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January 30, 2017 /
VST,WTF Part 3

 

The Coffee Control Chart

This is the part of my presentation where Baristas lose focus and eyes glaze over. “Graphs? Numbers? I don’t need those. They’re scary. It’s all about the feels!” they say. Well perk up, because thoroughly understanding the coffee control chart (CCC) and holding it in your mind’s eye is super important for coffee awesomeness.

Note: You don’t need a refractometer to benefit from this information! Not owning a refractometer doesn’t mean the rules don’t apply to you.

The chart above can be overwhelming at first glance, so I’m going to break it down and show you how easy it is to understand.

We have two axes: horizontal is Extraction and vertical is Strength. Extraction is the percentage of the dry coffee mass you dissolved in the water (aka ‘solubles yield’). Strength is the Total Dissolved Solids of the brew (aka TDS%, total dissolved solids or solubles concentration).

Every coffee that has ever been brewed sits somewhere on the CCC. It caters to every combination of strength and extraction. This might seem bleedingly obvious, but it pays to think of the chart as an infinite canvas on which every coffee can be communicated.

Taking a step back from infinite, we get to 99.99% of every coffee ever brewed. Coffee rarely (if ever) exceeds 30% extraction, and brewing espresso above 20%TDS would require the rizziest ristretto ever dared, which leaves us within these bounds.

Zooming in a little further, and we find there are two distinct zones covering the vast majority of coffees.The red zone covers most espressos, and the blue zone covers most drip/filter coffee. When you make americanos, bypass brews or similar they’d sit somewhere between them, in what has been coined the ‘twilight zone’ of TDS.

I also have a ‘zone of deliciousness’ that encompasses an overwhelming majority of coffees I’ve measured that I think are delightful. Notice I’ve thrown in a little extra box between 3.5 and 4.5%TDS – I’m quite partial to an americano diluted to this range.

Various coffee bodies around the world have published their own zones for strength and extraction preference. Just like my own above, these zones don’t necessarily agree with you or your situation. As always, I recommend experimenting with abandon.

Sometimes you’ll see a few lines thrown onto the CCC. These represent the possible combinations of strength and extraction you could achieve from a fixed brewing ratio (40g, 50g, etc. coffee per liter of water). Once you’re working with a set ratio of coffee to water, your potential destinations on CCC are restricted to one of these lines.

This is really useful. Instead of throwing a dart at an infinite canvas of strength and extraction, a brewing ratio can restrict your brew to a two-dimensional line. If we apply my personal zone of deliciousness to the chart, we immediately see that some brewing ratios will never achieve happiness (40-45g), some have very little chance (50 and 70g), while others strike right through the heart (55-65g). It’s with these brewing ratios that I approach nearly every coffee I come across because they’re most likely to succeed.

With drip/filter coffee it’s really easy to navigate the CCC because it’s easy to fix your brewing ratio. Espresso, on the other hand, is much less intuitive. Next week I’ll be detailing some simple methods for navigating the CCC with each brewing method.

 

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Anthony
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Anthony

so… is there a part 4?

Mike Troup
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Mike Troup

There seem to be two ideas of what a ristretto is – an espresso where the cup is removed early; and on the other hand a finer grind so that the water is slowed so much it actually takes longer for a smaller volume to come through – see Al’s rule. The former will of course almost always taste under extracted. Any thoughts?

writefish
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writefish

Perhaps he refers to the fact that the line moves along both the X and Y axes, indicating two coordinates (Cartesian?) that inform the strength and TDS of the finished cup. As such, by confining oneself to the lines, the parameters available are limited to grind size, if I understand correctly, and ratio of dry coffee to liquid extractant (water, of course). Length of extraction then becomes, rather than a parameter to be rigidly adhered to, an informative indicator– i.e. overly long? Grind more coarsely. Overly short? Grind more finely. As it happens, just brewed a cup with an adjusted… Read more »

baldheadracing
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baldheadracing

Turkish is in the “Twilight Zone.” Cool.

