Hitting Final Gravity

Physics, chemistry and biology of brewing. The causes and the effects.

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Hitting Final Gravity

Postby Suthrncomfrt1884 » Thu Jan 29, 2009 7:44 pm

So I just bottled an imperial nut brown last sunday. I was going through some calculations trying to figure out ABV and IBU's when I realized I never hit my calculated final gravity.

Target for my original recipe was around 1.010-1.015. I ended up bottling at 1.023, so it was still pretty high.

I took hydrometer readings 3 days in a row and it stayed at 1.023 the whole time. The kraussen had fully fallen in. I'm assuming the yeast just had enough.

What problems, if any, could this cause? I did notice it had a very high alcohol presence at bottling time. I'm hoping that might settle out in time.



My recipe is as follows if it helps.

1lb Munich
.5lbs Crystal Malt 20L
.5lbs Carmel Malt 40L
.5lbs Chocolate Malt
2.25lbs Dry Extra Light Extract
6.4lbs Liquid Light Extract (late addition)
1oz Saaz (5.8%) 60min
.75oz Mt. Hood (4.8%) 60min
.75oz Arg. Cascade (3.5%) 60min
11oz Maple Syrup (end of boil)
1 tsp. Irish Moss
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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Where's the Yeast?

Postby brewmeisterintng » Thu Jan 29, 2009 7:51 pm

Some yeasts do not take kindly to higher alcohol levels. While others finish higher. Did you pitch enough? That is usually associated with a yeast starter.
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FG

Postby slothrob » Fri Jan 30, 2009 8:27 am

The yeast will make a difference one way or the other, but I think 1,020 is a more realistic FG for this recipe.

Firstly, the beer is pretty big with an OG of 1.070 (I assume), so at 70-75% attenuation, which was typical for me when I used extract, we're talking about 1.017-1.021. Maybe higher, depending on the brand.

Also, I know I harp on this, but the more Crystal Malt you use, the more unfermentables you'll add. I've read that each pound decreases your attenuation by 2%, so the 1.5# you used would bring you in line with your 1.023 FG.

What yeast did you use?
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Postby Suthrncomfrt1884 » Fri Jan 30, 2009 2:16 pm

I used Wyeast Scottish Ale 1728. The yeast is a little out of place with this recipe but I used it for it's ability to ferment higher gravity beers.

My OG was 1.081. It sounds like it did it's work though. So originally I was thinking this was going to finish around 9 or 10% abv....now it's looking like around 7.8-8%. Is that right?
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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1728

Postby slothrob » Fri Jan 30, 2009 2:46 pm

1728 is a low attenuator at 69-7%. 1.023 FG from 1.080 OG is 71% attenuation, so it looks like the yeast hit right in the middle of it's range.

If you want to make a drier beer from extract, without reducing the amount of Crystal Malt, you need to replace some of the DME with about an equal weight of table sugar or corn sugar. That will replace some of the partially fermentable extract with fully fermentable sugar, giving you a lower FG. Using sugar to lighten the body has been a common technique among British and Belgian breweries.
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Postby Suthrncomfrt1884 » Fri Jan 30, 2009 5:43 pm

Thanks for the info everyone.

This brew was actually just a way for me to get rid of a lot of extra ingredients. I just finished building an all grain system, so I won't need to worry about using extracts very often from now on.
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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Postby jawbox » Fri Jan 30, 2009 5:58 pm

pictures of the new system would be cool soco.
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MacBook 2.16 Ghz Intel Core 2 Duo, 1GB Ram, Mac OSX 10.6.2
IMac 2.93 GHz Intel Core 2 Duo, 4GB Ram, Mac OSX 10.6.2
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I like macs ;)
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Postby Suthrncomfrt1884 » Sat Jan 31, 2009 4:52 pm

No problem. I'm brewing again next weekend. I'll take some pics of it in action.
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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