[some things in here are incorrect and I am due to edit this. we aren't finding specific gravity, we are finding density and there is a difference. density can be converted to specific gravity but gravity (9.8 m/s/s) has to be factored in and I never learned exactly how though I think I remember circular 440 explaining it. even still you will find invaluable ideas here. a friend had told me we use hydrometers because they can add more significant digits than measuring density and using a known value for gravity which doesn't have a lot of significant digits, but I never learned more than that.]
Slowly I am either relearning or finally learning-to-apply all my high school chemistry and physics. professor G. would be in disbelief I’ve come this far.
Recently I was checking my blog analytics and noticed someone clicked on an article I linked to back during my nut milk phase. I followed the link because I didn’t remember where it went and something finally dawned on me: maybe we don’t need hydrometers to find the sugar content of commercial liqueurs. Maybe all we need is a kitchen scale and some charts.
The linked post on milk by Alicia Noelle Jones used a kitchen scale to measure the density of milk by noting the high school lesson that density is just mass / volume. She found the mass of the milk with her kitchen scale, measured the volume, then did some division. Alicia used kilo grams per meter cubed (kg/m^3) but I prefer grams per liter (g/l). This handy calculator can help make some conversions such as converting g/l to a more useful specific gravity. The specific gravity of water is one thousand grams per one liter. Sugar is more dense than water and alcohol is less dense.
Once you have the specific gravity and the alcohol content from the label, a sugar content can be calculated. This has been demonstrated in other posts but should be updated. (will do later. I wrote something for a book I never published on the blog…)
So what does this really simple kitchen scale method solve?
– Often times we will want to measure either the alcohol content of spirits or the sugar content of a spirit with a known alcohol content. we may even use it to keep kitchen recipes consistent. density of a soup or veal stock anyone?
– Accurate narrow range hydrometers are expensive and fragile.
– Often times sample volume sizes are not enough to float a hydrometer, especially when trying to measure the alcohol content of segmented distillation runs.
– It is just one less tool. We have kitchen scales at work but I do not keep a hydrometer. you just cannot trust glass in our kitchen.
– This method can also be used to measure the sugar content of fruit juices to help raise the sugar content to a precise measure. Some bar programs may have wanted to explore my ice wine grenadine recipe but were daunted by the $70 refractometer I used to always keep my sugar content at a precise 400 g/l.
– Many people out in the middle of nowhere can help with liquor archaeology. Do you have an old bottle of amer picon? Note the alcohol content, weight a sample and measure the volume and I will help you estimate the sugar content to help others make more accurate reproductions.
After discovering a kitchen scale can measure carbonation, we’ve now discovered it can also measure specific gravity. Hopefully this might help some people justify the expense of great models. cheers!
One more idea that might be useful to bars is quickly estimating the dissolved volume of a weighed portion of sucrose. The density of sucrose relative to water will help us estimate this. water has a density of 1.0 g/cm^3 while sucrose (white sugar) has a density of 1.587 g/cm^3 making it 1.587 times more dense.
To estimate the dissolved volume of 100 grams of sucrose we simply divide 100 by 1.587 which is 63.01. This is just a low involvement estimate and does not account for other variables like temperature effecting density.
Quickly estimating the dissolve volume of sucrose may help low involvement home liqueur producers make their products compare to their favorite commercial examples. Once the volumetric displacement of the sugar is known a little algebra can help predict what the final alcohol content is going to be as well.