Posted Wed Oct 3, 2012, 5:39am Subject: Re: Drip/ pour over coffee to water ratio
jpender Said:
Which ballpark? Some of them have pretty deep center fields.
"...to this day I have never purchased a delicious 1-cup pourover or Chemex brew in a cafe. The reason is that manual drip is extremely challenging to make well." - Scott Rao, Everything but Espresso
I didn't say Rao was right. It is challenging, though. I feel sorry for him - this has not been my experience.
At a Starbucks? I'm completely in agreement with Rao. Not unless I go behind the counter and do it myself. They have ZERO clue on how to do a pourover - it's a dump and drain (a CCD with zero steep and 170°F water if you're lucky). However, a conscientious cafe can do a really good chemex/pourover with fairly low effort - and they have the advantage (again, if conscientious) of doing them day in and day out.
He is absolutely right on challenging nature of single cup brewing. Just look at a quick error analysis on water and coffee mass:
Target Brew: 450g brew water 25g brew coffee (18 Brew Ratio) Assume your brew method is 2.0 Absorption.
If everything is spot on, and done at 20% extraction: 450g + 25g -> 75g wet grounds + 400g coffee. 5g TDS in the cup, for a strength of 1.25%
Miss the ground coffee by 1.5g (measure it before you grind, and assume your grinder retains 1.5g) 450g brew water 23.5g brew coffee 18.75 water brew ratio
450g + 23.5g -> 70.5g wet grounds + 403g produced coffee. 4.7g TDS in the cup, for a strength of 1.17%. Just an error of 1.5g means going from target strength to near the low end of target strength.
Conversely - if you assume you had exactly 25g brew coffee and 450g brew water, your error in extraction is:
Strength 1.17%, 403g produced coffee, backcalculated TDS = 4.71g, but you made the assumption you had 25g of coffee you'd think you achieved only 18.8% extraction (but actually achieved 20%).
Everyone thinks they're better than this, but then someone talks in "scoops" of coffee. My AeroPress scoop ranges from 11.4g to over 14g (depending on the coffee) - if absolutely level. Add or subtract 1 bean from that scoop and the mass changes by about 0.1-0.15g.
Worse yet - measuring the brew water in "cups" or "fluid oz" of water, or even ml - measured with a pyrex cup or just the little lines on the brewer reservoir. Lucky enough if you get within maybe 10 ml in 450, but the volume error from measuring cup to measuring cup is maybe +/-2.5% on the generous side - in the range of half liter/half kilogram measurements. This is in the range of single cup brewing - and it doesn't take much sloppiness to have significant error.
------------------------------------------ ----------------------------------------- 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
If you have the mass of the brew water (W), mass of the brew coffee (C), and you brew it, you end up with mass of the grounds (G) and mass of the produced coffee beverage (P).
The relationship of what the mass of the spent grounds is depends on absorption (A).
P = W - (A * C)
in your case
400g = 450g - (2 * 25g)
The mass of the grounds (G) is equal to C * (A + 1),
so the OTHER equation that describes brewing is:
W + C = P + G, or, W + C = P + (C * (A + 1))
or in your case:
450g + 25g = 400g + (25 * (2 + 1))
You could define R = (W/C) and substitute, and then develop the set of scaleable formulas that makes up the brew chart.
------------------------------------------ ----------------------------------------- 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
In your experience, does coffee that is stronger/weaker suffer in taste as much as coffee that is a over/under-extracted?
Of course sloppy measuring isn't the only reason why single cup pourovers can be challenging. Do you find it "easy" to get consistent and even extractions with this method?
No, "extraction" seems to be the dominant taste factor (for me), and more primarily overextraction. Technical underextraction (back-calculated extractions of 17% or so) is actually harder to achieve than it seems, if you're using normal temperature brew water but more gently go into unacceptable taste. Stated another way - it's safer to underextract than overextract, you're more likely to have something drinkable.
Changes between 1.15% and 1.25% strength are detectable - but remember we want the highest accuracy for "extraction", so making a mistake in strength means errors in calculated extraction.
jpender Said:
...Of course sloppy measuring isn't the only reason why single cup pourovers can be challenging. Do you find it "easy" to get consistent and even extractions with this method?
Of the manual methods, I find pourovers fairly consistent, but less consistent than steep methods. I think it's easier than setting up a vac brewer. Or a Moka pot. :^p
Of course, your mileage may vary.
