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-   -   ABV calculation after backsweetening (http://www.homebrewtalk.com/f32/abv-calculation-after-backsweetening-348185/)

 Zippox 08-17-2012 12:59 PM

ABV calculation after backsweetening

I remember reading a thread that mentioned that the ABV is much harder to calculate when you backsweeten.

I was wondering if we start with a OG of 'x.xxx' and end with 'y.yyy' after it ferments dry and I backsweeten to 'z.zzz', to calculate ABV is it not fair to just use x.xxx and z.zzz with an online calculator?

I'll be making a cider with a start of around 1.062, ferment dry, then backsweeten to around 1.014 (or thats a tentative plan). Any insight is appreciated.

 CollegeCider 08-17-2012 01:29 PM

It depends if when you backsweeten, all the sugar gets fermented out or not. If you assumed it did, the calc is (x.xxx-y.yyy)*131.25= ABV after initial fermentation.
Lets say the carbonation takes it to 1.000, then you would do (z.zzz - 1.000)*131.25=carb ABV, then do carb ABV + ferm. ABV=total ABV.

 CollegeCider 08-17-2012 01:30 PM

So basically enter to the online calc x.xxx and y.yyy, write down ABV given. Then enter in the calc z.zzz and 1.000 and add that to the origional ABV

 LeBreton 08-17-2012 02:57 PM

An SG of 1.062 fermented to dryness gives an ABV of ~8.1%.

Do not add the extra 0.014 to your ABV since this will not get fermented as these sugars are what are keeping your cider sweet.

If bottle conditioning your cider add around ~0.5% to the total ABV and subtract about 0.003-0.004 SG from the sweetness.

 Zippox 08-17-2012 03:03 PM

In response to CollegeCider - I understand what you are saying if I were to let it go dry after backsweetening, but that would be defeating my intent of adding sweetness back.

I am hoping to get somewhere between 5 and 6% ABV so I thought I would start around 1.062, ferment till 1.000, add juice concentrate to bring it back up to 1.014 let it carb up and then pasteurize though I am open to suggestions.

My final goal is to have it be around that 1.014 mark in the end so I guess I now have a few questions:
• How many points does carbonating bring it down?
• Would I want to add the standard 3/4 cup of table sugar so that the sweetness level stays the same after carbonating, or just continue adding a certain amount of concentrate?
• And to re-ask the ABV question, If I were to follow steps similar to what I mentioned, how would ABV be calculated most precisely? -It seems hard to figure out because we are changing the volume slightly and everything.

I understand that most of this stuff doesn't matter as long as it tastes good, but I find it fun to know the stats of my drinks :)

 CollegeCider 08-17-2012 03:15 PM

You wont be able to calculate abv precisely, unless after you have it carbed up and pasturized, you open a bottle, let it go flat and then take a SG reading. (carbonation would mess with hydrometer) and then do (OG-FG)*131.25 + (OGafter sweetening-FG after flat)*131.25. Otherwise do as LeBreton said and do (OG-SG)*131.25 +.5%, as I think I remember reading somewhere that it usually takes ~.004 to carb up.

 Zippox 08-17-2012 03:25 PM

I didn't realize that backsweetening doesn't really lower the ABV much.

My plan was to start with Mott's Apple Juice (Probably normal and not Natural one because I want a clear and light cider), and add whatever necessary to have an ABV of 5ish and a moderate level of sweetness. If anyone wants to chime in with suggestions here that would be appreciated, I am trying to figure out if I need to add any sugars at the starting point and around how much juice to backsweeten with.

I assume a lot of this would depend on the SG of Mott's normal apple juice so if anyone knows that number that would be helpful.

 CollegeCider 08-17-2012 03:29 PM

If you want an ABV of 5%, the SG difference between OG and FG would need to be .038. Mott's apple juice last I checked was 1.05-1.055, so you would probably not need to add any sugar to start or backsweeten, as you would be stopping fermentation at 1.012-1.017.

 Zippox 08-17-2012 04:40 PM

So you think it would be best to catch it when the SG is around 1.017 (not possible to cold crash right now for me), bottle it, wait for it to carb and then pasteurize? Perhaps I will need to learn how to use gelatin or something then if I wanted to clear it up before bottling.

 CollegeCider 08-17-2012 10:13 PM

Yeah, that should be fine, just check the carbonation periodically as it will carb faster then if you primed it to carb up. To me, it doesnt really matter if you bottle clear/cloudy as it clears in the bottle anyways. You just end up with more sediment in the bottom. Others may say differently, but thats my opinion. You will definitely want to bottle pasteurize though. Also, check the OG and adjust accordingly. Different bottles can have different SGs.

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