Diacetyl Test
- Thread starter Mesa512
- Start date
Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:
I think you've misread the term 'Diacetyl rest'.
Basically Diacetyl is a product of yeast fermentation. It gives the beer a buttery/rancid taste and so should be removed with a simple 'diacetyl rest'.
To perform a diacetyl rest simply leave the beer in the fermenter for a few days once primary fermentation has finished. This gives the yeast a chance to 'clean up' the by-products of their fermentation including the diacetyl.
There is a test you can do to check whether the diacetyl rest has done its job:
Pull a sample from your fermenter and split it into two covered containers. Refrigerate one and heat the other to 140°F for an hour, then taste them both. If they taste the same, you're ready to rack your beer out of the fermenter. If you can taste butter in the heated sample, your yeast is still at work, and you should give it another day or two.
Source:Beer Me! Down With Diacetyl!
- oneleg
Basically Diacetyl is a product of yeast fermentation. It gives the beer a buttery/rancid taste and so should be removed with a simple 'diacetyl rest'.
To perform a diacetyl rest simply leave the beer in the fermenter for a few days once primary fermentation has finished. This gives the yeast a chance to 'clean up' the by-products of their fermentation including the diacetyl.
There is a test you can do to check whether the diacetyl rest has done its job:
Pull a sample from your fermenter and split it into two covered containers. Refrigerate one and heat the other to 140°F for an hour, then taste them both. If they taste the same, you're ready to rack your beer out of the fermenter. If you can taste butter in the heated sample, your yeast is still at work, and you should give it another day or two.
Source:Beer Me! Down With Diacetyl!
- oneleg
So, isn't this proof that there really IS a "Diacetyl Test"?
makisupa
Well-Known Member
There's a Diacetyl Force Test you can do.
• Heat one sample from your carboy for 10-20 minutes @ 160-deg via a double boiler (make sure the sample has aluminum foil over the top)
• Keep a second sample at room temp
After heating the one sample for 10-20 minutes, smell both. Does one smell like butter? If neither smell like buttery diacetyl then there's no worry of it being present. If the heated sample smells and the room temp doesn't then leave the beer on your yeast longer (diacetyl rest). If they are both positive for butter it either, like the case above, needs more time on the yeast, or you might have an infection (however, RDWHAHB).
Check out "Yeast" by Chris White and Jamil. It's a great read.
• Heat one sample from your carboy for 10-20 minutes @ 160-deg via a double boiler (make sure the sample has aluminum foil over the top)
• Keep a second sample at room temp
After heating the one sample for 10-20 minutes, smell both. Does one smell like butter? If neither smell like buttery diacetyl then there's no worry of it being present. If the heated sample smells and the room temp doesn't then leave the beer on your yeast longer (diacetyl rest). If they are both positive for butter it either, like the case above, needs more time on the yeast, or you might have an infection (however, RDWHAHB).
Check out "Yeast" by Chris White and Jamil. It's a great read.
wheidem1
Member
Would Diacetyl present in the beer produce a slippery, soapy feel on the tongue? Do you know is it possible to perform this test on beer that has already been carbonated? (granted its too late to give it more time in a fermenter with the yeast, but would one observe the same results, i.e. the buttery smell?)
Here is a test you can do http://www.professorbeer.com/articles/diacetyl.html
it's tword the bottom the page.
it's tword the bottom the page.
Yes i've done the above test on carbonated beer and it worked fine.
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