I have the choice of popping out the CCD valve plate and using it like a pourover. I can get really consistent results with it as a pourover, but it's a bit fussier than updosing a bit and using it as a steep/drain brewer. You have to try and time the delivery rate around the percolation rate after initial bloom. Easier to dump, stir, and drain when the grounds drop.
------------------------------------------ ----------------------------------------- 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
In oz {[64oz water - (4oz coffee x 1.5oz water/4oz coffee)] x .0013}/4oz coffee ~ 19% extraction In grams {[1814g water - (113g coffee x 42.5g water/113g coffee)] x .0013} /113g coffee ~ 19% extraction
Water - (coffee x Absorption/coffee) x TDS /coffee = Extraction %
Posted Wed Oct 3, 2012, 2:44pm Subject: Re: Drip/ pour over coffee to water ratio
Burner0000 Said:
Ok. My next question, is there a way to calc strength (TDS) without a meter?
W-Water 450g C-Coffee 25g A-Absorption Cx(2+1)=A 75g Correction, A = 2.0 P-Coffee brewed in the pot 400g
(W)450g+9(C)25g=475g-(A)75g=400g(P)
so this equation becomes 450 + 25 = 400 + 75 and 400 = 450 - (2 * 25) Notice the second equation only has the produced coffee and has no place in the equation for the grounds mass.
Here is the equasion below: It's at the bottom of the SCAA chart page
In oz {[64oz water - (4oz coffee x 1.5oz water/4oz coffee)] x .0013}/4oz coffee ~ 19% extraction In grams {[1814g water - (113g coffee x 42.5g water/113g coffee)] x .0013} /113g coffee ~ 19% extraction
Water - (coffee x Absorption/coffee) x TDS /coffee = Extraction %
In a nutshell - there is no way to calculate strength without a meter or a method of measuring it. Notice where it says "...measure the strength to be 1300ppm..."
The only way to know strength is to measure it. The only way to know extraction is to extrapolate it from a measurement of strength.
In the "070516_SCAE_Gold_Cup_Filter_Presentations.pdf" found out on the internet, page 77:
Tools to measure brew strength: Refractometer Oven Dehydration Hydrometer Drying Method Total Dissolved Solids (TDS) Meter
The author mentions oven dehydration and drying method - but only has one page describing the same thing. The author also includes brewing control chart - but you can't use it to measure, all you can do is use it to set a recipe that has a chance of brewing within the SCAA "gold cup" standards - but it can in no way be used to measure strength. Given a measurement of strength, you CAN use the brewing control chart to chart extraction (or you can calculate it) based on your measurement of strength.
------------------------------------------ ----------------------------------------- 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 Wed Oct 3, 2012, 2:49pm Subject: Re: Drip/ pour over coffee to water ratio
Think of it this way:
Use the brew chart to choose a recipe that targets a desired result (strength and extraction). This sets the ratio of brew water to brew coffee.
Brew the coffee using that recipe.
Measure the strength of the produced coffee.
Use the strength to calculate extraction.
You can't guess or know for sure what the strength is, and it is even more difficult the stronger your coffee is brewed.
Given two strengths, most people need them to be about 20% different before they can detect a difference. That is surprisingly large.
This means you may or may not be able to tell the difference between 1.25% and 1.15% strength, and you'll probably be able to tell the difference between 1.00% and 1.25%.
Double or triple the strength, or work in espresso strengths, and people will just barely be able to tell the difference between 5.5% and 4.7%, assuming they are extracted to the same amount.
------------------------------------------ ----------------------------------------- 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
That's what I thought. It's what my more limited experience is as well. I happen to prefer coffee that is stronger than the so-called American standard of 1.25%. But when I brew it to attempt to achieve that standard strength it doesn't taste better to me, just weaker.
So that would suggest that the challenge of single cup pourovers isn't primarily about measuring coffee and water carefully enough to hit the target strength. It's about the difficulty in evenly extracting the grounds. The water temperature and flow rate can vary considerably depending on just how you pour.
Netphilosopher Said:
Of the manual methods, I find pourovers fairly consistent, but less consistent than steep methods. I think it's easier than setting up a vac brewer. Or a Moka pot. :^p
I've had mixed results with single cup pourovers myself. Easier than a moka pot! I like that.
I've never made cheesecake but I know enough about baking, or cooking in general, to never say that it's easy. It isn't. There are subtleties that aren't communicated with a written recipe.
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