I wrote "So, my current thinking is that high extraction is not detrimental to flavor if the brewing temperature and time are not excessive." (empahsis added)
In my experiments, the only variable was fineness of grind. I never steeped beyond the standard ten-second stir, and press time never exceeded one minute. I think the increased extraction with the finer grinds was due to their presenting more exposed surface area to the water. The stress on the ground coffee was relatively constant, except for a slight increase in press time as the grinds got finer.
Posted Mon Aug 20, 2012, 5:05am Subject: Re: Aerobie Aeropress
andys Said:
Obviously you are entitled to your opinion. But your statement is in conflict with 60 years of blind testing, the guidelines of all the national specialty coffee associations, the double blind testing recently performed by David Walsh, and dozens (if not hundreds) of contemporary coffee professionals.
You don't disclose the details of your methodology, so it is hard to evaluate your claim. But your observations lack credibility for several reasons: The equipment that you previously described using for measuring TDS doesn't possess the accuracy or resolution to measure coffee properly. Are doing the math right? Who knows? The Aeropress is a terrific invention for which you deserve abundant credit, but it is not magic and does not reinvent the physics of brewing.
This afternoon I tried making a batch to test out your assertion:
Aeropress, inverted technique, standard paper filter George Howell coffee blend, ground espresso fine 13.1g dose, 222g brew water at 175F Steeped a long time, with gentle occasional stirring Pressed very gently (this took two full minutes) TDS measured at 1.45% using a VST Lab refractometer Extraction yield calculated out to 24.9% using Extractmojo v3.0 in immersion mode
This was not a blind test by any means, but the brew had a distinctly bitter cast that got stronger the longer it sat in my mouth. It was not sweet at all.
I think 9 out of 10 coffee drinkers would decline to drink that test coffee batch if also given a choice of a coffee at similar strength brewed to 20% extraction yield.
I think it would be a terrible shame for coffee aficionados to buy high quality specialty coffee at $20/lb and ruin it by taking your advice. On the other hand, people who don't mind gas station coffee might be fine with it.
I do blind tests all the time - not on me, but I serve unknown coffee to my wife for an unbiased opinion. IMHO, her palate is very good - and she picks up on subtle things that I sometimes miss due to confirmation bias.
In above example, R = 16.95 SR/(1-S) = (16.95*.0145)/(1-.0145) = 24.9%
If I serve 24.9% extracted coffee to her, she'll likely spit it out. She is quite sensitive to bitterness and astringency. I've done this blind, time and again, even adjusting and diluting to serve at 1.15-1.25% strength. Bitter notes start to come in anytime the immersion extraction creeps up much above 21.5%.
Espresso fine grind, Andy, will achieve overextraction, (>22.5%, or a strength >1.30% with R=17) even with lower temperature water, pretty quickly - about 45 seconds to 1 minute. The fact that Alan is terminating the brew after 10 second steep means he's still climbing the extraction curve - even during the press. The last few tests I've done I'd estimate that the strength of the coffee is probably around 60%-75% of the final strength after long steep time within about 30seconds, and approaching 90% within 2 minutes. Finer grind is quicker AND higher strength, lower temperature stretches the time scale.
I've done fine grind at 10 second steep in AP with 175°F water - and I've gotten extractions right around 19%-20% (Strength about 1.25% with R = 15, W=255 C=17, Cp ~230g), so I don't doubt that a fairly decent extraction is possible. My issue is that the 10 second steep is really short, and therefore I'm pressing at the steepest part of the extraction curve. Additionally, that 10 seconds alone on fresh coffee is really REALLY sensitive to bloom. I find that just 10 to 20 seconds is a huge change in taste and strength, and can easily tip toward overextracted in a few heartbeats.
Not saying right or wrong, just saying that taste is subjective. My personal opinion is that other than subtle adjustments, Lockhart's extraction ranges are still a great guideline for me (and my wife! :D ). I've seen good coffee brewed badly that people LOVE, and bad coffee well-brewed that people LOVE, but I've never seen bad coffee badly brewed that people love.
Good coffee can be a buffer to "normal" taste, and even badly or oddly brewed can yield something significantly better than Folgers brewed with a 22 Water Brew Ratio that's sat in the office swill pot brewing up caffeoylquinnic acid for an hour...
