I struggled how to measure correct alcohol content for my gin.
Situation:
I have distilled gin with a base of 96% alcohol and after distilling I still have 96% alcohol - so far so good. But now I add fresh rhubarb to the 96% alcohol and let to soak for a while. I want to dilute my gin to 42% but here I struggle as my tools don't work any more and suspect the sugar in the rhubarb to mess with me (even the sugar content in rhubarb are very small). I have tried different Alcohol meters and a reflector meter but none of them give me confidence I get the right numbers. I have looked at hydrometer but it does not seems to do the job.
Any one that can help to explain how to measure the right alcohol content?
You’ve got to measure the volumes. Alcohol is %ABV, or “alcohol by volume”. Adding syrup adds volume. But you haven’t added alcohol. So, the %ABV goes down because the total volume is increased.
For example:
1) start with 1 liter of 50%ABV (100 proof) neutral is 0.50 x 1000ml = 500ml of (theoretically pure) alcohol.
2) add 500ml of syrup results in 500 + 1000 = 1500ml of spirit.
3) the “calculated” proof is then 500ml / 1500ml = 33.33%ABV, or 67 proof.
The Proof & Traille hydrometer only measures the density of your spirit and represents the change in density with respect to alcohol and water. If you add something other than that, the density will be askew, like the sugar water solution.
So, you can only “calculate” the modified spirit’s alcohol concentration by measuring the volumes given the unmodified solution’s “measured” density.
If you NEED more accuracy than that, then you’ll have to go to a laboratory that can measure the gas spectography (the color/temperature of the flame when burned). But I doubt that it is economical or even justifiable for a hobbiest.
ss
still_stirrin wrote: ↑Tue Jul 21, 2020 1:13 pm
You’ve got to measure the volumes. Alcohol is %ABV, or “alcohol by volume”. Adding syrup adds volume. But you haven’t added alcohol. So, the %ABV goes down because the total volume is increased.
For example:
1) start with 1 liter of 50%ABV (100 proof) neutral is 0.50 x 1000ml = 500ml of (theoretically pure) alcohol.
2) add 500ml of syrup results in 500 + 1000 = 1500ml of spirit.
3) the “calculated” proof is then 500ml / 1500ml = 33.33%ABV, or 67 proof.
The Proof & Traille hydrometer only measures the density of your spirit and represents the change in density with respect to alcohol and water. If you add something other than that, the density will be askew, like the sugar water solution.
So, you can only “calculate” the modified spirit’s alcohol concentration by measuring the volumes given the unmodified solution’s “measured” density.
If you NEED more accuracy than that, then you’ll have to go to a laboratory that can measure the gas spectography (the color/temperature of the flame when burned). But I doubt that it is economical or even justifiable for a hobbiest.
ss
That is indeed a smart way to calculate %ABV when one adds a sirup to a alcoholsolution.
But when one macerates fruit or vegetables in an alcoholic solution, alcohol migrates into the fruits and water plus flavory substances migrates into the alcohol. So when one filtrates the fruit out of the mixture, its takes some alcohol with it and leaves some water behind. Both of unknown quantities.
Which means your calculation does not work any more.
In this kind of mixtures one can not measure alcohol content in a simple way.
One can determine alcohol content. For example by completely distilling a well measured sample of maybe by gas chromatography.
Estimate the volume of water and sugar in the fruit using Google and/or your refractometer.
Calculate the abv of all of the liquid in the steep.
Given enough time, the alcohol and sugar will reach equilibrium in the liquor and the fruit and will be close to the abv% that you calculated.
and for a start try the volume calculation.