Author Topic: Forced Fermentation Test  (Read 7201 times)

Offline edward

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Forced Fermentation Test
« on: January 13, 2011, 05:48:52 AM »

I ran a FFT on a Belgian Dark Strong for 4 days at room temp (68F +/- 2 F)) and tested a gravity of 1.010 from an OG of 1.100.  I used about 300ml of wort to 75ml of Wyeast 1214 slurry.  I only aerated during the first hour of the test.  This is my first time doing an FFT.

My questions are this:  since this is way overpitching, can I really expect the same level of attenuation (90%) out of the batch in the fermenter (the beer is fermenting at room temp under similar levels of oxygenation)?    Is there an optimal yeast to wort ratio for the FFT?

Besides an overabundance of alcohol the FFT sample didn't taste too bad.  What kind of taste difference can I expect from the FFT vs. the final product?  I was hoping for a moderately high dark fruity ester profile but it was quite low, peppery phenolics were off the chart.  There were also very little malty flavors present.

Offline hokerer

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Re: Forced Fermentation Test
« Reply #1 on: January 13, 2011, 08:40:15 AM »
If you mean Fast Ferment Test, then Kai has a good article on his wiki about it...

http://braukaiser.com/wiki/index.php/Fast_Ferment_Test
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Re: Forced Fermentation Test
« Reply #2 on: January 13, 2011, 08:51:54 AM »
hokerer, Thanks for posting the link.


My questions are this:  since this is way overpitching, can I really expect the same level of attenuation (90%) out of the batch in the fermenter (the beer is fermenting at room temp under similar levels of oxygenation)?    Is there an optimal yeast to wort ratio for the FFT?

The attenuation difference between FFT and final beer is something that you’ll have to base on experience. I know that some residual sugars work well in a Doppelbock while they don’t work well in a Pilsner. Let the beer finish fermenting. Then take a sample if it tastes too sweet and the FG is still above the FFT FG you know that there are still sugars that the yeast can ferment.

There is no optimal yeast to wort ratio. Just keep in mind that too much yeast, more than 5% for example, might be able to skew the results by bringing in too much of a different OG/FG beer. That beer was your starter beer. But you don’t have to worry about that if you re-suspend the yeast sediment with the wort to be tested before you pitch the yeast and keep a little bit for the FFT.

Quote
Besides an overabundance of alcohol the FFT sample didn't taste too bad.  What kind of taste difference can I expect from the FFT vs. the final product?  I was hoping for a moderately high dark fruity ester profile but it was quite low, peppery phenolics were off the chart.  There were also very little malty flavors present.
Don’t use the taste as an indication of the beer taste. I do taste my FFTs, but only out of curiosity.

Kai

Offline edward

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Re: Forced Fermentation Test
« Reply #3 on: January 13, 2011, 09:21:53 AM »
If you mean Fast Ferment Test, then Kai has a good article on his wiki about it...


I think I may have heard it called a Forced Ferment Test somewhere.



There is no optimal yeast to wort ratio. Just keep in mind that too much yeast, more than 5% for example, might be able to skew the results by bringing in too much of a different OG/FG beer. That beer was your starter beer. But you don’t have to worry about that if you re-suspend the yeast sediment with the wort to be tested before you pitch the yeast and keep a little bit for the FFT.



I used the dregs of a quart jar where I had stored a slurry and the amount of yeast ended up being a liitle bit more than I had anticipated.  In the future I will try to get a little more wort to make it easier to obtain the FFT sample.  Grabbing a bunch of the cold break and letting it settle out in a large pitcher works pretty well for getting wort samples and doesn't take away from the final beer.

.

Offline gimmeales

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Re: Forced Fermentation Test
« Reply #4 on: January 13, 2011, 12:43:52 PM »
Quote
I think I may have heard it called a Forced Ferment Test somewhere.

I think they can be two different things actually, at least from what I've deduced from threads on the ProBrewer forums.  The way I read it was that the 'Forced' test was to help determine possible infection\flaw sources, whereas the 'Fast' test is used primarily for determine potentially finishing gravity.
« Last Edit: January 13, 2011, 02:09:56 PM by gimmeales »

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Re: Forced Fermentation Test
« Reply #5 on: January 13, 2011, 12:54:03 PM »

I think they can be two different things actually, at least from what I've deduced from threads on the ProBrewer forums.  The way I read it was that the 'Forced' test was to help determine possible infection\flaw sources, whereas the 'Fast' test is used primarily for determine potentially finishing gravity.

