jlt3b Senior Member Joined: 24 Jan 2009 Posts: 62 Location: Philadelphia, USA Expertise: I like coffee
Espresso: Mini Vivaldi II, old... Grinder: Baratza Vario Drip: Hario V60, Clever Coffee...
Posted Mon Sep 17, 2012, 7:28pm Subject: coffee extraction as it relates to photography exposure?
Hi everyone, This is a general coffee extraction (over or underextraction) question that requires some understanding of photography to understand.
In photography, if all other variables are held constant, one can make discrete changes in the aperture of the lens and then make changes in the shutter speed of the camera of equal but opposite magnitude (eg, increasing 2 stops with the aperture, and decreasing 2 stops with the shutter speed). The resulting overall light exposure will be the same, but the picture will look very different. (note - I do realize there are several other variables, including the brew temperature, etc).
My questions pertain to coffee extraction. Specifically, with many pour overs and with the clever coffee dripper, I often tend to taste a sour note in the brew, regardless of the beans that I use. I believe this happens when I underextract. I know that the extraction can be increased by several factors, two of which include grinding the beans more finely, and/or increasing the brew/dwell time.
Here are my questions: 1) Will the resulting cup of coffee taste dramatically different if I preferentially change one of these variables only, in an effort to acheive greater extraction (and hence a less sour cup).
2)Is one of these options 'better' at obtaining a rich, non-sour, full bodied cup of coffee?
Posted Tue Sep 18, 2012, 7:25am Subject: Re: coffee extraction as it relates to photography exposure?
jlt3b Said:
Hi everyone, This is a general coffee extraction (over or underextraction) question that requires some understanding of photography to understand.
In photography, if all other variables are held constant, one can make discrete changes in the aperture of the lens and then make changes in the shutter speed of the camera of equal but opposite magnitude (eg, increasing 2 stops with the aperture, and decreasing 2 stops with the shutter speed). The resulting overall light exposure will be the same, but the picture will look very different. (note - I do realize there are several other variables, including the brew temperature, etc).
My questions pertain to coffee extraction. Specifically, with many pour overs and with the clever coffee dripper, I often tend to taste a sour note in the brew, regardless of the beans that I use. I believe this happens when I underextract. I know that the extraction can be increased by several factors, two of which include grinding the beans more finely, and/or increasing the brew/dwell time.
Here are my questions: 1) Will the resulting cup of coffee taste dramatically different if I preferentially change one of these variables only, in an effort to acheive greater extraction (and hence a less sour cup).
2)Is one of these options 'better' at obtaining a rich, non-sour, full bodied cup of coffee?
Weird - are you reading my notes? I thought that access to my notes on my home computer are fairly well-protected... LOL
I was scribbling something similar about film photography and coffee, but the analogy is slightly different.
I liken roasting to capturing the exposure: the photographer chooses the equipment (camera, lens, film), the subject, composes the shot with lighting, chooses the settings and takes the picture (exposes it to the film). At that point, you know you have a picture, you think it's decent. BUT, you don't really know until...
...you develop it.
When you roast coffee, you control all the variables (choosing the varietal, or blend if you choose, the roasting profile, method, how dark, how long to rest, how to store while resting). You think you've got a great coffee, but you really don't know until...
...you brew it.
So then brewing is like developing an exposure and making a print. (BTW - did you know you can develop B&W film with coffee and ascorbic acid?)
With photography, during developing you can change some of the variables - you can develop it as color and convert to B&W (color development is a PAIN), change the size of the final print after the negatives are developed, change the appearance by altering the developer bath time, wash the print to make it sepia.
But, you cannot change WHAT the PICTURE IS. You can mess it up, but the window for getting something that looks acceptable is not wide open - there is an optimum range for the development process. Changing how you develop the film will not change a picture of a mountain into a picture of a skyscraper.
Like brewing coffee, you cannot change what was set by roasting. You can mess up excellent coffee by brewing it wrong, and the range for acceptable brewing is not wide open. You cannot magically make malty notes appear if the varietal you chose did not have them, nor are you likely to have really bright acidity in a coffee that is roasted well into vienna. You pick the brew method, the brew ratio, the grind level, and follow the brewing recipe.
