jpender Senior Member Joined: 11 Jul 2011 Posts: 428 Location: California Expertise: I like coffee
Grinder: Kyocera CM-50 Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Thu Jun 14, 2012, 3:27pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
I meant extraction yield in the normal sense, the ratio of solubles in the cup to initial dry coffee. In my understanding the yield for an immersion brew goes down as brew ratio increases even if the strength goes up.
By "all else being equal" I meant user inputs. I didn't mean to imply that changing the brew ratio would affect only the yield and nothing else.
Netphilosopher Said:
BUT - even if you get two brews to work at same (ish) brew control parameters and same grind (i.e. you actually get a 6% brew ratio and a 12% brew ratio on a medium 550micron grind to work in 6 minute delivery time), the difference in percolation just from the depth alone, and the extraction that happens during the percolation, means that the higher brew ratio just won't extract as much as the lower brew ratio.
I'm not sure what your point is? The percolation rate is unintentionally affected but the yield still goes down.
Netphilosopher Said:
So, there's maximum extraction - which is valid for any bean any grind any brew method. You just keep brewing and measuring the produced coffee until there isn't any more produced coffee, and account for all that's extracted - there's no brew ratio, only the TDS that makes it to the cup.
If by "brewing and brewing" you mean more and more water, that's a brew ratio that is tending toward zero. If brew ratio and yield correlate negatively then the yield would tend toward a maximum in this case.
Posted Thu Jun 14, 2012, 7:23pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
jpender Said:
..
I'm not sure what your point is? The percolation rate is unintentionally affected but the yield still goes down.
If by "brewing and brewing" you mean more and more water, that's a brew ratio that is tending toward zero. If brew ratio and yield correlate negatively then the yield would tend toward a maximum in this case.
It's something I've been thinking about and turning over in my head (and attempting in practice). I figured I'd try and re-create the experiment with percolation method - but it's impossible to apply the same brew parameters to higher brew ratios in a pass-through gravity drip percolation method with same size filter like you can in immersion.
It does lead me to a different experiment:
We all know that "extraction" is based on contact time, grind size, and even though the brew charts don't show it, brew ratio (except for the new charts - by Bunn - they actually show an adjustment in the brew chart around the optimum brew range weirdly spread out). Of course temperature, but we'll keep that "in range" of 200°F-205°F.
Step 1) Work with a drip brewer you know well. Determine and know the contact time well for this brewer (the brew cycle time based on the amount of water you use - for example, my BCM-4C does 2g/second once it starts brewing). This will be your starting point for brew water, and will stay constant for step 1. Measure/check the temperature of the brew water - this will be duplicated for the next steps.
Use 8% brew ratio (reciprocal = 12.5), 8g coffee/100g of brew water.
Find a grind level that produces an end strength of 1.85% (which, if it works like most drip brewers, will have a yield extraction of 20%).
If you can, measure the strength of the last drippings coming out of the basket.
Step 2) & 3) Once you've done that, you'll use the same exact grind, contact time and brew ratio and water temperature to reproduce this with two other devices, recording the end strength.
-CCD
-AeroPress
Step 4) If you're really motivated, try and do a pourover of same brew ratio and grind in same contact period.
Don't forget to taste them - it's as close of a comparison of brew methods there is.
IF "extraction is extraction", then they SHOULD yield darn near the exact same strength, right? Same contact time, same grind, same brew ratio, same coffee, same brew chart. Yes, temperature drops in the immersion methods - that's why I added the pourover. It's subject to the same temperature drop as CCD and AeroPress. Great comparison of a percolation method to drip but with similar temperature profile as immersion.
I don't recommend a press pot, because it kinda requires its own grind level.
