just a thought on attenuation

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lowlife

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I see people say add sugar to drop final gravity. In cases where people have a beer that is too sweet does this really do anything? Isnt it just creating more alcohol (which is lighter than water) so the gravity drops? Arent the same unfermentable sugars in there (and therefore just as sweet) even though the gravity is lower (due to more alcohol)?
If I am way off I will blame it on too many wee-heavies tonight
 
yeah , i agree, except I think you will remain at the same OG. I see it this way, it you added the sugar at flameout, you'd get a higer OG. But if you had unfermentables in there the added sugar wont affect FG. The addition of sugar will make the beer drier and appear lighter ( i think) but i dont see where it can magically make yeast want to eat away at unfermentables.
 
The added CORN SUGAR would indeed ferment out resulting in a drier brew.

Any sweetness due to the added sugar would have to be hop compensated to add more balance.

The sugar would make it a higher OG, but will also result in a lower FG. ;)

Sometimes attenuation is off. For instance, I fermented a cider with Weihenstephan Weizen yeast. It's projected attenuation is 75%. My OG was 1.100. At the projected attenuation of 75% my FG should have been 1.025. Right? No way...my FG right now is 1.000.
 
See the recent thread in another forum. My rudimentary reading is that the extra sugar restarts fermentation and somehow gets the yeast to finish off some fermentables it didn't get to before... I'm willing to be wrong. I'm curious to know what the correct answer is. I understand commercial breweries use this technique - if so there must be something to it.
 
See the recent thread in another forum. My rudimentary reading is that the extra sugar restarts fermentation and somehow gets the yeast to finish off some fermentables it didn't get to before... I'm willing to be wrong. I'm curious to know what the correct answer is. I understand commercial breweries use this technique - if so there must be something to it.


Oh I think you're probably right about restarting fermentation and finishing off fermentables, but I dont think just adding more alcohol to a batch and keeping the unfermentables constant would lower a gravity reading. There's also more than one way to restart fermentation: rousing the yeast and trub, increasing the temp, adding beano, adding more yeast, etc. My commnet up top, was for a scenario where fermentation was really completely done.
 
but I dont think just adding more alcohol to a batch and keeping the unfermentables constant would lower a gravity reading

It will. Alcohol is lighter than water (and malt), so the higher the ABV, the lower the gravity (with constant unfermentables). You can test this easily by adding an ounce of vodka to a pint of beer, checking the gravity before and after.
 
My question is- adding more alcohol (from sugar) doesnt actually make a sweet beer seem less sweet or does it (after fermentation is done)

I was drinking some weeheavy last night wishing it was a tad drier.
 
Yeah but somethings just not making sense to me, I mean your also changing the volume of the beer. I agree you'll get some change in gravity, but you'd also get a change in gravity by adding plain water. My only point is the true unfermentables are there to stay , unless you use beano or something right?


I think the addition of alcohol from sugar does make the beer drier and give a sweet/malty beer a diff taste, percieved or not.
 
Adding sugar may not change the amount of residual sugars present (although as a couple of posters suggest, maybe it will by restarting fermentation). But independent of that, it will reduce the malto-dextrine "feel" of the beer -- it'll feel less thick in body, because it is less thick, even though the residual sugars are the same. That thickness/body is part of what we experience as sweet in beers.
 
I think very often when people reference adding sugar to 'dry out' a beer, they mean when brewing it again, replace some of the grain bill/extract with sugar; so that you end up with the same OG but the FG will be lower.
 
Sometimes attenuation is off. For instance, I fermented a cider with Weihenstephan Weizen yeast. It's projected attenuation is 75%. My OG was 1.100. At the projected attenuation of 75% my FG should have been 1.025. Right? No way...my FG right now is 1.000.

I seem to remember from one of the Basic Brewing Radio podcasts with a guy from Wyeast, where he said that the advertised attenuation is determined experimentally with a base wort that they use company-wide. So if you're using a wort with a very different composition from theirs, you will get a different observed attenuation. A cider is bound to be much more fermentable than the wort they used to come up with the number. So the attenuation % they tell you isn't reliably usable as an absolute, but it is useful to compare with other yeasts from the same company (a 75% attenuation yeast from Wyeast has 25% higher attenuation than a 60% attenuation yeast from Wyeast).
 
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