What is your strategy for getting accurate hydrometer readings, not distorted by other density changes beyond fermentation?

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steffeeh

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I crush my fruit, add pectic enzymes and wait 24h, add the syrup and stir it up, then take the original gravity reading, add yeast and macerate, press it out and move on to secondary fermentation, then at the end of secondary take the final gravity reading and calculate the ABV.
But then I won't have factored in the pulp leeching out juices during maceration with the help of the pectic enzymes and the fermentation breaking down the fruit, neither will I have factored in the extra juices from when I press and move to secondary - all of which have a different density than the sugar water mixture (with minimal fruit juice from the crushing) that I used to calculate my original gravity from in the beginning. As more juice gets into the must the amount of liquid will increase as the amount of pulp decrease, and the lower density in the fruit juice in comparison to the must it's leeching out into will pull down the density, distorting any gravity reading. Because if this, unless I have a good strategy to factor in all of this, my calculated ABV won't be the actual ABV, but probably lower (10% instead of 13% for instance).

What is a good strategy to factor in all of this to get an accurate ABV in the end? I have made my own strategy where I keep track of the amount of actual liquid as well as the specific gravity and do a lot of calculations for each major step so that I can factor in the dilution and more (very long story made short) - however this can feel a bit math-tedious and I suspect that I might still be missing something and still getting an inaccurate ABV.
 

bernardsmith

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Hi Steffeeh and welcome.
Not sure there is a "good strategy" to get an "accurate" reading. I use my hydrometer to get a good enough estimate of the potential and actual alcohol content of my wines and meads. After all you are not in fact measuring the alcohol content but measuring the density of the liquid and using the density as an algorithm for the ABV.
I use USDA data on the sugar content of the fruits I use (although I could use a refractometer to give me another approximation of the sugar content of the fruit). I know how much water and sugar I add and I know approximately how much each pound of added sugar will increase the density of the water. I measure the total volume of the liquid and so when I take a gravity reading I have a fairly good sense of whether I am fermenting a must at 1.090 or 1.100 or whatever.
I am not someone who is subject to any taxation or duty regulations so my measurements are really to help me ensure that my fermentations are set up to make the kinds of wines I want to make and the fermentations are progressing and ending where I want them to be.
A wine made at 12% ABV is basically the same as one at 11% or 13%. which is going to be very different from one I make at 5 -7%. (cider). SG and ABV are approximations. And most approximations, if you know what you are doing are "good enough". There are ways to very accurately measure the ABV of your wine but they involve a fair bit of technology and cost ($$$) and if you don't need such accuracy then it is a little hard to see the value of spending a great deal of time and effort in trying to obtain a more accurate estimation than one that is in fact quite limited by the tools we use to measure the sugar content of a liqquid and then the alsohol content when we are measuring neither the actual amount of sugar in solution or the actual volume of alcohol in solution.
 
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