Understanding abv and low fermentability adjuncts.

[Stevedkiwi]

Hi all,

I have posted this query on a few software makers sites etc but do not seem to warrant a reply (I'm beggining to think I have the plague or something, maybe my questions are just plain too dumb !!!)

1. I note that most software does not add anything to the ABV to account for the priming sugar e.g abv is calcualted on OG less FG which surely doesnt allow for the approx .4 to .5% added due to fermentation of the priming sugar. Why ???

2. I also note that the various software programmes seem to treat low fermenatbility ingredients such as lactose and maltodextrine differently.

By my reckoning an ingredient like maltodextrine should add to OG and FG almost equaly since it has very low fermenatbility. Some programes (e.g. Beersmith) treat it as a "misc" ingredient so do not include it in gravity calcs at all. Others include it as an adjunct or sugar and increase the OG accordingly butt then increase the FG by a much lower amount as though it had been largely (Say 75%) fermented.

In a further twist some prgrammes treat M/dextrine as a misc but lactose (Which has an even lower fermentabilty, but basicaly the same effect), as a grain or fermentable adjunct. go Figure !!

What am I missing here !!!

Cheers

Steve D

novice brewer (but really keen to learn the underlying nuts and bolts)

 

[Nateo]

1) 4oz of dextrose in 5 gallons of beer would raise the gravity maybe 1.002 at the most, which would be about 0.1% ABV. We're talking about an amount that's at the threshold for operator error when reading the hydrometer.

If it makes you feel better, you can just add an extra tenth of a percent to your notes.

2) There are far too many steps along the way between OG and FG to make FG estimates more than just a WAG. I know what attenuation I expect for a given set of parameters, and use that as my target, although I'm usually brewing Belgian styles with lots of simple sugars.

My "normal" beers with just grain usually end up pretty close to the FG estimate I get from Beersmith.

In the end, the software is better than nothing, and will probably get you close, but don't expect it to be perfect.

 

[Stevedkiwi]

Tks for the reply.

strange, most of what I have read suggests abv will increase by about .4 % due to priming. I'll have to do some maths and work it out for myself just to satisfy my curiosity.

Wrt the low fermenatbility sugars, I still reckon that a piece of software ought to be able to cope with this accurately, its just maths after all. I especially think that lactose and M/dextrine ought to treated the same way.

Looks like I'll be using the Australian developed (and free) kit and extract spreadsheet which copes with all of the above seamlessly and acurately, at least until (If) I start doing all grain.

Steve D