I just thought it was interesting how so many of our thoughts follow similar lines of thinking.
Regarding "extraction", think of this as the developer stage of photography (bear with me, it's been decades since I processed film). Timing is everything - development time changes the grain size and darkness of the overall picture, and has dramatic effects on contrast and the look of saturation. Even how much you agitate during development can change the development of the picture. Once you have the negative, all of these can be again changed during printing (where you enlarge and expose to print and develop THAT print).
Sour is a typical hallmark of HOT underextraction. There's a difference between hot underextraction (typically too short dissolution time) and cooler underextraction. I've found that increasing the extraction if you have been finding consistent sour notes may help (by developing the rest of the coffee) BUT the sour notes will still be there. IF the sourness is actually due to underextraction.
Is it possible that "sour" is more "bitter" for you? I had one friend describing "sour" coffee, only to find out that his brewer was achieving about 23% extraction on a weaker brew ratio. What he thought was "sour" was actually OVERextracted. It is possible that you're experiencing a tinge of overextracted bitter compounds that can be quickly dissolved in the invariable "dust" particles of the grind. A better grinder can help, if that's the issue, but probably reducing your strike temperature would be more effective. (just dropping to 195°F from 205°F can make a huge difference)
regarding your questions:
1) yes. 2) it depends.
What is it that makes you think you're underextracting? You sound fairly thorough and experienced, so you're probably fairly conscientious about water temps and such. What "recipes" do you use?
------------------------------------------ ----------------------------------------- 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 Tue Sep 18, 2012, 7:28am Subject: Re: coffee extraction as it relates to photography exposure?
Sorry. Accidentally reposted.
------------------------------------------ ----------------------------------------- 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
jlt3b Senior Member Joined: 24 Jan 2009 Posts: 62 Location: Philadelphia, USA Expertise: I like coffee
Espresso: Mini Vivaldi II, old... Grinder: Baratza Vario Drip: Hario V60, Clever Coffee...
Posted Sat Sep 29, 2012, 7:19pm Subject: Re: coffee extraction as it relates to photography exposure?
Hi Netphilosopher ,
Thanks so much for your fun and thoughtful reply. I'm sorry that I am so late in reciprocating the courtesy - work had me running ragged.
I enjoyed reading your post, and got many-a-chuckle from it... Most importantly, however, it helped me greatly because I do believe that some of my 'sour' flavor was due to my brewing at temperatures that were a bit too high... When using my clever coffee dripper and grinding with my Baratza Vario, I was using water that was a minute or less 'off the boil'. I've been lowering my water kettle temperature (now at 205 degrees), and have definitely noticed less sour notes. So thank you very much!
Posted Mon Oct 1, 2012, 7:56am Subject: Re: coffee extraction as it relates to photography exposure?
It is weird - playing with my own CCD, I've been varying grind and contact time as well as strike temperature. Keeping the same brew ratio, I've noticed something curious: it seems that a clue to just about the right time to draindown is when the floating grounds submerge. On a coarse grind (French Press setting on my Bodum) this may be around 3 1/2 minutes, where on a fairly fine grind this may happen at about 1 minute or so.
Pour the water in all the way (I use 425g of water) and stir vigorously. Some grounds will float on top - you can see the particles poking through the foam and they are apparent when you stir it. In time, the grounds will begin to become waterlogged and sink into the brew slurry - leaving only the brown foam. It seems this is the time to put the CCD on the cup for draindown.
On French Press grind, draindown for 27g of coffee may take over 3 minutes, while on fine grind this might be only 40 seconds or so. Pretty consistently, this seems to be where I get strengths between 1.2 and 1.3%.
However, hotter strike temperatures have a small effect on when the submerging happens (shifts the time by 15 seconds or so - longer at cooler strike temps). But just off boil is where I get the harshest taste, even at 1.25% strength, and slightly worse taste on COARSER grind and hot temps (which is puzzling to me).
I tend to like the flavors with a strike temp around 195°F and a fairly fine grind with a shorter contact time (where the grounds drop in about 1 1/2 minutes). Just some interesting observations.
I first noticed grounds dropping in my AeroPress experiment and doing Mason Jar brews (warm and cold brewing).
------------------------------------------ ----------------------------------------- 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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