Diacetyl Test

[HomeDrewBrew]

I did a diacetyl test from a batch of light lager that smelled and tasted very butterscotchy a few days prior to testing. So with the testing i took a hydro sample full split into two mason jars and heated one to 160 for ten mins then foiled and cooled in fridge where the other sample was at. Then when both at same temp i sampled.
#1(non heated) It smelled a little butterscotchy but not as much as it was before.
#2(heated) this one tasted like a light lager uncarbed sample should and completely different then sample #1.

So my question is since sample #1 still has a bit of buttery smell to it and taste should i leave at room temp to rest more?.

Also..Why does the heated sample taste different and in my mind better?.

Thanks

 

[HomeDrewBrew]

Also i should add its been in keg at 2c since i racked cause i didnt taste it after gravity sample but DIDNT do the test then it came out after week n keg.

 

[brewcat]

A few more days at room temp won't hurt.

I think you need to keep the heated sample covered while heating.

 

[Weezy]

Diacetyl is volatile. The heating drove it off.

The heating test should be done with the sample covered. The goal is to get the diacetyl evacuated but contained, so you can smell it in that trapped air space.

 

[VladOfTrub]

I am not familiar with the method that was used during the test for diacetyl but, the following is the way that it has been performed for beaucoup years. Take 2 samples of the beer. Heat one sample to about 140 or so for an hour. Use some foil to cover the sample to be heated. The other sample leave at room temp. After you heat the sample allow it to cool to the same temp as the other sample. Remove the foil and smell the cooled down sample. If it still smells like butter, diacetyl is present. If it doesn't have the butter smell, taste it and taste the other sample, as well. If the samples taste the same, you're good to go. If the sample smells of butter or tastes different than the other sample, you'll need to perform a diacetyl rest on the beer and krausen the beer later on.

Kudos on the diacetyl test. However, it's better to perform the test during first fermentation. Diacetyl becomes noticeable generally during second fermentation or sometimes later on when the beer is in the bottle and keg. Performing the test during first fermentation, forewarns.

Now, that you know that you can produce diacetyl, it is better to clean up the brewing procedure than to go through the trouble of beating up Lager yeast by increasing temperature. Beer is krausened when a diacetyl rest is performed, it makes up for the yeast that was wiped out during the rest. The rest temporarily removes diacetyl, the precursor is still there and diacetyl will reform later, it is only a matter of time. Unless, the brew master is attempting to create a perfect level/balance of diacetyl, the occurrence becomes extra work and anxiety.

Diacetyl forms when something goes haywire during first fermentation. Usually, when wort lacks oxygen, nutrients, is sugar imbalanced, poor quality yeast and or not pitching enough yeast, any one increases the chance of diacetyl forming. They are easy to fix.

When everything is fixed there won't be a need to perform a diacetyl rest, try not to change anything.

 

[brewcat]

Diacetyl forms when something goes haywire during first fermentation. Usually, when wort lacks oxygen, nutrients, is sugar imbalanced, poor quality yeast and or not pitching enough yeast, any one increases the chance of diacetyl forming. They are easy to fix.

Or some yeasts just produce more diacetyl...

 

[VladOfTrub]

Or some yeasts just produce more diacetyl...

Let us know which ones.

 

[Yooper]

Or some yeasts just produce more diacetyl...

Let us know which ones.

Usually, it's English strains where sometimes the diacetyl is considered part of the character of the beer and not a flaw. Ringwood is the first one that comes to mind, but if you do a google search, you can certainly find the others.

There are a couple of lager strains that produce more copious amounts of diacetyl as well. Others produce minimal amounts. It's really strain dependent, but you can look at some of the common ones and find that data.

 

[HomeDrewBrew]

Thanks for all the input guys and gals!
I used 34/70 and fermented at 50 for 9days and raised to 65 but i think i shouldnt of waited to ramp so late .
I tasted it after the diacetyl test with the samples and it tasted way better and that was a day after the test.
So its been in freezer for 2days carbing and im gna try a sample and see if it still tastes like butterscotch and if so ill have to Krausen.

 

[VladOfTrub]

Thank you for the great information about the different types of yeast. I enjoy an Ale with a trace of diacetyl but not too much. I wish that I knew how to control diacetyl.

 

[Yooper]

Thank you for the great information about the different types of yeast. I enjoy an Ale with a trace of diacetyl but not too much. I wish that I knew how to control diacetyl.

You are welcome.

I wish you had the ability as well.