Posted Sun Sep 21, 2008, 6:42am Subject: Re: Recapping the Summer by Mark Prince
MarkPrince Said:
Andy, this ain't drip coffee. It's a different brewing method, and in fact, is more akin to the Clover than to a drip coffee maker.
Remember, the SCAA has no set standard (yet) for press pot coffee or full immersion brewed coffee. Their only published standard (which, IMO, I think should be evolved) is for flow through drip, AFAIK.
First of all, I was informed rather passionately by a coffee friend that my "SCAA standards" statement was a misnomer. The friend said that SCAA has merely passed on standards that were laboriously created by various other groups over many years (Norwegian Coffee Center, Specialty Coffee Assoc. of Europe, Midwest Research Institute, Coffee Brewing Center, George Howell Coffee Co, etc).
In any case, although you have a lot more experience in non-espresso brewing methods than I do, I am skeptical of your claim that Clover, drip, vacpot, Aero, French press, gym sock and other non-espresso methods each require their own standard. Of course they require somewhat different techniques for optimizing results, but I believe they all share a common process: achieving a balanced brew by extracting 18-20% of the ground coffee into an appropriately diluted cup using pressures under 0.5 bar.
Espresso, on the other hand, is a different animal, using much higher pressures and a very "UN-full immersion process" to produce a totally distinct beverage.
Having said these things, I would speculate that your preference for highly overdosed, highly underextracted Clover and Aeropress cups is analogous to many people's preference for highly overdosed, highly underextracted espresso ristrettos.
In matters like these, there are no "right" answers, only personal preferences. But again, I would say it's very likely a mistake for young coffee whippersnappers like you and me to throw out all the classic coffee research in favor of our own taste of the moment.
Why not continue brewing for a decade or two and see if you still have a taste for the coffee styles you are drinking now? I would bet that your tastes will change over time, probably more in line with the aforementioned coffee standards.
Posted Tue Sep 23, 2008, 4:39am Subject: Re: Recapping the Summer by Mark Prince
andys Said:
Having said these things, I would speculate that your preference for highly overdosed, highly underextracted Clover and Aeropress cups is analogous to many people's preference for highly overdosed, highly underextracted espresso ristrettos.
I could be mistaken, but my memory of conversations in the Aero thread suggests that Mark was early a critic of the underextraction that Alan Adler's methods with the Aeropress encourage. Others, like myself, never courted that end of the extraction spectrum with the Aero, preferring a full extraction.
I infer from Mark's remarks that he's dialed in that fuller extraction pretty well.
The Aero itself is capable of any extraction degree one prefers, and identical results can be achieved by varying means. Personally, using polyester felt, I prefer to go much finer with the grind, than to go coarse and increase the wet time. But that's possibly because most of my Aeropressings are a break from work, and I fear that a longer extraction duration might allow my inbox to grow beyond reason in the interim. ;-)
I have measured extraction of many AeroPress shots.
In the beginning, before I learned the art of pressing gently, I measured about 16%. But even a year after the AeroPress entered the market I was still learning to press more gently. Gentle pressing allows a finer grind and higher extraction.
I now routinely get 20% extraction with 175F water and about 30 seconds press time. And with an even finer grind and longer press time I've gone as high as 26% extraction with 175F water.
Interestingly, I did not taste any harshening of the flavor at 26% extraction. I believe that was due to the 175F water and the relatively short wet time.
I have measured extraction of many AeroPress shots.
In the beginning, before I learned the art of pressing gently, I measured about 16%. But even a year after the AeroPress entered the market I was still learning to press more gently. Gentle pressing allows a finer grind and higher extraction.
I now routinely get 20% extraction with 175F water and about 30 seconds press time. And with an even finer grind and longer press time I've gone as high as 26% extraction with 175F water.
Hi Scott, hi Alan, thanks for the interesting replies.
Question for both of you: exactly how did you measure extraction percent? It appears there are several methods. My measurements are made by first drying a ground coffee sample to determine the moisture-free mass. Then I prepare an espresso or aeropress coffee, dry the spent grounds, and see how much mass has been lost.
That is the method used in my report posted earlier this year. One conclusion then was that the Aeropress at a dose of 6.5 grams dry coffee and a 6% brewing ratio (dry coffee/water) could easily extract 20% solids. I'm just wondering how much solids Mark is extracting when the dose is 16-18 grams at an 8-9% brew ratio.
I began by weighing dried coffee grounds before and after brewing. But after I discovered that Brix is an excellent way to measure TDS, I switched to using Brix with this formula:
Extraction percent = 0.85 x Brix x (input water wt) / (input coffee weight)
It's based on the fact that percent TDS = 0.85 x Brix, as determined by Randy Pope -- chemist at Bunn.