------------------------------------------ ----------------------------------------- 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
Posted Mon Aug 20, 2012, 5:10am Subject: Re: Aerobie Aeropress
Additional comment:
By variable, I mean 10 second steep on same coffee same grind may have a large variation in end strength. I rarely overextract with 10 second steep - the grind has to be very fine for that to happen (almost turkish).
Just the difference in bloom for 3day post roast and 8 day post roast can change the end strength from 1.25% to 1.38%. IMO, 10 seconds is just too short to be consistent with a manual steeped 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
Posted Fri Aug 24, 2012, 11:43am Subject: Re: Aerobie Aeropress
jbviau Said:
Oh, well if upgrades are on the table, how about adding a little Trifecta-style check valve on the bottom to eliminate premature drip-through and render the inverted method obsolete? ;)
To the extent that inverted brewing in the Aeropress = nothing more than that, sure. But I'm not convinced you're right; there's that pesky "press" factor, for example.
AlanAdler Said:
As I've often written, normal drip-through does not make a difference in the strength or flavor of the brew. I invite you to try two pressings:
Informally, I agree drip-through doesn't cause taste problems IF you're brewing with a paper filter AND either grinding finely with a quick steep OR using the plunger (insert, then pull back slightly) to keep drippage in check. However, not everyone Aeropresses this way. For instance, metal filters are popular. About those, even with the Able DISK Fine (which is pretty fine-gauge) I get more drip-through than I'd like (yes, tastewise) unless I invert or grind more finely than usual.
Which brings me to a "grind issue." Maybe I'm revealing my ignorance here, but I don't think anyone is going to argue that using a coarser grind and steeping longer in the Aeropress is 100% equivalent in terms of cup quality to what you get when you go with a finer grind and shorter steep time. The former is a gentler extraction that some might prefer--hence (I assume) the appeal of the inverted method. At least that's why *I* like it.
Anyway, it's in this spirit that I half-jokingly proposed adding a check valve. Thanks for your participation in this thread!
Posted Fri Aug 24, 2012, 2:19pm Subject: Re: Aerobie Aeropress
Hi,
Long-time lurker, first-time poster. I've recently switched from brewing with a press pot to the aeropress, partly because I brew at work and love the ease of cleanup, and partly because I'm intrigued by how easily you can manipulate the process/variables. I'm finding this thread a bit difficult to navigate (I made it through around 30 pages and had to stop), so I apologize if the following questions have been hashed out elsewhere in the thread.
I've been messing with as many variables as I can, and thus far I've settled on this brew method as my favorite:
Invert method, paper filter (not sure I even need to invert with paper judging from these posts?) 15g of coffee @ 15 declicks on a modded HMMS 100g brew water @ 205 F 30 second pour, stir, wait 30 seconds, press for 25 seconds (aiming for 1:30 total contact time) Dilute with 100g hot water
I started with a finer grind and shorter steep, but I found that the above method for me seemed to highlight the varietal characteristics of the cup a bit more, which is what I'm looking to get out of the thing (specifically the berry notes of a DP Sidamo, because it's my favorite flavor in coffee).
Now, I'm a complete amateur at this, but shouldn't I be able to get a similar flavor profile with a finer grind, by altering some other variables? How come I'm losing the berry notes when I go to a finer grind and a shorter steep (e.g. 9 declicks, 45s brew + 25s press)? Even with the HMMS mods, I feel 15 declicks is giving me some inconsistent grind sizes, so I would imagine that if I could reproduce the extraction of my favored method using a finer grind, that I'd get a more consistent cup, right?
Also, if there's a different ratio/grind/steep combination I could be using to get even more varietal flavor out, I'd love to keep experimenting!
Posted Fri Aug 24, 2012, 2:27pm Subject: Re: Aerobie Aeropress
You sound unsure and seeking guidance, altough it's hard to tell for sure online--Have you tried it the way it says on the package? The inventor, (Alan Adler), went to great effort in blind taste testing trials to develop and refnine that method, and I personally have not found a better tasting recipe myself, (taste being subjective and all).
Posted Fri Aug 24, 2012, 3:45pm Subject: Re: Aerobie Aeropress
dagoat Said:
You sound unsure and seeking guidance, altough it's hard to tell for sure online--Have you tried it the way it says on the package? The inventor, (Alan Adler), went to great effort in blind taste testing trials to develop and refnine that method, and I personally have not found a better tasting recipe myself, (taste being subjective and all).
