Why would my FG's be off?

[Kayos]

I am hitting my OG's, but the FG seems to be off by about 5 points or so. This just doesn't make sense to me. I am using a starter with Wyeast or WL. Not sure how I can make an improvement on this. Thoughts?

 

[Brewsmith]

Are you using extract or doing all grain?

Airation may be a factor. If the yeast are running out of gas and not multiplying enough to get the job done, then oxygen may be a factor. If you are using extract, it may be the fermentability of the extract.

 

[Kayos]

AG. I shake the crap out of the carboy after brewing.

 

[Brewsmith]

Can you give an example of a recipe and gravity readings?

 

[Kayos]

Type: All Grain
Date: 2/1/2008
Batch Size: 5.50 gal
Brewer: Jake
Boil Size: 7.33 gal Asst Brewer:
Boil Time: 90 min Equipment: Brew Pot (7.5 gal) and Igloo Cooler (10 Gal)
Taste Rating(out of 50): 35.0 Brewhouse Efficiency: 72.00
Taste Notes:

Ingredients

Amount Item Type % or IBU
8.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 66.67 %
1.25 lb Barley, Flaked (1.7 SRM) Grain 10.42 %
1.25 lb Cara-Pils/Dextrine (2.0 SRM) Grain 10.42 %
0.75 lb Chocolate Malt (350.0 SRM) Grain 6.25 %
0.75 lb Roasted Barley (300.0 SRM) Grain 6.25 %
0.80 oz Magnum [12.69 %] (90 min) Hops 35.8 IBU
1 Pkgs Irish Ale (Wyeast Labs #1084) Yeast-Ale



Beer Profile

Est Original Gravity: 1.054 SG
Measured Original Gravity: 1.054 SG
Est Final Gravity: 1.014 SG Measured Final Gravity: 1.020 SG
Estimated Alcohol by Vol: 5.21 % Actual Alcohol by Vol: 4.43 %
Bitterness: 35.8 IBU Calories: 245 cal/pint
Est Color: 33.3 SRM Color: Color


Mash Profile

 

[DeathBrewer]

what temperature do you mash at?

 

[Kayos]

Mash Name: Single Infusion, Full Body Total Grain Weight: 12.00 lb
Sparge Water: 3.92 gal Grain Temperature: 72.0 F
Sparge Temperature: 168.0 F TunTemperature: 72.0 F
Adjust Temp for Equipment: TRUE Mash PH: 5.4 PH

Single Infusion, Full Body Step Time Name Description Step Temp
45 min Mash In Add 14.40 qt of water at 171.8 F 155.0 F
10 min Mash Out Add 6.00 qt of water at 206.1 F 168.0 F



Mash Notes: Simple single infusion mash for use with most modern well modified grains (about 95% of the time).
Carbonation and Storage

Carbonation Type: Corn Sugar Volumes of CO2: 2.4
Pressure/Weight: 4.2 oz Carbonation Used: -
Keg/Bottling Temperature: 60.0 F Age for: 21.0 days
Storage Temperature: 58.0 F

 

[DeathBrewer]

any temperature swings during fermentation?

 

[Kai]

How confident are you in your thermometer? If your thermometer is reading a little low, then you could accidentally be mashing, say, at 158, which would reduce your fermentability a bit. Try mashing lower, see how the beers turn out.

Also, try a fancy-pants aeration system if you feel like spending a few bucks.

 

[EbenezerScrews]

Temp swing

I got the weird recipe from northern brewer:

Specialty
.5 Victory Malt
.5 Briess Caramel 60

Fermentables
1 lb Pilsen DME
6lb Amber LME(20)

Hop .5oz Summit(60)

Fat Tire Yeast(80 degree F 10min)

My ferment at 77F 12 hours, 75F 24h, 70F 48h, 70 now 72h

is this a flucuation in temp?

 

[EbenezerScrews]

Ambient is 68F consistent, sorry

 

[Søren T]

You are mashing at full body temp. Try light body next time. That will give you a more fermentable wort.

