AndyS, Vince, or anyone else with a refractometer:
Here's an example brew: What's the extraction?
Brew Water: 252.2g Dry Coffee: 23.9g
After brewing: Filter gains 2.4g of coffee Wet Coffee Puck: 57.2g Coffee Produced: 215.4g
(calculated loss is (252.2+23.9)-2.4-57.2-215.4 = 1.1g unaccounted for)
Measured strength at initial pour (215.4g) = 1.93% (at 19.8°C)
I put the sample back and diluted to 367.9g of total coffee, measured the strength at 1.13% (at 20.3°C).
Comments?
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
So now, here's same bean, attempting same brewing parameters (grind, brew water, temperature, etc, same PARALLEL device (so starting with same temperature):
Brew Water: 252.3g Dry Coffee: 23.9g
After brewing: Filter gains 2.2g of coffee Wet Coffee Puck: 72.3g Coffee Produced: 199.5g
(calculated loss is (252.3+23.9)-2.2-72.3-199.5 = 2.2g unaccounted for)
Measured strength at initial pour (199.5g) = 1.93-1.94% (at 19.8°C)
I put the sample back, knowing what the strength was, and diluted to a target of 340.0g of total coffee (but overshot and got 342.7g), and measured the strength at 1.13% (at 19.9°C).
NOW what's the extraction?
This is the same coffee, ground at the same time in the same batch, attempted same brewing parameters, same batch of water, same brewing times within seconds, fresh filters used exactly the same way, pressed into two same style mugs, just a little difference in how hard I pressed the puck.
((.0194X199.5) / 23.9 X = 16.2% extraction?
NEITHER cup is underextracted by any stretch of the imagination. In fact, these two cups of coffee are INDISTINGUISHABLE. They taste pretty darn good.
It was puzzling, so I thought I'd go ahead and try to overextract, again.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Been there, done that. Few times with slight variations in brews. I was checking the ending press pressure effects. I was also verifying what AndyS had found earlier.
For any given single brew, the first two thirds is essentially the same strength as the last third Even if I REALLY press hard and shake the drops off of the cap in the last third. If I stop short and press the last 20ml into another cup, for all practical purposes even this is the same strength as the rest of the coffee.
I think I can conclude from this that the solution concentration IN the brew mass is the same strength throughout the brew mass. The AP (the way I use it) is an immersion brew method.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
So, now I've got two brews, done the same way as much as I can possibly duplicate, end results are same strength but different produced volume.
If I can duplicate strength that consistently with the same amount of coffee, the produced volume should not affect the percent extraction.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
I recently did an immersion brew at 21% brew ratio. Just under half the water was retained in the grounds. The standard way of calculating extraction is just solids in the cup divided by initial coffee and this resulted in a value of 12.3%. This was a hot brew that was left on the grounds for many hours and it sure didn't taste underextracted.
But suppose all of the liquid in the grounds was included in the calculation? Then the extraction would be given by:
s = strength c = initial coffee mass mc = mass in cup mf = mass in filter mp = mass of puck
In the case of my brew the adjusted extraction is 23.5%.
For Netphilosopher's brews, the adjusted extractions are 20.7% and 20.6%, respectively.
For an apples to apples comparison with other brews it probably makes sense to pretend that some "typical" fraction of the liquid in the puck is not part of the extracted solids.
I recently did an immersion brew at 21% brew ratio. Just under half the water was retained in the grounds. The standard way of calculating extraction is just solids in the cup divided by initial coffee and this resulted in a value of 12.3%. This was a hot brew that was left on the grounds for many hours and it sure didn't taste underextracted.
But suppose all of the liquid in the grounds was included in the calculation? Then the extraction would be given by:
s = strength c = initial coffee mass mc = mass in cup mf = mass in filter mp = mass of puck
In the case of my brew the adjusted extraction is 23.5%.
For Netphilosopher's brews, the adjusted extractions are 20.7% and 20.6%, respectively.
