Author Topic: Adding sugar to fermenter to lower FG?  (Read 281 times)

Offline Joe_Beer

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Adding sugar to fermenter to lower FG?
« on: October 07, 2020, 05:11:21 PM »
I have some wort fermenting from last weekend which had an OG of 15.5 brix. It's an IPA kit I've made before using US-05. I'm using Kveik this time around and no idea what the final gravity will come out to. I'd like to shoot for 7.5 brix for a 6.68% (at 1.04 wort correction). If the FG stops above 7.5 would adding some sucrose to the fermenter get the yeast working again to lower the FG?

Offline dmtaylor

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Re: Adding sugar to fermenter to lower FG?
« Reply #1 on: October 07, 2020, 05:20:57 PM »
Adding sugar will jack up the alcohol to your desired level, but really will NOT reduce the FG at all.  It's not a bad idea, but it just doesn't work quite the way you might want it to.

Now.... if you were still in the mode of designing the recipe, you could swap out some of the malt for sugar, and THAT would reduce the FG compared to a 100% malt beer.  But, that's not what you are dealing with here, if it's already in the fermenter.  Just an idea to keep in mind for next time.

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Offline denny

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Re: Adding sugar to fermenter to lower FG?
« Reply #2 on: October 07, 2020, 05:53:27 PM »
Adding sugar will jack up the alcohol to your desired level, but really will NOT reduce the FG at all.  It's not a bad idea, but it just doesn't work quite the way you might want it to.

Now.... if you were still in the mode of designing the recipe, you could swap out some of the malt for sugar, and THAT would reduce the FG compared to a 100% malt beer.  But, that's not what you are dealing with here, if it's already in the fermenter.  Just an idea to keep in mind for next time.

Cheers!

THIS^^^^
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Offline Joe_Beer

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Re: Adding sugar to fermenter to lower FG?
« Reply #3 on: October 07, 2020, 06:07:52 PM »
Thanks. I've been reading up on how late sugar additions can throw off the hop profile along with the overall body and character of the beer. I'll see where the gravity is in a couple days. Maybe the Kveik will finish out lower than the US-05 did and won't need it. Mainly wondering if adding the sugar would put the yeast back to work again.

Offline denny

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Re: Adding sugar to fermenter to lower FG?
« Reply #4 on: October 07, 2020, 06:21:52 PM »
Thanks. I've been reading up on how late sugar additions can throw off the hop profile along with the overall body and character of the beer. I'll see where the gravity is in a couple days. Maybe the Kveik will finish out lower than the US-05 did and won't need it. Mainly wondering if adding the sugar would put the yeast back to work again.

It might, but adding sugar will increase your OG so your FG may not be any lower.
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Offline Joe_Beer

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Re: Adding sugar to fermenter to lower FG?
« Reply #5 on: October 08, 2020, 08:26:53 PM »
It might, but adding sugar will increase your OG so your FG may not be any lower.

I had to think about this for a bit. I think I see what you mean. Adding fermentables raises the OG which increases the overall drop from OG -> FG which is really what dictates the ABV. Is that right?  If so, what affects if a beer finishes at 1.015 or 1.035? Just yeast attenuation?

back at the fermenter... The wort has been dropping about .3 brix every day for the past few days but today it didn't so figure it was done. It was 8.8 brix this morning and the same 10 hours later. I boiled a little water in the microwave, took it out and added a 1/2 cup of sugar. Let it cool to room temp and then added some wort from the spigot. I didn't want to pull the lid, so mixed it around with a big syringe and dispensed it though the airlock grommet. I swirled the whole fermenter around to get things mixed up. It's sitting at 9.8 brix. Would the expectation be that it will get down to 8.8 brix again at some point?

Offline ynotbrusum

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Re: Adding sugar to fermenter to lower FG?
« Reply #6 on: October 08, 2020, 08:49:02 PM »
It might, but adding sugar will increase your OG so your FG may not be any lower.

I had to think about this for a bit. I think I see what you mean. Adding fermentables raises the OG which increases the overall drop from OG -> FG which is really what dictates the ABV. Is that right?  If so, what affects if a beer finishes at 1.015 or 1.035? Just yeast attenuation?

back at the fermenter... The wort has been dropping about .3 brix every day for the past few days but today it didn't so figure it was done. It was 8.8 brix this morning and the same 10 hours later. I boiled a little water in the microwave, took it out and added a 1/2 cup of sugar. Let it cool to room temp and then added some wort from the spigot. I didn't want to pull the lid, so mixed it around with a big syringe and dispensed it though the airlock grommet. I swirled the whole fermenter around to get things mixed up. It's sitting at 9.8 brix. Would the expectation be that it will get down to 8.8 brix again at some point?


Final gravity is mainly based on fermentability of the wort, attenuation of the yeast (could be strain dependent and viability dependent) and fermentation temperature to some degree.  I suppose there could be other factors in rare instances, like we mentioned above as to pH being way out of whack being a consideration to some lesser degree.  Some British strains do not ferment specific complex sugars, for example, so the final gravity for the strain is higher than a voracious more attenuative yeast under the same circumstances.
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Offline denny

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Re: Adding sugar to fermenter to lower FG?
« Reply #7 on: October 08, 2020, 09:25:30 PM »
It might, but adding sugar will increase your OG so your FG may not be any lower.

I had to think about this for a bit. I think I see what you mean. Adding fermentables raises the OG which increases the overall drop from OG -> FG which is really what dictates the ABV. Is that right?  If so, what affects if a beer finishes at 1.015 or 1.035? Just yeast attenuation?

back at the fermenter... The wort has been dropping about .3 brix every day for the past few days but today it didn't so figure it was done. It was 8.8 brix this morning and the same 10 hours later. I boiled a little water in the microwave, took it out and added a 1/2 cup of sugar. Let it cool to room temp and then added some wort from the spigot. I didn't want to pull the lid, so mixed it around with a big syringe and dispensed it though the airlock grommet. I swirled the whole fermenter around to get things mixed up. It's sitting at 9.8 brix. Would the expectation be that it will get down to 8.8 brix again at some point?

Yeast attenuation ratings areban way of comparing one yeast to another and don't necessarily aff3ct the attenuation you'll get.  The fermentability of the wort really determines it.  Adding sugar make a more fermentable wort, but as mentioned above, you need to sub sugar for some of your malt in the original recope.  Adding suga4 now would simply make it like you started with a higher OG.
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Offline Saccharomyces

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Re: Adding sugar to fermenter to lower FG?
« Reply #8 on: October 09, 2020, 08:37:35 PM »
Some British strains do not ferment specific complex sugars, for example, so the final gravity for the strain is higher than a voracious more attenuative yeast under the same circumstances.

Many of those strains are the result of the use of invert sugar in traditional British brewing.  Invert sugar combined with low original gravities are a recipe for selective pressure that results in low-attentuating yeast strains.

Offline Joe_Beer

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Re: Adding sugar to fermenter to lower FG?
« Reply #9 on: November 02, 2020, 12:08:23 PM »
Just to follow up on this experiment, I'm pretty satisfied with the results. The extra sucrose didn't seem to affect the profile adversly enough to make it unpleasant. A couple other people tried it as well and they didn't think it was overtly sweet or undrinkable. Getting the recipe and boil right is certainly a much cleaner way but If my wort ever needs an extra point I'll certainly try this again. Thanks all!