The guidance I'm specifically seeking is some insight into how grind size, steep time, and extraction interact. Obviously to maintain a certain extraction, grind size and steep time will have an inverse relationship, but I'm curious if anyone (looking at you Netphilosopher ;)) has looked at the constants/multipliers involved. For example, suppose I start with 14 declicks mod HMMS @ 1:30 contact time. Now suppose I tighten the grind to 7 declicks. If I want my extraction to remain the same, does my contact time also halve to 45 seconds? I think the answer is probably no, and I'm wondering what the curve looks like.
As for the default instructions, yes I've tried them, and I don't like them at all. I did the following experiment with the default instructions when I was playing around with different brew methods:
Brew three coffees (DP Harrar at Full City, DP Sidamo at Full City, Aged Sumatra at ?? - probably Full City+) using the instructions on the package (the instructions weren't precise, but I used 20g coffee @ 7 declicks on mod HMMS, 175 degree brew water to #2 circle, ~10s pour time, 10s steep/stir time, 25s press).
Label the bottom of three identical mugs, wait for them to cool, have friend serve them to me in random order.
I could pick out the Sumatra, but I could not tell the difference between the Harrar and Sidamo. The coffee was clean but very uninteresting - if you'd asked me to guess totally blind, I'd have labeled the African DPs as Costa Rican or a Columbian WPs. Ouch.
I repeated the experiment with the process I used above, and I could easily pick out the three varietals. The Harrar let out some hints of lemon and berry, and the Sidamo had huge berry and melon. The finish of the Sidamo and Harrar were also quite different - lingering berry (maybe strawberry?) in the Sidamo and a much stronger chocolate for the Harrar.
I'm satisfied with the method I use now, but, e.g., a few months back I had a pourover of a Rwandan coffee at Intelligentsia that blew me away - it almost tasted as if lemon herbal tea had been mixed with the coffee. I would love to be able to get that much of the "non-coffee" flavors out at home.
Posted Fri Aug 24, 2012, 6:22pm Subject: Re: Aerobie Aeropress
nroot Said:
The guidance I'm specifically seeking is some insight into how grind size, steep time, and extraction interact. Obviously to maintain a certain extraction, grind size and steep time will have an inverse relationship, but I'm curious if anyone (looking at you Netphilosopher ;)) has looked at the constants/multipliers involved.
Um... yeah, I may have dabbled with this on occasion. :D
nroot Said:
For example, suppose I start with 14 declicks mod HMMS @ 1:30 contact time. Now suppose I tighten the grind to 7 declicks. If I want my extraction to remain the same, does my contact time also halve to 45 seconds? I think the answer is probably no, and I'm wondering what the curve looks like.
So, here's what I'm finding out with my HMMS. It's a great portable burr grinder. It's a little fussy. Out of the box, it sux. I have trouble keeping the mods to stick - plastic, aluminum tape, etc. - they all wear out in either 1.5kg (plastic and tape) or by about 6kg of coffee (aluminum tape). What it needs are really good needle bearings, a stiffer center shaft, and a better control over the center burr.
I can get it as good as my Bodum Bistro Burr Grinder - but only for a couple of weeks, then it begins to generate excessive fines from the center burr eccentricity. These fines clog up a Melitta filter (I use in CCD) and also increase fines that make it through the first pressings into the cup. There doesn't seem to be anything I can do to improve this without re-designing the little thing. 15 declicks is great for about 2-3 minute steep for inverted AeroPress at first, but after wear the grind inconsistency comes on.
I'd guess that 7 declicks is getting pretty fine - not quite espresso, but definitely finer than drip. At least it is on mine.
In general, the extraction curve looks like a typical exponential curve. Starts out within a few seconds at about 50% of end strength, and if you let it sit, the end strength is where several minutes will not change the strength of the brew. Most grind levels will achieve this by 8 - 12 minutes.
-Brew ratio changes the STRENGTH of the curve, but extraction is roughly the same for different brew ratios. -Finer Grind level increases the speed of extraction, and also increases the equilibrium extraction. This does imply that there is potentially a grind level (about 1.5mm) that won't achieve overextraction (provided there are very few <200micron particles) in under 12 minutes. You need a really good grinder to make regular sized particles of this size. -Lower temperature stretches or scales the time portion, slowing the speed of the extraction, but generally not the equilibrium extraction.
