With a brewer like the Trifecta MB and the fact that during press-out phase, the air pressure seems to push every last drop of liquid into the cup, would the brew ratio be somewhat less than the +15% adjustment for infusion? Just wondering, because after all the visible liquid has been pressed out into the cup, there is a decent amount of time after that when air pressure is still exerted on the grounds (pump running and drips coming out) and then a final "air puff" that pushes out what little liquid is left under the filter screen. After knocking whatever grounds I can out of the brew chamber, I usually have to use the faucet sprayer to get the remaining grounds out.
The pathologically precise are annoying, but right!
BCM-4C (auto drip) W 450 C 25 R 18 A 1.7 S 0.0125 Y 16.3 P 407.5
E 0.204
AeroPress W 224 C 14 R 16 A 1.3 S 0.0125 Y 14.7 P 205.8
E 0.203 E (Yield) 0.18375
CCD W 400 C 25 R 16 A 2.25 S 0.0125 Y 13.75 P 343.75
E 0.203 E (yield) 0.171875
CCD W 450 C 25 R 18 A 2.25 S 0.0111 Y 15.75 P 393.75
E 0.202 E (yield) 0.174825
French Press W 880 C 55 R 16 A 3 S 0.0125 Y 13 P 715
E 0.203 E (yield) 0.1625
Note that the Absorption differences between an AeroPress, a CCD, and a French Press create a huge error in calculated extraction. Note the difference in strength for the CCD at same brew ratio as the BCM-4C.
This is sacreligious for some, but the brew ratio only controls your strength - you need to use a strong enough brew ratio to get the strength where you like it and avoid weak coffee (which can tip the flavor profile toward sour and acidity, away from body/character/cocoa, etc. Just water down a normal cup of coffee to see what I'm talking about).
Generally, you need sufficient water in contact with ground coffee for about 3-4 minutes for medium grind and 200°F, and about 5 or so minutes for coarse grind and 200°F water. If you grind really fine, you can still achieve extractions around 20% for contact times (including the draindown or press) of around 1 minute or so, but this is extremely difficult to do with very strong brew ratios.
Here's an Espresso double Ristretto (2nd attempt)
Espresso Double Ristretto
C 15 S 0.098 Y 2 P 30 E 0.196
I captured 4.2g of stuff after the shot, then diluted to 10g total with water, and the strength of this concoction was 1.53% - or .153/4.2 = 3.64% when it came out of the machine, or about 37% of the strength of the shot. So the strength of the coffee in the grounds during a full percolation is not exactly zero, but compared to the stuff in the cup, you can treat it as essentially zero.
------------------------------------------ ----------------------------------------- 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
One last thing - I did a dump and drain using my CCD.
Usually, when you do a pourover, the goal is to "rinse" the coffee being produced by slowly introducing new brew water - gradually lowering the concentration in the grounds and rinsing the coffee into the cup.
The strength of the coffee coming out of the dripper will gradually lower over time if this is done properly.
However - dump and drain acts much more like a steep/immersion. You dump all the hot water into the grounds, the strength is fairly high when it comes out, then lowers and then can actually END slightly higher than the strength in the cup. (and, if the grind is too coarse, it will drain out in about 1 minute and you end up with an underdeveloped cup).
I've actually seen this with AeroPress as well - hot water in, stir for 10 seconds, press 1/2 into one cup, press the last into another cup, squeeze the last bits into a third. The strength in each is progressively (but not hugely) stronger each press, with the squeeze and the 2nd half press closer to each other than the 1st half. This just means that I was pressing while the coffee was still in the process of dissolution.
The proper way to do a pourover is to make sure you're using a technique that "rinses" the freshly produced coffee out of the grounds as it is being dissolved.
------------------------------------------ ----------------------------------------- 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 captured 4.2g of stuff after the shot, then diluted to 10g total with water, and the strength of this concoction was 1.53% - or .153/4.2 = 3.64% when it came out of the machine, or about 37% of the strength of the shot. So the strength of the coffee in the grounds during a full percolation is not exactly zero, but compared to the stuff in the cup, you can treat it as essentially zero.
Hang on a second. If absorption is 1.1g/g in espresso, and the retained liquid is 3.64% TDS, then that's 0.6g of extracted solids unaccounted for. That's the difference between 19.6% extraction and 23.6% extraction! Am I wrong?
Hang on a second. If absorption is 1.1g/g in espresso, and the retained liquid is 3.64% TDS, then that's 0.6g of extracted solids unaccounted for. That's the difference between 19.6% extraction and 23.6% extraction! Am I wrong?
I won't comment on the numbers. As jpender has already pointed out, netphilosopher's formulae are not quite the same as those in the talk which is the subject of this thread. However, I certainly do agree with you that the solids dissolved in the water retained in an espresso puck are not essentially zero. What is true, though, is that these solids have been extracted late on and, by ending the shot when you have, you've chosen to keep them out of the cup (these are typically regarded as the undesirable solids). The water in the puck at the end was used to drive the water that came before it through the puck, the fact that it extracted some solids whilst doing so is incidental - and these solids should not be regarded as extracted for the purposes of calculating extraction yield.
Hang on a second. If absorption is 1.1g/g in espresso, and the retained liquid is 3.64% TDS, then that's 0.6g of extracted solids unaccounted for. That's the difference between 19.6% extraction and 23.6% extraction! Am I wrong?
From a technical sense, you are not far off, except the actual amount of solids in the puck for espresso is something less than the calculation. Your original thinking is off because of the assumption that the puck has the same strength throughout.
