Author Topic: High FG predicted  (Read 1816 times)

Offline brian_muz

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High FG predicted
« on: January 15, 2021, 09:16:05 PM »
Hi,

I've been setting up a brew in BS based on this recipe from BYO.com:

(5 gallons/19 L, all-grain)
OG = 1.102  FG = 1.026
IBU = 30  SRM = 60  ABV = 11.4%

Ingredients
12 lbs. (5.4 kg) American 2-row pale malt
2.5 lbs. (1.1 kg) malted oats
2.5 lbs. (1.1 kg) Weyermann Caramunich? III malt
12 oz. (0.34 kg) chocolate malt
12 oz. (0.34 kg) Briess Midnight Wheat malt
8 oz. (0.23 kg) roasted barley
1 lb. (0.45 kg) lactose
8 AAU Magnum hops (60 min.) (0.5 oz./14 g at 16% alpha acids)
Wyeast 1968 (London ESB), White Labs WLP002 (English Ale), or LalBrew London English-Style Ale yeast

The author has the FG at 1.026.

I've built the recipe in BS but the predicted FG is 1.048. I wouldn't expect them to be exactly the same but that's a pretty huge difference.

I've attached the bsmx file of my recipe. I've had to scale it but you can see the %s are the same. I've also had to substitute some grains but again, I haven't made a major change here that would account for 22 points.

To be clear I'm not saying something is wrong with BS. I'm just trying to understand why they are so different and why the FG is so high.

Thanks.

Offline Oginme

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Re: High FG predicted
« Reply #1 on: January 16, 2021, 06:01:16 AM »
What you are running into is a limit set by the max alcohol tolerance of the yeast strain you have selected.  The max alcohol content is listed as 8% in your profile, so the program caps the alcohol content at 8% and assumes the remainder is not fermented.  This appears to be out of date, as the Wyeast web site lists max tolerance as 9% for WY1968. 

Since you are brewing a very high alcohol content beer, my suggestion if you want to stick with this strain would be to overpitch by a fair amount of healthy, viable yeast.  The best way to do this, in my opinion, is to create a vitality starter of 1 liter of wort about 8 hours before you want to pitch it into the beer.  It should be at high krausen by the time you are ready to pitch and you can go ahead an pitch the whole thing into the fermenter.

Alternatively, you can pitch an additional package of yeast.

This is by no means a guarantee of full attenuation of your wort, but it will give you a fighting chance and retain much of the yeast character of the WY1968.
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Offline brian_muz

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Re: High FG predicted
« Reply #2 on: January 16, 2021, 02:06:47 PM »
Thank you so much @Oginme. I've been trying to work out what the issue was and couldn't work it out. The tolerance of the yeast strain never crossed my mind as I've never reached it before. I might try subbing out the yeast. Or, I'll see how far I can get with 1968 and then pitch a second yeast with a higher tolerance to finish off. Thanks Again!

 

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