# Coffee and Espresso refractometers



## CoffeeChris (Dec 2, 2011)

Struggling to find one online as theres different ones for different uses...?


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## jimbow (Oct 13, 2011)

HasBean sell lab refractometers designed for coffee and to be used with the VST Mojo apps. Most other refractometers measure either in nD (refractive index) or are calibrated against other scales for specific purposes e.g. Brix for measuring sugar solutions. These other scales can be converted to coffee TDS but such conversions carry inaccuracies.

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## CoffeeChris (Dec 2, 2011)

Thanks.. I had seen one on ebay, shipped from america. Think it was around £200. I guess Im best to stay away from that then....They are not cheap!


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## CoffeeChris (Dec 2, 2011)

Forgot to ask. Is there any other way to scientifically measure?


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## MikeHag (Mar 13, 2011)

Yes. The SCAA Coffee Brewing Handbook lists:

a. Oven-dehydration

b. Coffee hydrometer

c. Direct-reading Hydrometer

d. Conductivity Meter

I don't think any of them offer the combination of practicality and accuracy that something like a dedicated coffee/espresso refractometer provides though.


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## MWJB (Feb 28, 2012)

Would it not be feasible to measure & calculate extraction yeild...if scales were accurate enough? I'm thinking more about brewed methods (Aeropress/Clever Dripper) more than espresso (unless you have the facility to control the g of water added).

I'm thinking weigh brewer, filter & grounds (all dry). Weigh water added.

When the extraction is over, re-weigh brewer, filter & wet grinds - anything over the initial dry weight is retained water. Subtract this from water added.

Any difference between the result of the last calculation (excess over the remainder, after subtracting 'retention' from 'water added') & the weight of the final brew, must be the extraction yeild?

E.g. If you had an Aeropress brew added 230g water to 14g of grounds, then found the wet brewer brewer was 27.56g heavier after extraction, due to retained water - you should then have 202.44g of beverage. But if you had say 205g of beverage, you have collected another 2.56g along the way...2.56g/14g = 18.3 extraction yeild? 2.56/205g = 1.25% TDS?

This leads me to think....I need some bigger scales!


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## MWJB (Feb 28, 2012)

Answering my own question...simple weight comprisons can't distinguish between dissolved & undissolved solids, so "No".


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## lookseehear (Jul 16, 2010)

Conservation of mass innit!


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## jimbow (Oct 13, 2011)

Also bear in mind fluids will weigh different amounts at different temperatures.


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## CoffeeChris (Dec 2, 2011)

Have noticed via twitter that John Gorden uses this. http://www.ebay.co.uk/itm/Hanna-Dist-1-TDS-PPM-Hydroponic-Solution-Tester-/260504725022 Is this the same kind of thing as VST STANDARD COFFEE REFRACTOMETER that Hasbean sells?


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## MikeHag (Mar 13, 2011)

No. He uses that to measure his water. It isn't able to measure coffee with sufficient accuracy. The Coffee Refractometer measures Brewed Coffee and Espresso.


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