I suppose you shake to areate? There is not much oxygen in the head space. Try plunging the wort into the carboy when racking from the kettle.

 

[DeathBrewer]

or get an aquarium pump and a hepa filter...shaking won't give you very much oxygen.

 

[the_bird]

That's a LOT of Carapils, especially combined with a high-ish mash temp.

I've never really felt the need to use a lot of Carapils. Basically, it adds unfermentable dextrines to add body and head retention. You can have more long-chain dextrines by keeping your mash temp high (like you have, at 155°). I'd wager that the combination of the 10% carapils and the high mash temp is resulting in a wort with a lot of unfermentable sugars. Drop the Carapils (or maybe keep a half-pound or so), drop the mash temp to 152° (dependant on recipe, of course), and you'll pick up some attenuation.

 

[Soulive]

That's a LOT of Carapils, especially combined with a high-ish mash temp.

I've never really felt the need to use a lot of Carapils. Basically, it adds unfermentable dextrines to add body and head retention. You can have more long-chain dextrines by keeping your mash temp high (like you have, at 155°). I'd wager that the combination of the 10% carapils and the high mash temp is resulting in a wort with a lot of unfermentable sugars. Drop the Carapils (or maybe keep a half-pound or so), drop the mash temp to 152° (dependant on recipe, of course), and you'll pick up some attenuation.

+1...I have never used that much Carapils. Recently I haven't been using any, but I used to only use about 1/2lb in the past...

 

[Beerthoven]

I don't use Carapils at all. I think it was developed for use by large breweries who cannot easily change their mash temps to achieve higher body. Seems like an unnecessary cheat for homebrewers.

 

[Evan!]

I don't use Carapils at all. I think it was developed for use by large breweries who cannot easily change their mash temps to achieve higher body. Seems like an unnecessary cheat for homebrewers.

It's not really cheating, it's about control. I've never found the difference between 149 and 155 to be all that reliable, but the inclusion or lack thereof of carapils is. To each his own, though...maybe I'm the Roger Clemens of homebrewing, but I like to use carapils.

 

[the_bird]

...maybe I'm the Roger Clemens of homebrewing, but I like to use carapils.

Oh, MAN! If this was in one of the off-topic forums, I've got a punchline all lined up to go! DAMMIT!

 

[the_bird]

I don't really think of Carapils as cheating, per se - no more than using melanoidin malt in lieu of doing a decoction is cheating. Just, if you're going to mash for low fermentability (i.e. high temp), you don't want to be ALSO using a malt used to decrease fermentability. I think a lot of people just throw Carapils in their recipes by default, without really thinking about it; it doesn't belong in an IPA (IMHO), for example, yet I see it there all the time.

 

[Brewsmith]

I agree with bird on the carapils in the recipe, and it's use in general. Between the carapils, the flaked barley and the high mash temp, there's going to be tons of unfermentables in that beer. Before you go adding carapils in recipes, play with the mash temperature.

 

[jdoiv]

yeah, it looks like you have about 23% of your grist in crystal malts and carapils. 70+% of the sugars from those are not going to get fermented. This will leave you with a high finishing gravity. You could try counteracting by mashing lower, say 144 or so, or as others have mentioned cutting back on the carapils/crystal malts. An oxygen system would help some as well.

 

[Kayos]

Ok, food for thought on the Carapils. This was the same recipe as Flanagan's Stout, but I was trying for a higher ABV, so I upped everything keeping the ingredient %'s the same.

 

[Brewsmith]

When going higher in gravity, the body is going to increase anyways by having more unfermentables in the wort, even from the base malt. The extra carapils isn't necessary. Also, a higher mash temp on a big beer can leave extra long chain sugars that also leave the beer thick and sweet. When going higher gravity, you generally want as much fermentability as possible so that it is not cloying.

 

[Kayos]

I was only at 1.054 SG. Would you consider that a "big" beer? I think I get it on the Carapils and other unfermentables. I was just trying to keep the % the same thinking it would work out, but what you say makes sense. AG is really intriguing and this is a great reason why!