Green Coffee Buying Club
Coffee Discussion boards => Hardware & Equipment => Topic started by: hankua on February 24, 2015, 07:09:39 AM
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I managed to win a new Misco Palm Abbé PA202 on EBay for less than half the retail price. I think it's very similar to the VST meter, a PA203 with custom software and upgraded optics. The 202 has two scales, brix and refractive index.
Anything VST is pretty controversial on coffeegeek but interesting none the less. I found two formulas in one of the threads: TDS=545*nD-726 and in the next paragraph TDS=560*nD-746. The other formula is brix x .85, I think RI is the more accurate scale to use. And it's possible to use other scales, not sure if there relevant; specific gravity?
Question is, has anyone used a digital refractometer with both brix and RI scales?
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I have a refract I use for brewing beer to hit a specific gravity I'm after.
I've never thought about looking at coffee in it.
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you might be able to check if proper water to coffee ratio was achieved?
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My mouth does that. ;)
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My mouth does that. ;)
Hahahaha!!!
But that's not geeky enough. Forget what your palate tells you; you must use a gadget to determine if it's good or not. ;D
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Ok but regardless I bought a cheap Amazon refractometer for like $15 way back when still works amazingly and I wouldn't spend a penny more for what it does. Back when I bought mine they were like $80+ for a domestic product.
Ummm...I might drag mine out to see what the numbers do (http://drinks.seriouseats.com/2013/09/coffee-tools-extraction-refractometer-extract-mojo-coffee-testing-equipment.html)
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Ok but regardless I bought a cheap Amazon refractometer for like $15 way back when still works amazingly and I wouldn't spend a penny more for what it does. Back when I bought mine they were like $80+ for a domestic product.
Ummm...I might drag mine out to see what the numbers do ([url]http://drinks.seriouseats.com/2013/09/coffee-tools-extraction-refractometer-extract-mojo-coffee-testing-equipment.html[/url])
How did you use the results?
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I have a refract I use for brewing beer to hit a specific gravity I'm after.
I've never thought about looking at coffee in it.
We use densitometers and beer analyzers at work that read SG, ASBC Balling, and Plato balling. Beer results are always reported using the Plato scale.
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densiometer? Is that to measure when someone on the board gives a really obtuse answer to something? :D
Aaron
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Well I took a stab at this and ran a sample from the office coffee pot. Got 1.3348 nD unfiltered and 1.3348 nD paper filtered (lab quality). I'm confused why there are two different formulas in the same coffeegeek post. If my math is correct it worked out to 1.466 and 1.488 tds.
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I also have tds meters...you just stick it in the fluid and it gives you a digital tds reading.
Are they giving you some sort of equation/formula to use a refractometer to calculate tds?
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I also have tds meters...you just stick it in the fluid and it gives you a digital tds reading.
Are they giving you some sort of equation/formula to use a refractometer to calculate tds?
Not really, I found a formula on coffeegeek. Refractive index is supposed to be the most accurate method other than drying out the coffee sample. Maybe I should try drying out a sample and compare it to the digital refractometer?
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I've never heard of that before but it's interesting.
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Good discussion going on coffeegeek
http://coffeegeek.com/forums/coffee/machines/682443?LastView=1424872230&Page=7 (http://coffeegeek.com/forums/coffee/machines/682443?LastView=1424872230&Page=7)
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If you do wind up testing digital TDC meter vs the refractometer equation vs drying out samples let us know what you find out.
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I could try out the drying method; but just exactly what is it?
Say for instance dry out 10g of brewed coffee and weigh it out after finished?
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Yeah that's what I don't really understand.
Seems like the tds meter is the best fastest cheapest way to measure tds.
And refractometer to measure brix/plato.
Once you dry out a sample I'm not sure all what evaporated, what didn't, and what our how you would even measure it.
I'm curious about it but ultimately really do prefer my taste decide for me rather than gold cup standards. I'd probably find brix useful at the estate grading crops but I'm still unsure about usefulness in my kitchen. Still it's interesting.
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John, don't quote me and I am sure one of our professional chemists will hopefully correct me but Id think that everything left after drying is the 'solid' part of Total Dissolved Solids. Otherwise I think it'd be classified as VOC Volatile Organic Coumpound (may evaporate) or otherwise.
Heres the thing, do you give it a good stirring and test it or let it set for half an hour, an hour or 12 hours for some of the suspended solids to settle to the bottom ie the mud? How does this affect your TDS then? What are we going to use as a control?
Aaron
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I'm thinking the same thing about dissolved solids vs dehydrated solids but I haven't read the CG threads to see what they are doing.