That’s how I have been seeing this as well. The “forced ferment test” is also known as “wort stability test” which is a less confusing name. Fast ferment test also works well with the German name for this test: Schnellgaerprobe (literal: fast-ferment-sample).

kai

Offline edward

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Re: Forced Fermentation Test
« Reply #6 on: January 14, 2011, 05:15:14 AM »

That’s how I have been seeing this as well. The “forced ferment test” is also known as “wort stability test” which is a less confusing name. Fast ferment test also works well with the German name for this test: Schnellgaerprobe (literal: fast-ferment-sample).


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Offline Thirsty_Monk

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Re: Forced Fermentation Test
« Reply #7 on: January 16, 2011, 02:18:48 PM »
I was always curious about FFT but have never done it.
I should start doing this one of these days.
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Offline edward

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Re: Forced Fermentation Test
« Reply #8 on: January 24, 2011, 05:36:57 AM »
After two weeks I measured a gravity of 1.013 and racked into a carboy for aging.  Sample tasted pretty good.  Even with 12%+ alcohol it did not have the "hotness" or "alcohol" type flavors.

The FFT was pretty close and the gravity may yet drop a point or two.

Offline gimmeales

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Re: Forced Fermentation Test
« Reply #9 on: January 24, 2011, 09:37:16 AM »
I myself, finally remembered to take a sample for FFT when racking into the fermenter last night.  Brewed a big Old Ale (1.091), so interested to see where it ends up and how close the rest of batch gets to that number.  Being a big beer, it will be nice know where it should end up, so after 3-4 weeks I'm not stuck wondering 'will it go lower?'

Offline seajellie

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Re: Forced Fermentation Test
« Reply #10 on: January 26, 2011, 07:22:56 AM »
Apologies for the thread drift, but does anyone have experience using wine yeasts to do a FFT?

I had been under the impression that Belgian beer yeasts and wine yeasts were genetically, possibly, not all that distant from each other. And most wine yeasts have very high levels of alcohol tolerance. So I thought I could use a dry wine yeast to do a FFT on a dunkel. I always have lots of extra wine yeast around, and it was my first go at using 100% munich malts and so wanted to monitor the ferment.

The FFT stalled at 1.020; the dunkel fermentation (with WL833) is now at 1.016 and appears to still be going. I think I did the procedure correctly, so this appears to be a simple case of the wine yeast not liking those munich malts. The OG was 56 so the alcohol level is well within the tolerance for this Lalvin yeast (k111 I think).

Kai recommends using bread yeast.

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Re: Forced Fermentation Test
« Reply #11 on: January 26, 2011, 08:37:44 AM »

The FFT stalled at 1.020; the dunkel fermentation (with WL833) is now at 1.016 and appears to still be going.

bread yeast is S. cervesiae (sp?) which is the ale yeast species. But I don't exactly know what species wine yeast is. Possibly S. bayanus, if I remember correctly. Lager yeas is actually a hybrid between these two yeasts which means that you inclination to use wine yeast is correct. But I'm surprised about the difference between the FFT and the actual fermentation which you are seeing.

Kai

Offline tschmidlin

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Re: Forced Fermentation Test
« Reply #12 on: January 26, 2011, 11:12:44 AM »
Yes, wine yeasts are generally S. bayanus, lager yeasts are currently classified as S. pastorianus (used to be S. uvarum or S. carlsbergensis).  Yeast taxonomy gets ugly, don't get me started :)
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Re: Forced Fermentation Test
« Reply #13 on: January 26, 2011, 02:34:49 PM »
Apologies for the thread drift, but does anyone have experience using wine yeasts to do a FFT?

I'm sure it would work, but the results wouldn't be applicable to the fermenter with the beer yeast. AFAIK no wine yeast strains can ferment maltotriose, so the FFT gravity would likely be higher than the main batch.
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Re: Forced Fermentation Test
« Reply #14 on: January 26, 2011, 03:15:46 PM »
AFAIK no wine yeast strains can ferment maltotriose, so the FFT gravity would likely be higher than the main batch.

That would explain the difference he is seeing.

Kai