what temperature are you holding the bottles? –  baka May 19 '12 at 23:44
    
They are stored in my bathroom. 18-25c with a average about 20c. –  Olsenius May 20 '12 at 0:01
    
You may have forgotten the priming sugar in the first place if there was no CO2... –  brewchez May 20 '12 at 13:17
    
We actually forgot to add the priming sugar in the first place. I had bottled 2-3 bottles when we remembered. I added 5g per liter and redid the first bottles. –  Olsenius May 20 '12 at 13:29
    
In answer to your question of do yeast die after bottling. There should be enough especially if someone can resurrect a yeast strain from a weevil trapped in amber: dsc.discovery.com/news/2008/09/23/ancient-yeast-beer.html :-) –  Chris Plaisier May 22 '12 at 15:30

3 Answers 3

up vote 6 down vote accepted

Yeast will become dormant and eventually die after a few weeks to months, but only after any food sources, like priming sugar, have been consumed.

The lack of carbonation after a month could be caused by a number of things

  • insufficient yeast - normally there is yeast in suspension after primary, but a highly flocculative strain may settle out completely. For bottling, 10,000 cells per ml is considered a typical cell density.

  • if the priming sugar was added to the entire batch, it may not have been mixed with the beer fully, leaving some bottles without sugar and others an excess.

  • the bottle caps are not on airtight

  • your temperature of 19-25c should be warm enough, but typically cold temperatures can hinder fermentation.

Adding more priming sugar can be done on a bottle or two as a test, which you can open after 3 days. You should hear a hiss, but the beer itself won't be carbonated unless it's left for another week. But if you get the hiss then the yeast are working it's most likely a problem with distributing the priming sugar evenly. No hiss, and you may need to pitch some more yeast. A tiny pinch of yeast is enough for the entire batch, but putting a tiny pinch of yeast in each bottle will work also.

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Thanks. I will try to prime a couple of bottles again. –  Olsenius May 20 '12 at 9:47
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I disagree with the cell count as a likely reason. I brew alot with very flocculant english strains. Even after a month in a carboy at cool temps there is still plenty of yeast in suspension to carbonate. Its nearly impossible to drop so much yeast that beer doesn't carb. –  brewchez May 20 '12 at 13:17
    
Depends on the circumstances. If the bottles have been sitting for a month without any priming sugar at warm temperatures, cell counts will have dropped 10 fold or more, and there won't be enough yeast to carb the beer. –  mdma May 20 '12 at 23:02
    
I opened a few bottles last night. The first one was flat, and i added some boiled sugar to it. The next 3 beers had much co2, and the foam came out of the bottles. It seems like the priming sugar weren't mixed good enough into the beer before bottling, as you suggested might be the problem. –  Olsenius May 21 '12 at 19:55
    
Olsenius, this is precisely why using a bottling bucket is popular; you make your syrup (boil and cool to a yeast-safe temp), pour it into your sterilized bottling bucket, then transfer the beer from fermenter to bottling bucket. I also like to sterilize a large all-metal spoon and give it a healthy stir after transfer. (Remember to keep splashing/aeration to a minimum.) At that point, rack the beer to bottles, cap, and you're done. –  CaffeCaldo May 22 '12 at 14:53

Yeast are pretty hardy and it takes time before they completely die off. Even when the nutrients are nearly all consumed the yeast simply go dormant. I have cultured yeast out of beer bottles that were at least a year old. Granted the total viability isn't high but they aren't all dead. Alcohol levels, oxygen levels and storage temp plays a big role.

In your case, adding more priming sugar should work as I am sure there is plenty of yeast around. Be sure the beer is at 70F/21C before starting. You want the beer at room temp as the yeast see the sugar. For ease you may want to try something like Coopers carb tabs. Little pills of sugar for carbing one bottle at a time.

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The question has essentially been answered, but I'd like to suggest that you also check out the following rather informative write-up regarding the yeast lifecycle which I've found informative:

http://www.beer-brewing.com/beer-brewing/brewers_yeast/yeast_life_cycle.htm

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