BrewSpook

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As a 30 year old electrical engineering student, I am afforded several things above my 19-20 year old counter parts that force me to ask some serious questions...

The latest being - does beer have a resistive property? My thought being that as the sugar is used during fermentation the conductive property, specifically the impedance of the liquid would change. This would allow for measurements to be taken and some sort of conversion to a SG reading that could be monitored by electric probe.

Has anyone read anything about this?

Initial experiment thoughts would be 1 lb DME in 1gal H2O, lightly hopped and take measurements before and at many points during fermentation matched with hydrometer/refractometer readings and see if there is a potential for relativity between the two.

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mattd2

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Do it!
Would be very interesting to find out more about this. Check out some of the aquerium forums for DIY stuff on conductivity probes, etc.
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mendnwngs

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I've spent a few years working the pharma angle.. Making water to USP standards (DI, or 18 megohm water)

Salts tend to be the big effector for resistance, in my experience.. But... I have no info one way or the other regarding sugars, so I too would be curious.

I would think that in order for a resistive measurement system to work tho, the user would have to measure the resistivity of the source water (after any salts / buffers / gypsum / water additions have been added, and thoroughly dissolved.) to get a baseline reading, and to calibrate for the batch..

But, I could be wrong..

You could build a rig that holds the probes a set distance apart (say 1 cm) then test resistivity of the source water. Then test a wort pre-biol, and post-boil to see if you get different results..

If you do, then perhaps a controlled experiment making a (say 1lb DME in 1 gal water) vs smaller, or larger quantities in the same water source to see if the probe scales readings in a meaningful way.

Sorry if i'm rambling.. Too many homebrews

-Jason

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BrewBeemer

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I would bet any variation in ph alone would have a greater effect on your conductivity readings than the wort sugar content change.
I've done past testing with the Koi pond water from clean to dirty time to change the water. The ph alone overpowered any readings of importance I was looking for. No plans of making candied Koi.

mattd2

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The other thing for using this for fermentation monitoring is if the alcohol will effect the resistance/conductivity. But if you could get a menaingful results from experimental data it would be worth it. Even if you can't reach an empherical (is that the right word ) formula, if it gives stable readings you could still use it to determine if fermentation is complete (no change in reading over a few days)