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how does bottle carbonating work?

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Enpitsu

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so i've always wondered....how does carbonating in a bottle with priming sugar work? here's my confusion:

during fermentation, isn't all the yeast and its by products settled to the bottom? so, when i move it over to the bottling bucket with the priming sugar, no yeast comes over to produce some CO2 from the sugar?

i guess the follow up is - if i let ferment for an extended period of time, say 1.5 months, do i risk not having enough yeast leftover to properly carbonate?
 

stevo155

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When you transfer, there is plenty of yeast in suspension to carbonate your beer. Even if you cold crash it, not all the yeast drops. This is evident when you open a bottle carbonated beer and there is yeast sediment in the bottom of the bottle.
 
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There is still enough live, active yeast in suspension to eat the priming sugar.

To further ensure that, a lot of us will stick the wand down into the compacted yeast cake for a second or two just to get some into the bottling bucket (this is likely not needed, but a lot of us still do it).
 

ChshreCat

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The yeast cake at the bottom of your fermenter is the flocculated yeast. Meaning the yeast that has clumped together and then became heavy enough to sink. Much of the yeast is still in the beer, suspended and too small to see without a microscope. There are people here who bulk age beer for months in a carboy before bottling and have no issues with carbonating. Don't sweat it.
 

natehilde

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In terms of home brew, there will always be enough yeast left in suspension to provide for natural carbonation.

Yeast are extremely small micro organisms. 2-5 micron in sized depending on the reproduction phase. When clarifying beer (most home brew), gravity is the motive force. As the size of a suspended particle diminishes, the drag coefficient on that particle gets closer to the force causing the settling action. This results in an exponential increase in the time required for complete removal of all suspended solids.

There is a plethora of excellent information out there on home brewing. Don't hesitate to ask questions here, but the more research you do on your own, the more well-rounded your brewing education will become.
 

SumnerH

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so i've always wondered....how does carbonating in a bottle with priming sugar work? here's my confusion:

during fermentation, isn't all the yeast and its by products settled to the bottom? so, when i move it over to the bottling bucket with the priming sugar, no yeast comes over to produce some CO2 from the sugar?

i guess the follow up is - if i let ferment for an extended period of time, say 1.5 months, do i risk not having enough yeast leftover to properly carbonate?
To add to what others have said, 1.5 months isn't really an extended fermentation. It's not until you get into longer fermentations (many months) that you normally start worrying about having enough viable yeast to bottle condition, though with big beers it can be a slow process.
 

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