------------------------------------------ ----------------------------------------- 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
jpender Senior Member Joined: 11 Jul 2011 Posts: 428 Location: California Expertise: I like coffee
Grinder: Kyocera CM-50 Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Fri Jun 15, 2012, 9:47am Subject: Re: Coffee Extraction Discussion, Questions for the membership:
Netphilosopher Said:
It's something I've been thinking about and turning over in my head (and attempting in practice). I figured I'd try and re-create the experiment with percolation method - but it's impossible to apply the same brew parameters to higher brew ratios in a pass-through gravity drip percolation method with same size filter like you can in immersion.
I'm not sure what experiment you're talking about now. But if you're pushing brew ratios really high why can't you settle for the range that your device is designed to handle?
Netphilosopher Said:
...even though the brew charts don't show it, brew ratio (except for the new charts - by Bunn - they actually show an adjustment in the brew chart around the optimum brew range weirdly spread out).
The first one matches the SCAA chart, the numbers are just changed. The second one appears to imply that more water is lost or retained by the grounds for high and low brew ratios, but not for medium brew ratios where they agree with the SCAA. Why would that be? Given that they are inconsistent on their own website could this chart be a mistake?
Netphilosopher Said:
IF "extraction is extraction", then they SHOULD yield darn near the exact same strength, right? Same contact time, same grind, same brew ratio, same coffee, same brew chart.
If they actually extract the same percentage of solubles and retain the same percentage of water then sure, I don't see why not. But what if they don't extract exactly the same? There are other variables besides the ones you listed.
To be honest I'm not sure what you're trying to do.
Posted Fri Jun 15, 2012, 3:02pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
jpender Said:
I'm not sure what experiment you're talking about now. But if you're pushing brew ratios really high why can't you settle for the range that your device is designed to handle?
The experiment that started this thread. 18 randomized brewed cups of coffee at 3 different brew parameters (combined grind and contact time), 3 different brew ratios by 1 replication.
And exactly what's the range for my AeroPress? :D (answer: whatever I want it to be)
jpender Said:
Which chart by Bunn? I've seen two on their website and they're different.
The first one matches the SCAA chart, the numbers are just changed. The second one appears to imply that more water is lost or retained by the grounds for high and low brew ratios, but not for medium brew ratios where they agree with the SCAA. Why would that be? Given that they are inconsistent on their own website could this chart be a mistake?
Well, we all seem to have taken this inferred value - "extraction" - and treated it like a "measured" value. There is NO WAY to measure extraction exactly. We can only use measurement of strength and back calculate, or measure combined solids (dissolved and undissolved), or measure remaining undissolved solids.
We've also taken at face value that extraction has this special range, and that it is a proxy for taste. But because we put a number to it we trust a number - even a potentially miscalculated one - rather than our own taste.
I've tasted coffee so many times now that's overextracted, but will never backcalculate as overextracted. The brew ratios and "normal" brew parameters that produced ideal tasting coffee do not result in strengths that the brew charts would predict.
I'm just trying to figure out why I can produce bitter/astringent tasting coffee which calculates as underextracted, or near-ideally extracted. Also I'm trying to figure out why nobody is bothered by an extraction measurement method that is wholly dependent on how much coffee I decide to press out of the spent grounds, or how much coffee I decide to "yield" (i.e. how much cowboy coffee I decant, or how much of my Press Pot I "produce" because I hate dregs).
The brew charts are not valid for all brew methods. Extraordinary claim (since the brew control chart has been taken as gospel since the 60's), and requires extraordinary effort to dispute.
(Click for larger image)
------------------------------------------ ----------------------------------------- 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
The brew chart is just a graphical depiction of mass conservation. You start with coffee and water and you end up with the same amount of each just distributed differently. If we all used the same mass units and agreed on the same absorption factor we'd all draw the exact same chart. How brew ratio affects extraction is irrelevent.
In reality the absorption factor is variable depending on brew method. The SCAA chart assumes a constant absorption factor. But the Bunn chart implies that the absorption is larger for high and low brew ratios than for medium ratios.
How can that possibly make sense?
Netphilosopher Said:
Well, we all seem to have taken this inferred value - "extraction" - and treated it like a "measured" value. There is NO WAY to measure extraction exactly.
