Sugar carbonation and ABV

Hi again folks,

To all you really experienced brewers this may sound crazy.
It seems to me that when I carbonate with table sugar before bottling, my ales definitely get stronger the longer I age them.
Is the sugar still picking up residual yeast and converting slowly over time.
Please note the beer is really good, at least after one or two everybody tells me so, then they phone a taxi !!!

Mike

There will be an increase in alcohol but it depends how much sugar you are putting in. The residual yeast is what creates your carbonation by eating the sugar you are putting in, this creates CO2 and alcohol.

Hi,
I already knew that, but how does one know how much residual yeast exist prior to bottling, if there were none there would be no carbonation

I guess that would depend on how much you suck up with your siphon?

Hi again,
Lets assume that there is no residue in the bottom of my bottling bucket so no danger of being sucked up by the siphon. This is always true as I siphon to the bottling bucket when the sugar is added.
This being the case, how does one accurately predict the alcohol strength of the beer once bottled?

Thanks again

hi audlyn,
as i understand it (and i've only been brewing for 6 months so might have it completely arse about face) the yeast will only convert the fermentable sugar in your wort. when there is no more fermentable sugar to convert, fermentation stops. at this point the fermented wort will no longer be making alcohol but it will still have yeast in suspension within the liquid. these are the yeast particles that convert the sugar you add at bottling to create the co2 and a small additional alcohol content. i believe that there are complicated calculations you can make to get the exact alcohol increase that the sugar adds (i don't understand them at all but you might however it is my understanding that the basic rule is that you add .4% abv for the alcohol increase from the sugar added.
if i have understood your question however, the fact that you are adding a finite amount of fermentable sugars to the already fermented wort means that the yeast in suspension will only be able to convert the sugar you have added. once these have been converted the beer will have achieved it's maximum alcohol content and after this it will not change as the yeast will no longer have any fermentables to convert ... thus making it impossible for your beer to carry on increasing in alcohol volume.
again, i want to point out i'm a noob as well so could be completely wrong, but that's my understanding of the process!
hope this helps,
jon

Five ounces of sugar will add .26% ABV when added to five gallons of beer.  Unless you use a microscope there is no definitive way to know how much yeast is in a bottle of beer.  Luckily it takes very little yeast to convert the priming sugar to CO2 and a little alcohol.

Your beers may seem stronger as they age because they have matured and are at the best stage for enjoying.

jonnym_ch said:

however it is my understanding that the basic rule is that you add .4% abv for the alcohol increase from the sugar added.
... thus making it impossible for your beer to carry on increasing in alcohol volume.

Click to expand...

^^ This.

Yeast make CO2 and alcohol in a 50/50 format. So, if significant strength were achieved in the bottle, the beer would probably decant itself all over your floor. Likely, there is something else at play in the perception of additional strength. For instance, fusel alcohol from increased primary fermentation temperatures can give you slight headaches during and after drinking.

Thanks for that Jonny , Flars,and Brewfun
As you will have noticed I am no expert at this but I do know I brew good beer, which carbonates well in the bottle using the required amount of table sugar.I've never had a problem with the carbonation and to date no "beer bombs" touch wood
I am still trying to get my head round this "efficiency" malarkey.
I'm tempted to extend my mash and my boil both to 90 Min's and see what that does .
Nothing ventured nothing gained as they say.
I'm not really into all the rocket science of this and am quite happy to brew popular drinkable  beer.

Mike

I'm going to fully agree with jonn and flars. Any ferment able sugars should be consumed during fermentation. When you bottle carbonate, you're adding a very small amount of additional ferment able sugars and the yeast that remains in suspension will gobble it up and create a small amount of alcohol and CO2. Once that process is over, the remaining yeast will fall out as there is no longer any ferment able sugar to consume.  I think jonn described it best.

Ok guys,
It must be something else that I am doing, or not doing??
All my Ales and especially IPA, which is popular are fermented at a constant controlled temp of 20C over 4 weeks. I recently brewed a Mexican lager which is now into its 2nd week of fermentation at the controlled temp of 12 C and it will stay there for a few weeks yet.
My guess is that my fermentation method is ok but there may be issues with my Mash and Sparge,
What,s your guess??
Mike

If you haven't already done so, read "How to Brew" by John Plamer. An older version is available (free) on-line at: howtobrew.com

The print version is a little more up-to-date, but the free version is excellent explains a lot of the details of mashing, sparging, yeast, and fermentation.

Ill jump in late and offer my worthless opinion lol.  Could it be that the tastes and mouthfeel etc is getting better as it bottle ages?  I know my amber ales have a period around 2-3 weeks where they are drinkable but 'thin' and 'weak' but after another 2 weeks they are awesome and around 2 months in bottles they seem to stabilize and taste how I expect.  I opened one last night thats about 3 months old and it seemed very carbonated and had a HUGE head on it, but Im blaming that on my pouring and being tired.  Ill test another couple tonight.