Posted Tue Sep 23, 2008, 9:48pm Subject: Re: Recapping the Summer by Mark Prince
andys Said:
Question for both of you: exactly how did you measure extraction percent? ... One conclusion then was that the Aeropress at a dose of 6.5 grams dry coffee and a 6% brewing ratio (dry coffee/water) could easily extract 20% solids. I'm just wondering how much solids Mark is extracting when the dose is 16-18 grams at an 8-9% brew ratio.
Ah, hadn't seen that write-up. Nice. I'm not sure about Mark's scenario.
BTW, I've also concluded that a whirly is "just fine, thank you" for Aeropressing -- at least, with poly (which allows great throughput with a much finer grind). I can't prove it with my budget, but I'm pretty sure that a whirly grinds far more consistently when the grind in it is taken quite fine, thus allowing for a consistent extraction. The key, then, is terminating it on time, and quickly. High-throughput filtration allows the latter, and sheer genius ensures the former. ;-)
We use a burr grinder at the market, but every day at work I use a whirly. At home I only do espresso any more, but that's rare simply because I'm so rarely home. :-/
I'll defer to Alan on real measurements; my only judgment is subjective based on cupping (which, with my palate, is a doubtful undertaking but it's all I have to work with just now). Jim Schulman was doing some mad extraction measurements a couple years ago, as I recall -- splitting pucks and stuff (espresso, not Aero). Weren't you in on that? Excellent methods, IMO.
I began by weighing dried coffee grounds before and after brewing. But after I discovered that Brix is an excellent way to measure TDS, I switched to using Brix with this formula:
Extraction percent = 0.85 x Brix x (input water wt) / (input coffee weight)
It's based on the fact that percent TDS = 0.85 x Brix, as determined by Randy Pope -- chemist at Bunn.
Yup, I'm familiar with the formula, and lately I've been experimenting to see how well it correlates with the results of the drying technique (for aeropress coffee, and for espresso, too). But, it seems to me, the formula should be a little different than what you posted:
Extraction percent = 0.85 x Brix x (beverage wt) / (input coffee weight)
nickcho Senior Member Joined: 7 Nov 2002 Posts: 435 Location: Redwood City, CA Expertise: Pro Barista
Espresso: this Grinder: that Vac Pot: yes Drip: drop Roaster: Trish!
Posted Wed Sep 24, 2008, 5:45am Subject: Re: Recapping the Summer by Mark Prince
andys Said:
First of all, I was informed rather passionately by a coffee friend that my "SCAA standards" statement was a misnomer. The friend said that SCAA has merely passed on standards that were laboriously created by various other groups over many years (Norwegian Coffee Center, Specialty Coffee Assoc. of Europe, Midwest Research Institute, Coffee Brewing Center, George Howell Coffee Co, etc).
Just an FYI, I asked a "coffee friend" about this myself, and here was his response:
The current SCAA standards are the culmination of the work of a wide variety of groups, including the Norwegian Coffee Center. The bulk of the material and testing used to develop the standards came from the Coffee Development Group, an organization funded by the ICO, that disbanded after the collapse of the ICA, and closed all international offices of the CDG in late 1990. Many individuals, including Ted Lingle (former SCAA Exec. Director) contributed to the development and publication of those standards. Additional work has taken place over the years, most recently as set of experiments designed to determine if new parameters of extraction needed to be set for dark roasts. You should also know that the SCAA owns the US rights to all of the research and publications of the CDG.
Finally, one of the principal differences in the SCAA and NCC standards is a slightly weaker cup for the SCAA. This reflects consumer preference in the US as measured in impaneled consumer tastings. It may indeed be time to revisit these tastings, although I suspect that they will yield the same results today. In any event, the science is the science. No one owns it, and all can repeat it. As a side note, the SCAE didn't exist until long after the SCAA published and promoted these standards.
My curiosity was (understandably) piqued... and I wanted a more informed source for this. :-P
Yup, I'm familiar with the formula, and lately I've been experimenting to see how well it correlates with the results of the drying technique (for aeropress coffee, and for espresso, too). But, it seems to me, the formula should be a little different than what you posted:
Extraction percent = 0.85 x Brix x (beverage wt) / (input coffee weight)
Your formula fails to account for the brew trapped in the used grounds. For AeroPress, that amounts to about 1x to 1.2x the weight of dry grounds. For drip it's about 2x.
My formula assumes that the brew strength of the liquid trapped in the used grounds is about the same as the part you drink. I've verified that to be correct.
Posted Wed Sep 24, 2008, 7:02pm Subject: Re: Recapping the Summer by Mark Prince
nickcho Said:
Additional work has taken place over the years, most recently as set of experiments designed to determine if new parameters of extraction needed to be set for dark roasts.
Hi Nick, thanks for the info. Actually, I have no expertise to agree or disagree with what your "coffee friend" said vs what my "coffee friend" said. If there's a tussle, I guess the intellectual property attorneys will sort it all out in the end....
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