There are secondary effects to temperature, based on my observations:
-Temperatures >205°F have a fair chance of bringing in bitter tones to the coffee. I suspect there is some sort of lipid bound with roasting compounds that requires high temperatures to extract. Some call this "scalding" the coffee or "overextracting" the coffee, but that's not technically true.
-Temperatures <205°F but >165°F have a good chance at acceptable extraction - provided the time is adjusted to achieve the desired extraction. 165°F on a very coarse grind may completely lose energy and underextract before achieving potential equilibrium.
-Temperatures approaching room temperatures (cold brewed) will take on significant tea-like overtones, and (IMHO) can lack large portions of the taste we think of as "coffee".
With very fine grind, you can achieve overextraction (i.e. more than the Lockhart recommendation) in under 3 minutes, and using a lower temperature can give you a chance to catch it before it goes over. For me, though, it can make the time from first pour and bloom to press a bit... rushed. Trying to do 10 second steep and press just doesn't work for me.
Experiment, too. You can do a "pourover" of sorts with the AP. You can even use the basket from an auto drip as a pourover device. And you can do immersion brews in a mason jar and use the AP as a filtration/extraction device.
'sall I got time for tonight. I have some more data to crunch...
------------------------------------------ ----------------------------------------- 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
Right, so this is where I'm at - I'm starting to get fines again. My thought is, take your recipie, for example, which actually looks pretty similar to what I'm doing. Now keeping the water temp and brew ratio constant, suppose you change the grind to 9 declicks. If you could alter the brew time to keep a 20% extraction, would you be getting a better cup because the fines are closer in size to the actual grind?
This is sort of what I'm looking for: the correct brew time at finer grinds. It makes sense that the shape of the time vs extraction curve is exponential, but what is the shape of the grind size vs brew-time-to-20%-extraction curve?
In my example I suppose the ideal graph would be #-of-declicks vs brew-time-to-20%-extraction, but even just a general idea of what a curve like that would look like would help narrow down the ranges in which I should experiment.
Posted Sat Aug 25, 2012, 9:08am Subject: Re: Aerobie Aeropress
nroot Said:
Right, so this is where I'm at - I'm starting to get fines again. My thought is, take your recipie, for example, which actually looks pretty similar to what I'm doing. Now keeping the water temp and brew ratio constant, suppose you change the grind to 9 declicks. If you could alter the brew time to keep a 20% extraction, would you be getting a better cup because the fines are closer in size to the actual grind?
This is sort of what I'm looking for: the correct brew time at finer grinds. It makes sense that the shape of the time vs extraction curve is exponential, but what is the shape of the grind size vs brew-time-to-20%-extraction curve?
In my example I suppose the ideal graph would be #-of-declicks vs brew-time-to-20%-extraction, but even just a general idea of what a curve like that would look like would help narrow down the ranges in which I should experiment.
Well, because of the inconsistency in grind, I'm not using my M-HMMS for experimentation. I've found that the Bodum Bistro is pretty darn consistent - same coffee same brew parameters same grind setting I get repeatable strength within +/-0.03% or so.
I figured that once I get this experiment set finished, I can then map something like a Ditting to my Bodum - reasoning that if the extraction curve for setting 7 on a Ditting matches my bodum at 5.5 from drip (Drip being zero), then I will have a good idea of "effective" grind size for M-HMMS to a semi-standard grinder like a Ditting by doing a few test brews.
and for a specific brew ratio (this is coffee brew ratio, in percentage, meaning 7.5% brew coffee:brew water) a series of AeroPress extractions terminated at several progressive times on same grind level (+4 on my nomenclature for the Bodum Bistro). Click Here (www.coffeegeek.com)
Yes, that's 7 different brews to make that one chart... it's not just a hobby - it's an obsession.
That's a rough idea of what the strength does (you can calculate effective extraction = SR/(1-S), where R=(1/.075)) for one given set of brew parameters. I originally thought that about 15 declicks on a fresh modification for the HMMS was roughly equal to this setting (D+4 on the Bodum). However, I'm not sure now - and probably have to re-map once I understand the full range of my grinder and time.
------------------------------------------ ----------------------------------------- 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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