I know you mean effective extraction here, not the usual meaning. And I agree with you that measuring it is problematic for the simple reason that "it" isn't defined well. What exactly determines the difference between solubles in the grounds that are extracted and solubles in the grounds that are not extracted? How do you draw that line?
I think you can work out a formula or chart or rule of thumb despite this limitation. Actually, I thought you already had. Doesn't the simple formula you posted a while back work reasonably well?
Posted Tue Jun 19, 2012, 6:12am Subject: Re: Coffee Extraction Discussion, Questions for the membership:
Anyone ever setup a drip brewer, then sample the stream and measure strength from the basket at 30 second intervals before?
I'll tell you, it's very enlightening. Methinks a lot of people reprint charts without the experience behind it.
It was worth the couple hours I spent doing it. LOL
(Click for larger image)
------------------------------------------ ----------------------------------------- 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
j123 Senior Member Joined: 15 Sep 2009 Posts: 56 Location: US Expertise: Just starting
Posted Sun Jun 24, 2012, 8:15pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
Netphilosopher Said:
tasted coffee so many times now that's overextracted, but will never backcalculate as overextracted. The brew ratios and "normal" brew parameters that produced ideal tasting coffee do not result in strengths that the brew charts would predict.
I'm just trying to figure out why I can produce bitter/astringent tasting coffee which calculates as underextracted, or near-ideally extracted.
I've been following this thread with interest as someone who frequents a pour over cafe but was never able to duplicate the same results at home with all the same equipment/materials with the exception of the grinder.
after many experiments and different levels of extraction, the only thing I could conclude was that I was getting uneven extraction that, as a whole when measured, averaged to appropriate extraction.
do you think that the inherit uneven grind could account for your above observation?
Posted Mon Jun 25, 2012, 5:16am Subject: Re: Coffee Extraction Discussion, Questions for the membership:
j123 Said:
I've been following this thread with interest as someone who frequents a pour over cafe but was never able to duplicate the same results at home with all the same equipment/materials with the exception of the grinder.
after many experiments and different levels of extraction, the only thing I could conclude was that I was getting uneven extraction that, as a whole when measured, averaged to appropriate extraction.
do you think that the inherit uneven grind could account for your above observation?
I've tried using Ditting settings to correlate too. I don't have a sieve set (yet) but I've done some quick checking with a screen, and have a general idea where a setting of 9 and a setting of 4.5 on a Ditting are (just general). Similar strength results, my Bodum maybe has about 10% more fines than a comparable Ditting setting. Maybe. Talking about a difference of 8 to 9 grams in 100 grams of grounds.
Issue is, however, even using fine grind, I'm still unable to produce a technical yield-calculated overextraction.
No matter what method, in the following:
Cp = Wb - (A * C)
A (the absorption ratio used to predict produced coffee or yielded coffee) is between 1 and 3.2 (the higher values are for methods with REALLY wet grounds, like a press pot).
So, assume you're able to wring the maximum production of coffee from your device (A=1), using 20g of coffee to 250g water (Brew Ratio 16:1 or 8%):
Cp = 250 - (1 * 20) = 230g coffee. To get 20% extraction, the strength needs to be 4g TDS dissolved into that 230 g or 1.74%
So, now there's a target strength range - because at 22% extraction, I'm looking for a strength of 1.91%, and if I figure the maximum extraction available is around 26%, I'd be getting strengths around 2.26%, right?
Now, the only question is what brewing parameters at this brew ratio (contact time, grind, temperature) will get me overextracted? The answer is pretty simple: long, fine, and high. Easy as pie, right?
Try it. If you're lucky - you might use espresso grind, get a well extracting coffee varietal, and let it soak overnight and maybe get a strength of 1.85% or 1.9%.
Try it on the sifted fines, even. Let me know if you find something that when run with this brew ratio gets a strength of over 2%.
