Does anyone have a table, tool, or formulae that allows them to calculate alcohol and remaining sugar - assuming you know the original specific gravity and the current? We all have tables to calculate the final alcohol assuming the wine is dry - but what about interim clculations? I would like to be able to track both alcohol and redsidual sugar as fermentation progresses. Anyone have any such a tool?
Referring to the Lum Eisenman "The Home Winemakers Manual" the only way to do it is to use a clinitest from the drugstore. You can download the PDF of the manual online it tells how to do the test in detail.
Haven't seen an explicit formula for this, but you can certainly guesstimate this pretty easily, using for example info from Ben Rotter's site:
under Calculation -> Hydrometer/Sugar/Alcohol Tables
Just remember to take into account the fact that dry wines end up somewhere around 0.990-0.993. And when you're getting close to dryness, Clinitest will give you more precise RS values as Walter already mentioned.
Pp
This is not as straight forward as you might think but there are equations and tables out there that profess to do more or less what you want. Unfortunately, no one seems to be able to say exactly which formulation should be used in what way.
C.J.J. Berry, in "First Steps in Winemaking", has a table that gives the expected alcohol yield if you ferment to a SG of 1.000. Duncan and Acton's book "Progressive Winemaking" is a more scholarly book (translated more difficult to read) that covers this in greater detail and gives a table based on fermenting out all of the sugar. Both give formulae for calculating intermediate and extrapolated alcohol yield based on their tables. Both of these authors should be considered reputable. You will find the table published by Barry reproduced in other texts but I have never seen Duncan and Acton's table published elsewhere.
Things get confused when you find the same table published by Barry but with the alcohol yield column labeled for fermentation to absolute dryness rather than to SG=1.000. Something is wrong but I have never found the source for either definition nor have I found raw data that would support either. Duncan and Acton seem to claim their table is based on empirical measurements. The other tables are just published without qualification or source.
Several years ago I set out to determine which table was correct. I could not definitively show which should be used. I was able to show that Duncan and Acton's table is consistent with Barry's, hence I have used those definitions.
This is not insignificant. The table you use can change your determined alcohol calculation by 1 to 1.5% or more. I did publish my finding in Winemaker Magazine and I could send you a copy if you would like.
In fairness I will say that one person who contributes on this site, and with whom I usually agree, took extreme exception to my findings but never could produce any references that would show that his beliefs were more correct than mine. I do not want to open that disagreement again!
Anyway, using the equations in the article you can predict what your final SG will be and you can determing the residual sugar in terms of gravity units. Or you can determine residual sugar using the clinitest. Either should be considered relative.
Ray
I would agree with Ray that there are too many variables but if you are only looking for approximations just use the PA scale and subtract one from the other to get the alcohol level, brix is sugar remaining more or less. Dissolved solids are mostly sugar and acid.
Joe
Yup......... ;o)
DrinksForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.