Posted Mon Feb 25, 2013, 10:48am Subject: Espro and Brix Meter
I am trying to dial in my brew via my Large Espro Press , this question is particularly about measuring a Espro Press Pot brew with an Atago Pal-1.
I bought the Atago Pal-1 after reading about here on this website and found one for $150. It seams to work better than an optical meter, TDS meter, and much more convenient then heating up the spent grounds.
I have had moderate success dialing in my Aeropress coffee production (concentrate and full strength press) with the Pal-1 and converting to TDS with formula (brix x 85A% = TDS%) as discussed all over the board there are a few acceptable ways to measure amount to multiple by TDS% to get bean that is extracted in brew.
I use: Brew water - 2.08 x Beans, but I also look at what my extraction ratio is with (brew water x tds%)/ beans = extraction % (Per Alan Alder)
On to the Espro, I am wondering if the Pal-1 brix meter can even work. It seams every variable I move around, delivers 1.2 or 1.3 with no rhyme or reason why. So that is a weak cup of coffee (1.02%), but it taste good and full bodied....without the fines (signature of the Espro). So I thought, if I could find a way to get a little more of the bean dissolved it may taste even better.
My base coffee is 45g of beans (17x) with 765g water @ 200 for 4 minutes, Course 2 on Capresso Infinity (based on linear interpolation is 880 microns avg). I have gone 6 minutes, I have lowered the water (16x @ 4mins), I have changed the number of times I stir....no change in Pal-1 Brix Meter.
I enjoyed my read of Scott Rao's Everything But Espresso, in the appendix he highlights that he is able to achieve great strength and extraction from upwards 18x, mix, so I wondering why the brix meter is off.
Has anyone else experienced this with this device or similar? I am tired of spinning my wheels.
jpender Senior Member Joined: 11 Jul 2011 Posts: 401 Location: California Expertise: I like coffee
Grinder: Kyocera CM-50 Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Mon Feb 25, 2013, 3:08pm Subject: Re: Espro and Brix Meter
sammyjankis Said:
I am trying to dial in my brew via my Large Espro Press , this question is particularly about measuring a Espro Press Pot brew with an Atago Pal-1.
I bought the Atago Pal-1 after reading about here on this website and found one for $150. It seams to work better than an optical meter, TDS meter, and much more convenient then heating up the spent grounds.
I have had moderate success dialing in my Aeropress coffee production (concentrate and full strength press) with the Pal-1 and converting to TDS with formula (brix x 85A% = TDS%) as discussed all over the board there are a few acceptable ways to measure amount to multiple by TDS% to get bean that is extracted in brew.
I use: Brew water - 2.08 x Beans, but I also look at what my extraction ratio is with (brew water x tds%)/ beans = extraction % (Per Alan Alder)
On to the Espro, I am wondering if the Pal-1 brix meter can even work. It seams every variable I move around, delivers 1.2 or 1.3 with no rhyme or reason why. So that is a weak cup of coffee (1.02%), but it taste good and full bodied....without the fines (signature of the Espro). So I thought, if I could find a way to get a little more of the bean dissolved it may taste even better.
My base coffee is 45g of beans (17x) with 765g water @ 200 for 4 minutes, Course 2 on Capresso Infinity (based on linear interpolation is 880 microns avg). I have gone 6 minutes, I have lowered the water (16x @ 4mins), I have changed the number of times I stir....no change in Pal-1 Brix Meter.
I enjoyed my read of Scott Rao's Everything But Espresso, in the appendix he highlights that he is able to achieve great strength and extraction from upwards 18x, mix, so I wondering why the brix meter is off.
Has anyone else experienced this with this device or similar? I am tired of spinning my wheels.
The stated accuracy is ±0.2% Brix so I think for normal strength coffee the percent extraction you calculate with this meter won't be very precise.
With a 45g/765g coffee/water recipe and 20% extraction the strength should be 1.2% TDS. Assuming the 0.85 %TDS/Brix factor is correct, your meter is telling you that your coffee is 1.1±0.2% TDS. This in turn means that your extraction is 18.9±1.7%, i.e., somewhere between 17.2% and 20.6%.
edit: The reason this doesn't match the chart in the appendix of Scott Rao's book is because that chart is for the original method of calculating extraction yield. That method is appropriate for a drip coffee, but for an immersion brew (like the Espro) the extraction should take into account the dissolved solids trapped in the grounds. If you use the original method you usually get an extraction a couple of percent lower. That would put you off of Scott's chart.
The bottom line is that you need more coffee to get the same strength and quantity in the cup with an immersion method versus a percolation method. So add some more coffee if you want it stronger. The formula relating strength and water/coffee ratio for immersion brewing goes like this:
r = e*(1-s)/s, where r=water/coffee ratio, e=% immersion extraction, and s=%TDS
So, for example, if you want 1.3% TDS and hope to extract at 20%, your water/coffee ratio should be about 15x.
Posted Tue Feb 26, 2013, 11:04am Subject: Re: Espro and Brix Meter
Your formula says that I can tease up extraction rate, but not dissolved solids at a 17x by extending extraction, grinding finer, increasing water temp, agitation. I thought the relationship was more linear than that, more extraction = higher TDS.
jpender Senior Member Joined: 11 Jul 2011 Posts: 401 Location: California Expertise: I like coffee
Grinder: Kyocera CM-50 Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Tue Feb 26, 2013, 12:46pm Subject: Re: Espro and Brix Meter
sammyjankis Said:
Your formula says that I can tease up extraction rate, but not dissolved solids at a 17x by extending extraction, grinding finer, increasing water temp, agitation. I thought the relationship was more linear than that, more extraction = higher TDS.
It IS very nearly linear. You can approximate it with s=e*(1/r) in which case it is exactly linear. The difference is minor, only about 0.02% TDS higher for the circumstance you are interested in, so you could ignore the correction without harm.
If by grinding finer, using hotter water and longer steep times you increase the extraction by 2% you should see a 0.1% change in the refractometer reading. But since your refractometer isn't very sensitive it may be difficult to actually discern this change. This is the reason to spend $500 on a VST refractometer. It's an order of magnitude more sensitive than the Pal-1.
I don't have anything at my fingertips. Search for "immersion extraction" and see what you find first.
The basic notion isn't terribly complicated. With drip coffee you rinse the grounds with water so extraction is a measure of what is in the cup. But with an immersion brew the grounds are drained/pressed and not rinsed. So the liquid in the grounds contains dissolved coffee that really needs to be counted in the extraction. That's why you use brew water mass instead of beverage mass. And while the beverage mass includes the dissolved solids, the brew water mass does not; this is where the 1/(1-s) term originates.
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