For an apples to apples comparison with other brews it probably makes sense to pretend that some "typical" fraction of the liquid in the puck is not part of the extracted solids.
Yep. Working on recalculating my other brew data to see if this has a better correlation to taste.
I just did an 8:00 inverted preheated AP brew, slightly finer grind, stepped the water in every minute (about 1/8 of remaining) while stirring, and reheating to boiling between each step of adding the brew water.
Brew Water: 258.2g Dry Coffee: 23.8g
After brewing: Filter gains 1.9g of coffee Wet Coffee Puck: 55.1g Coffee Produced: 224g
(calculated loss is (258.2 + 23.8)-1.9-55.1-224 = 1g unaccounted for)
Measured strength at initial pour (224g) = 1.94% I put the sample back and diluted to 384.9g of total coffee, measured the strength at 1.13%
By taste, this stuff was OBVIOUSLY not underextracted - I would have said it was highly to borderline overextracted, but not as bad as I expected since I used a slightly finer grind and I brewed the thing at a really long contact time.
The calculated extraction was 18.3%, but using the brew mass technique, it's more like 21%.
I still think my VSTcr is reading about 3-6% low consistently. I'll have to break down and buy the calibration fluid, I suppose.
I think also I'll have to start a new thread on some fun things I've been doing with coffee samples, the VST filters, some dehydration, and centrifugation. I knew I'd find a use for my old centrifuge... ;^D
Pure coffee oil tastes REALLY harsh and takes a long time for the taste to go away, just in case anyone is interested.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
I don't know if you remember in the old Aeropress thread where Alan Adler was doing what we're talking about. AndyS reprimanded him for using a non-standard extraction value in order to fluff up his results. I always thought that was an interesting exchange. We use the idea of extraction in two ways.
If you brew perfect coffee but spill half of it does the extraction go down by 50%?
In one sense it does, but the balance of extracted components doesn't change. The problem is that we use extraction as a proxy for this balance since we have no other simple means for measuring it (other than our senses). So the two ideas, one about economics and the other about balance, are conflated.
I don't know if you remember in the old Aeropress thread where Alan Adler was doing what we're talking about. AndyS reprimanded him for using a non-standard extraction value in order to fluff up his results. I always thought that was an interesting exchange. We use the idea of extraction in two ways.
If you brew perfect coffee but spill half of it does the extraction go down by 50%?
In one sense it does, but the balance of extracted components doesn't change. The problem is that we use extraction as a proxy for this balance since we have no other simple means for measuring it (other than our senses). So the two ideas, one about economics and the other about balance, are conflated.
The issue is that calculation of extraction is blown out of the water because of HOW extraction was developed. If you look at the old brew charts, extraction was determined by a specified grind, with a specified method (drip, a wash method), and then it's assumed that the spent coffee has gravity drained all that can be gotten from the grounds.
But if I brew with a Melitta BCM-4C drip machine, grind a bit finer, I can get a particular strength BUT then I can get another several ml out of the coffee if I were to simply grab the filter and squeeze it. But, because it's a wash method of brewing, the strength of these squeezings isn't the same as the strength of the bulk of the coffee produced.
The brew mass calculation also breaks down with espresso (which is both a wash method AND you don't know how much water went IN to your end result - you would have to diligently weigh the dry coffee, the wet spent grounds, and the produced amount of espresso, and then assume that the total brew mass is the wet coffee plus the produced espresso).
7 or 8 brews so far, and the first 2/3 of the coffee are the same strength as the last for the immersion methods. However, I do notice that different coffees and different contact times and different grinds, and maybe even the brew ratio seem to have the potential to affect absorption of liquid in the puck. My intuition is that the absorption is "coffee" but maybe that's not the case.
I think that the answer is somewhere closer to assuming the majority of the liquid in the brew mass is "coffee" at the same strength as the stuff produced, but maybe not 100%.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
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