Keep in mind this is for full contact methods. Use same brew ratio with long contact times on a fine grind on pourover, and you can absolutely get some pretty overextracted stuff. If my goal was to overextract ALL of the coffee, then uneven extraction is irrelevant - it should achieve overextraction for all of the 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
Posted Mon Dec 10, 2012, 11:33am Subject: Re: Coffee Extraction Discussion, Questions for the membership:
Adding some pertinent information.
My basic reason for doing this initial 18-run experiment was to see how strength is controlled by the brew parameters. A lot of people have asked me how this relates to my ability to predict.
There are two things going on, or two directions to think about this experiment, or how we brew coffee at all.
1) we know the brew water, brew coffee (and by calculation the water brew ratio), and for these aeropress immersion brews, the contact time and grind level. We brew the coffee, measure the strength and through an assumed model we back calculate extraction.
or
2) we know the W,C,R, contact time and grind level, and we make the assumption that extraction is controlled by the contact time and grind level, and by controlling R and E we obtain a specific strength.
The problem with modeling 1 above is that there is no explicit and independent measurement of "extraction" or in the case of immersion brewing "dissolution". We can only mathematically infer it from the resulting strength.
The assumptions going forward are the brew parameters of grind and contact time, regardless of brew ratio, are the variables that control extraction, so I essentially set the experiment to have three levels of extraction (really "dissolution"). The actual levels are averaged for each of the 6 runs based on the model for the relationship of immersion/infusion/steep brewing:
S=E/(R+E), which inverts to E=(S*R)/(1-S)
So, for each run, we have W, C, and an assumed extraction based on grind level and contact time. We can then use those three levels of extraction to predict strength based solely on E and R for all runs.
I've plotted the prediction, along with the 1 slope line. For the variables both controlled and uncontrolled in this experiment, I'd say this simple model describes the system well.
(Click for larger image)
------------------------------------------ ----------------------------------------- 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 Dec 10, 2012, 12:10pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
Now, it IS possible to develop a very complicated model and assume that as the water brew ratio gets stronger (i.e. it gets numerically lower) then a yield-based extraction COULD be established. A quick check of the data shows that the variance does not seem to match within even reasonably expected parameters.
For example, the fine grind 8 minute steep for the three brew ratios show significant differences in yield-based calculations (where E = (P * S)/C), yet all have a very similar (you'll have to take my word for it) flavor profile. In other words, they taste overextracted - yet they range from 18% to only 22% extraction. (for all three brew ratios, the extraction calculation immersion method shows these as nearly constant).
It also becomes recursively difficult to construct a model where the extraction is changed by the brew ratio, which alters the absorption (because yield-based calculation is dependent on some absorption term) for models where the absorption has an extraction component...
Here's what the extraction looks like for yield-based extraction calculation. Notice that as the brew ratio gets stronger, the extraction gets lower - but it becomes difficult to come up with the model that would account for this, as well as the taste notes which are a long way off from traditional "extraction" preferences. 8 minutes steep on fine grind to only achieve 22% extraction seems out of place.
(Click for larger image)
------------------------------------------ ----------------------------------------- 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
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
![Netphilosopher: BrewChartComparison.jpg](javascript:ImagePopup("/images/57846/BrewChartComparison.jpg", 432, 450, "Netphilosopher: BrewChartComparison.jpg");)
![Netphilosopher: DripSampling_ .jpg](javascript:ImagePopup("/images/57867/DripSampling_.jpg", 500, 359, "Netphilosopher: DripSampling_ .jpg");)
![Netphilosopher: Predicted Strength for all runs.jpg](javascript:ImagePopup("/images/59604/PredictedStrengthforallruns.jpg", 481, 289, "Netphilosopher: Predicted Strength for all runs.jpg");)
![Netphilosopher: Yield Extraction for all runs vs R.jpg](javascript:ImagePopup("/images/59606/YieldExtractionforallrunsvsR.jpg", 481, 289, "Netphilosopher: Yield Extraction for all runs vs R.jpg");)
= No New Posts since last visit 