It's a real pain, and in a shop (because I don't work with anyone at home that does manual espresso) it gets to be annoying to the owner and the barista to be asking for the puck and trying to do measurements especially if there's a few customers. LOL
Seriously, though, you can take the puck, split it into an upper and lower half and "cold brew" the halves to determine the approximate concentration. The few times I was able to do this, the lower half is about two to three times the strength of the upper half.
Confused yet?
What this means is the puck in a high-flow-gradient brewing system like espresso is probably less than the 0.6g of extracted solids.
Remember, there's a strong flow of brew water through the puck - at any moment frozen in time, the concentration at the top of the puck is zero (fresh water being forced in under pressure), the bottom of the puck is what is coming out the spout, so one can estimate the amount of total dissolved solids in the puck at about 50% of the strength of the stream.
The key here is the presence of a strong solvent flow gradient, with minimal agitation.
In most pourovers and non-forced percolation methods, or those forced over a longer period of time, there is time for diffusion throughout the grounds. Agitation is also present in pourovers and drip percolation, so the assumption that the strength is the same throughout the grounds is fairly sound and supported by data. I've checked "upper/lower" halves of the grounds in a drip, and within measurement error the strength in a gravity driven percolation method is pretty much the same throughout - even if you stop the extraction 2/3 of the way through.
Here's the interesting thing - there seems to be a strong preference for espresso to be extracted to 19%. In the example I provided, if the 15g is extracted to 19%:
C 15 Y 2 P 30 E 0.19
T = 2.85g (in the cup) S = 0.095
Define F as the ratio of the puck strength to cup strength: F = 37%
Assume A = 1.1
If you assume all of the puck strength is 9.5%*37% or 3.52%, then you're right - extraction would be around 23.7%
However, reality is more like F = 37%/2 (about half) or 18.5%, so the total dissolution (we call extraction) is more like 21.3% - that's with a target of 19% extraction in the espresso cup. People seem to start picking up on espresso bitterness at 20%+ extraction. AndyS has mentioned this, as has Vince, and I've seen it myself - give someone a ristretto extracted to a calculation of 20.5% and they will probably find it starting to taste overextracted.
In the example (same coffee, retention, production, etc.), but 20.25% extraction, and the assumption that the amount in the puck is 1/2 of F:
C 15
Y 2 P 30 E 20.4% in the cup.
T 3.06g in the cup.
S 10.1%
F = 18.5% (half of the stream strength at the end of the pull)
Total dissolution 22.7%. If taken as the control volume over the whole espresso brewing process, it's just overextracted, where you would expect the onset of bitter notes.
This implies that there is probably a reason for a preference of lower extraction for espresso vs. other percolation methods.
------------------------------------------ ----------------------------------------- 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
------------------------------------------ ----------------------------------------- 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
Hang on a second. If absorption is 1.1g/g in espresso, and the retained liquid is 3.64% TDS, then that's 0.6g of extracted solids unaccounted for. That's the difference between 19.6% extraction and 23.6% extraction! Am I wrong?
I think GlennV is correct. For the purposes of a percolation brew, it isn't extracted if it's still in the puck. The composition of solubles there is different than what is in the cup, so the traditional yield method of calculating extraction makes sense. In immersion brewing, where the solubles in the puck are virtually identical to what is in the cup, what's in the puck IS "extracted".
This is why it is reasonable to pretend that the retained liquid in a drip brew has solute concentration of zero.
I think GlennV is correct. For the purposes of a percolation brew, it isn't extracted if it's still in the puck. The composition of solubles there is different than what is in the cup, so the traditional yield method of calculating extraction makes sense. In immersion brewing, where the solubles in the puck are virtually identical to what is in the cup, what's in the puck IS "extracted".
This is why it is reasonable to pretend that the retained liquid in a drip brew has solute concentration of zero.
For most percolation methods - it doesn't matter. I propose that espresso is slightly different.
I tried (but failed) to do this experiment, then just ran out of time, but consider this:
Imagine stopping collection of a shot of espresso at 17% extraction, then catch the next percent. Is that extra percent relevant to the cup?
Now do it again, but stop at 15%, then catch 15% to 20% extraction.
Or, stop at 18.5% extraction and catch the stuff from 18.5% to 21%.
The only difference between these segments is where we decided to end the extraction.
Just because we didn't include it in the cup doesn't mean it isn't coffee - it isn't coffee based on "standard" definition, and technically it isn't "extracted". However - consider that it was dissolved and transported - it just happens that for most drip/percolation methods, the amount stuck behind is too small and there hasn't been a way to asses its strength until recently for it to matter. And for the most part, it's true and Lockhart's thoughts on the subject work - except there is a clear preference for modern espresso with increasing strength (ristretto and such) to be extracted to only 19% or even slightly less, per "standard" definition.
For most percolation methods, the coffee in the grounds is abyssmally weak, and is a significantly lower percentage of the total coffee so that it is appropriately irrelevant. For espresso, however, the strength of the stuff coming out of a normal pull after the barista says "done" is pretty strong - stronger than even strong brew coffee. It's definitely part of the taste - but not the FULL taste - and it does contain bitter notes that aren't really present in the cup.
In fact, the percentage mass of the coffee stuck in the grounds is fairly small (2/17 or so) and 1/3 the strength. But if you were to think of all of the wet stuff including any coffee in process of dissolution as "coffee" - for an espresso pull this liquid in the puck might be 1/3 of the total mass of coffee "in process" and produced coffee combined. Even at 1/6 of the strength (my estimation) it still could be considered coffee.
------------------------------------------ ----------------------------------------- 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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