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Old 07-12-2017, 10:10 AM   #1
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Default Cold crashing, clearing etc

Apologies if this has been asked before.

I’m a bit confused on cold crashing and techniques for clearing etc.

I’ve done two kit batches of ale so far and a few turbo ciders, I don’t have barrels so everything is bottle conditioned. At present I’m putting a couple in PET bottles and leaving in the warm (20ish degrees) till the bottles are pretty hard then in the shed for a couple of weeks. First batch had a bit more but now I’m seeing around 1mm or so of sediment on the bottom of the bottles (batch priming in a secondary has helped) and the beer/cider itself is almost as clear as shop-bought once poured into glass.

Which ramblings bring me to the question. I’ve heard about cold crashing, adding “irish moss” or gelatin at some point. Is this something I could/should bother with if I’m happy with the final drink? Is it going to reduce the sediment in bottles (I understand that’s a product of carbing in the bottles)?

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Old 07-12-2017, 11:01 AM   #2
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The sediments is the yeast settling out from the beer once it's done consuming the carbonating sugars. Generally all bottle conditioned beers have some amount of yeast in the bottom.

Irish moss is added at the end of the boil, whereas gelatin is added after fermentation. Gelatin causes most of the yeast and other debris (like hops) to drop out of suspension, leading to a clearer beer.

Cold crashing is the process of dropping the temperature of the beer once fermentation is complete. There are different temps you can drop to, I've seen some people drop to 4C, and others to -1C. This encourages the yeast and other stuff to drop to the bottom of the fermenter, which in turn will lead to clearer beer. The risks with cold crashing are that air will get sucked back into the fermentor (unless you are cold crashing in a keg) due to the contraction of the air and the beer reabsorbing some CO2. Whether this is of a major concern, is up to you.

Essentially you are coldcrashing your beer when you put the bottle in the fridge. By doing it before you bottle, you are just removing a bit more yeast from the beer before you bottle it.

Overall this is just a visual thing, and does little to affect the over flavour of the beer. So if you are happy with your beer, carry on as you are.

Nothing will cause all the yeast to drop out, there will still be enough to bottle carbonate.

I've only coldcrashed one beer that had 187g of dry hops in it. It did help a bit to get all the debris down to the trub.
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Old 07-12-2017, 12:01 PM   #3
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As @svenito wrote, once fermentation is over some homebrewers drop the temperature of the beer. This puts to sleep any yeast cells that are not already dormant, encourages the settling of sediment and brightens the beer. Although Americans, in their brash, overconfident way, have used the term "cold crashing", it is referred to as "cold conditioning" (
Once this bright beer is bottled and primed the yeast gets to work again so there will always be sediment in your bottle. I leave bottles at fermentation temperature for 2 weeks then store them in an unheated shed to chill them down to encourage settlement of sediment.
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