Hello,
I want to calculate alcohol leven in wine to my degree work and i don’t know how can I do this.
My first idea, I use condutivity sensor to calculate it but I think it doesn’t work
The second idea, I use hydrometer or maybe I can calculate it by PH level.
If you have any idea please help me.
I don’t think anyone does, short of using a mass spectrometer or an absorption spectrometer. Or maybe distilling of just the ethanol alcohol out of it.
Hydrometer
This is
[quote] hydrometer is an instrument used for measuring the relative density of liquids based on the concept of buoyancy
[/quote]
That will not, as such, measure the alcohol content but it could be inferred from a measure before and after the fermentation process.
My mentor told to me another idea. Maybe I can calculate by pressure sensor.
Did your mentor talk about a pressure sensor or a weight sensor? For the weight sensor I have an idea.
Hi,
A quick Goolge;
how to calculate alcohol percentage in wine?
Gives some methods, including hydrometer, but as @Grumpy_Mike has pointed out its a before and after measurement, not an absolute.
Tom... 
He talked about both of them.
What's the idea behind the pressure sensor, that the amount of gas released and hence the pressure would indicate how far the fermentation had progressed? I've never made wine, but did home brew beer for a while, and as I recall the vat vented to the atmosphere anyway (through a water trap to stop outside air getting in).
My mentor said he was sure he could be calculated from it just to look after it, but he didn't say anything specific.
The hydrometer gives an absolute measurement of specific weight in weight/volume. The Wikipedia article only points out that you can apply this measurement before and after the fermentation. It is not a relative measurement.
This value measured with a hydrometer is suited to determine the content of alcohol, preconditioned that there are no other subtances present like sugar.
What is your exact task? What is the topic of your degree work? Do you have to use an arduino? Has the measurement to be fully automatically?
You might want to read this
My work's topic is android application development so after the measurements I want to generate a QR code which you can scan with you phone and you can save the data in your phone.
The concept was that the device should be placed in a place where there is no internet access and you have to use the phone. The wine cellar is just such a place. I came to the conclusion that here only the alcohol level, temperature and abbot could be measured which can be useful.
To determine the specific weight you need to know the weight and the volume of the wine. For the weight you use a scale, for the volume you have at least two options: 1) a measuring cylinder 2) You drop a defined volume, suspended by a thread, int the glass of wine and measure the increase of weight.
Does that solve your problem? And if not, why not.
BTW, what is abbot in that context?
You can get a good approximation of the alcohol concentration, with some experience, just by drinking some.
Here is a more scientific method but, for your purposes, not very practical:
A typical home brewer will measure the "potential alcohol" immediately prior to starting the fermentation process by using a hydrometer or refractometer (both will have "outputs" of specific gravity and potential alcohol or brix or...). At that time, the potential alcohol is the approximate maximum possible alcohol content after complete fermentation. The potential alcohol can be measure after fermentation begins; at that point, the decrease in potential alcohol from the initial value gives an indication of the current state of affairs. Whether that is what the OP is interested in, or whether Arduino-compatible digital sensors are available, I don't know.
conductivity measures dissolved salts. ethanol is not a salt at normal pH values, so this is no use.
This is how dissolved sugar is measured, using the density change. Ethanol has a minor effect too but you cannot separate the sugar and ethanol components.
pH depends primarily on the acids present, so again isn't useful.
Measuring alcohol is normally not done. The initial level of sugar before fermentation is used as a proxy. Or more correctly the drop in density from before and after fermentation measures the sugar consumed to make the alcohol.
For proper analysis, a laboratory would use some form of gas liquid chromatography.
This isn't practical for you.
A pellistor might respond to headspace analysis, but they aren't very specific and you would have to have something in the line to remove everything but ethanol.
I believe the roadside police breath test uses or did use a tube with potassium chromate or dichromate which changed colour if alcohol was in the breath.
The evidential police analysers probably use something more specific, some form of mass spectrometry.
My best guess is that headspace analysis might be an avenue as it gets you away from liquid phase analysis.
Measurements like pH and conductivity won't work as ethanol is non-polar.
There are also possibilities like doing a chemical conversion like oxidation or reduction, say to acetic acid, then you could use pH.
Many analyses use that technique like converting nitrites and nitrates to ammonia which is easy to analyse.
It definitely is polar or it wouldn't be miscible with water. Its just not ionic (not charged) at normal pH values - in strong alkali some percentage can become negative ions, as in sodium and potassium ethoxides, but that's definitely not drinkable(!)
Thanks Mark for being so eagle eyed.
It's decades since I did chemistry but I take your point.
Of course it's water soluble, but it's not like sodium chloride which is easily ionised in water and allows for conductivity measurements.
@DaveEvans
A refractometer does not measure specific gravity but refraction index. This can also be used to determine the sugar content.
Well of course. I didn't say it measures s.g. I said it "outputs" s.g., among other things. E.g., my refractometer has a s.g. scale and a Brix scale. It doesn't have a refraction index scale.
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