Author Topic: Attenuation of RIS  (Read 2101 times)

Offline edward

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Attenuation of RIS
« on: May 04, 2010, 09:30:33 AM »

I mashed 24 lbs of grain, sparge 12 gallons of water, and boiled down to 5.5 gallons.  My OG was 1.113 - I pitched two packets of dry yeast (Notty).   After 3 weeks my gravity was at 1.042, I pitched 2 lbs of sugar and 2 packets of champagne yeast.  After another 3 weeks the gravity was still at 1.042 (i.e. the champagne yeast ate only the sugar).  I was rousing the yeast every day.

The overall attenuation was ~65%. Its been in the secondary for 3 months and the gravity reading has not changed.  I think the ABV is ~12.5%.  I was hoping that 3 months in the secondary would drop the gravity by another 4 to 6 points.

At this point I am debating whether or not to pitch more yeast or to just bottle it. Time is not an issue for me.  I am just worried about the beer being too sweet.  Although, the last sample I took did not taste overly sweet. 

If I pitch more yeast would I need to re-aerate and transfer back to a primary?  I was thinking about adding maybe three more packets of dry yeast to see if I could drop the gravity into the 1.035 range.

Opinions are welcomed!

Offline redbeerman

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Re: Attenuation of RIS
« Reply #1 on: May 04, 2010, 09:32:22 AM »
What was your mash temperature?  You may be finished.
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Offline bonjour

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Re: Attenuation of RIS
« Reply #2 on: May 04, 2010, 10:02:03 AM »
in general big beers should be mashed for attenuation or fermentability, that means lower mash temps and longer mash times, there are other factors at play but these are the most important.

If you have a good history on your system with your target yeast you should be able to approximately predict your FG.

Just chart your results and it should be quite obvious.

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Offline edward

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Re: Attenuation of RIS
« Reply #3 on: May 04, 2010, 10:11:12 AM »
I mashed at 146 for 90 minutes.  I did three sparges to get the boil volume.  I did a temperature ramp with the sparges though.  146 to 154 to 160.  Boiling the whole time after the first sparge.

My last RIS on this same system came in at about 75%.  The OG was much lower though, maybe around 1.106.

Offline a10t2

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Re: Attenuation of RIS
« Reply #4 on: May 04, 2010, 10:22:25 AM »
If you added sugar and the SG didn't change, that actually means that only about 3/4 of the sugar was consumed by the yeast. I would bet it was the original yeast at work too - when the dry champagne yeast hit that 9% ABV solution a lot of it was probably killed off.

I think your best option now is to pitch an actively fermenting starter at high krausen. Hopefully that will get you some more attenuation. You are at 68% apparent attenuation now though, so I don't know how much more of a drop I would expect.
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Offline babalu87

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Re: Attenuation of RIS
« Reply #5 on: May 04, 2010, 10:45:06 AM »
Why dont more people do Fast Ferment tests?

Jeff

On draught:
IIPA, Stout, Hefeweizen, Hallertau Pale Ale, Bitter

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Hefeweizen,Berliner Weisse, Mead

Offline bluesman

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Re: Attenuation of RIS
« Reply #6 on: May 04, 2010, 11:47:33 AM »
Have you calibrated your hydrometer lately?
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Offline tom

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Re: Attenuation of RIS
« Reply #7 on: May 04, 2010, 01:05:44 PM »
How does it taste?

Same recipe as last time?
Brew on

Offline edward

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Re: Attenuation of RIS
« Reply #8 on: May 05, 2010, 02:52:37 AM »
Why dont more people do Fast Ferment tests?



I had heard of it but never really looked into it.  I finally read it on Kaiser"s site and I may do it my next brew.  I usually have the problem of being slightly over attenuated.  Then again I have never made a beer this big before.

Offline edward

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Re: Attenuation of RIS
« Reply #9 on: May 05, 2010, 02:54:19 AM »
Have you calibrated your hydrometer lately?

I usually calibrate the low end with water every few months.  It is always reading perfect.  I have never had a reason to doubt it.

Offline edward

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Re: Attenuation of RIS
« Reply #10 on: May 05, 2010, 02:55:26 AM »
How does it taste?

Same recipe as last time?

It tastes pretty good.  It is not the same recipe as last time.  This one is a clone (my take) of Bell's Expedition Stout.

Offline babalu87

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Re: Attenuation of RIS
« Reply #11 on: May 05, 2010, 04:47:12 AM »
Why dont more people do Fast Ferment tests?



I had heard of it but never really looked into it.  I finally read it on Kaiser"s site and I may do it my next brew.  I usually have the problem of being slightly over attenuated.  Then again I have never made a beer this big before.

Thing with the FFT is you would know three days after brewing what your FG will be within a point or two.
I'd have to check but I've done this test on roughly 300 gallons of beer and it is dead nuts within a point or two every time.

It really helped me on a Wee Heavy this past Fall.
I set my electric mash tun wrong and the mash hit 160+, I knew I was doomed but waited for the FFT
I ended up watering down the second runnings 90/0 to an 80/-  and after some aging its a pretty damn good beer.
The Wee Heavy is now a Wee Sour coming along nicely in a corny.
Jeff

On draught:
IIPA, Stout, Hefeweizen, Hallertau Pale Ale, Bitter

Primary:
Hefeweizen,Berliner Weisse, Mead

Offline edward

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Re: Attenuation of RIS
« Reply #12 on: May 06, 2010, 01:40:24 AM »
I dont know if it will do any good but I pulled maybe a pint of the beer off and added a whole bunch of yeast to it.

A better late than never FFT.

I guess we'll see what happens.

Offline tom

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Re: Attenuation of RIS
« Reply #13 on: May 06, 2010, 11:15:06 AM »
How does it taste?

Same recipe as last time?

It tastes pretty good.  It is not the same recipe as last time.  This one is a clone (my take) of Bell's Expedition Stout.
Can you post the recipe? Does it have more unfermentables?
Brew on

Offline edward

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Re: Attenuation of RIS
« Reply #14 on: May 07, 2010, 03:09:51 AM »
How does it taste?

Same recipe as last time?

It tastes pretty good.  It is not the same recipe as last time.  This one is a clone (my take) of Bell's Expedition Stout.
Can you post the recipe? Does it have more unfermentables?

5.5 gallon recipe

23 lb pale 2-row
1 lb flaked barley
1.5 lb roasted barley
1 lb black patent
1 lb 80 L crystal
.5 lb chocolate malt
3.3 lb amber malt extract
2.5 oz Centennial 10% 45 min
1.5 oz Centennial 10% 30 min
.5 oz Centennial 10% 0 min

mash at 150-152

For 5 gallons
At 60% brew house efficiency
OG 1.150
FG 1.038
IBU 105
ABV 14.4

At 50%
OG 1.130
FG 1.033
IBU 115
ABV 12.5


I used less two row and extract.  This was published in Zymurgy in 2003.