AndyS
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AndyS

“…a brewing ratio can restrict your brew to a two-dimensional line.”
I understand your point in the context of the article, but by definition there’s no such thing as a two-dimensional line; lines are one dimensional

writefish
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writefish

My understanding of ristretto is along the lines of your second definition. “This is done by using les brewing water for the same amount of ground coffee. The grind of the coffee should be finer so the brew time remains long enough to extract all the desira ble aromatics from the coffee.” (Hoffman, James; The World Atlas of Coffee; Firefly; Bates, Denise ed.; copyright 2015) Seems that a real-world experiment would quickly prove you correct in your assumption that the first method would produce under-extraction. Very helpful per Andy S. And Scott Rao to use mass of the extracted shot,… Read more »

Mike Troup
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Mike Troup

This is interesting: https://www.home-barista.com/espresso-guide-good-extractions.html
The implication is that drinks with the same extraction ratios can have different ranges of dissolved solids so can taste very different, not simply more/less concentrated. So for a ristretto: finer grind, less water, more time, more concentrated, sweeter. Have I got this right? And a lungo, rather than just being an espresso diluted with hot water, would be: coarser grind, more water, less time, less concentrated, more bitter.

Mark Burness
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Mark Burness

The brew ratio lines only apply to any kind of brew in certain circumstances, but most typically drip. They are guide to what might be typical, not what is/isn’t possible. Your immersion calculation in Coffeetools is slightly different to the drip style chart above (note modes for drip or immersion), your Aeropress result doesn’t seem wildly out of the norm.

mattymooners
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mattymooners

do the brew ratio lines apply to immersion brewing? today I brewed a 69g/L immersion (aeropress) at 1.5 TDS and 23.31% EY… according to the chart this isn’t possible!

Mike Troup
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Mike Troup

So the idea that a ristretto has a different flavour profile – and less caffeine – from an espresso is false – it is just more concentrated?

Gregory Levine
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Gregory Levine

I’m confused. Why do I need a refractometer if I know brew ratio and TDS? can’t I just put that data into the chart and solve for extraction %?

Mark Burness
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Mark Burness

By the time you have added the full amount of brew water to a drip/filter brew at 65g/l (assuming you have ground the beans) & let all the water drip through, it is highly likely that the range of extraction & strength will be narrowed some, it’s pretty easy to hit around 15%EY up to 23-24%EY (0.2%TDS would be impossible in practice at 65g/l & 27%EY unlikely in normal circumstances), but there will be areas of high & low preference scattered across that range, with a much narrower range of very high preference. That chart was plotted by dehydrating coffee… Read more »

Christopher Schaefer
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Christopher Schaefer

What tools do I need, then if not abrefractometer, to measure Extraction and Strength?

Gabriel Burian-Mohr
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Gabriel Burian-Mohr

I am confused about how one plots the diagonal lines. I am assuming that the numbers at the top, i.e. 75g, 65g, 60g, etc., indicate the ratio grams:liters. So, for example, 65g would translate to 65 grams of ground coffee to 1 liter of water, or 65 grams of ground coffee to 1000 grams of water, or 1 gram of ground coffee to 16.666 grams of water. Okay, but where do these lines start and end? How do I determine that the line for 60g starts at 0.2 on the TDS axis and continues through 27% on the extraction axis?

AndyS
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AndyS

You know the brew ratio (if you brewed the coffee attentively). But you don’t know the TDS without a refractometer. Once you measure the TDS with the refract you find that number on the vertical axis. Then continue horizontally until you hit the brew formula line that’s closest to the actual brew ratio you used. Once you hit the correct line you go vertically down to read your Extraction %.

Gabriel Burian-Mohr
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Gabriel Burian-Mohr

Oh, I see it now! Thank you. I have been taking readings and plotting them in an Excel chart for a few months now, and after I read your explanation, and looked at my chart, I can see how the points correspond (approximately). I am just using a cheap refractometer, but there is a clear correlation. Thank you again.

writefish
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writefish

Yes. That’s my understanding also. Thanks for the link. In fact the tds can serve as a guide to adjust the brew ratio and grind, rather than the other way around. That’s why it is important. Hands-on will reveal that the flavor changes pronouncedly when making these adjustments to bring the brew into the optimum range. Also note that optimum is an agreed-upon range (I find it to be pretty accurate) and that those with individual taste preferences might re-define “optimum.” Also, may I add that I’m not a real expert– just an enthusiastic amateur practitioner who roasts, grinds, and… Read more »

writefish
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writefish

You do need a refractometer. Some have suggested using optical refracts which are much less expensive though some also consider them less effective You can pick them up for less than $20 online. Be sure and get one with a metal, rather than a plastic body. Also make sure the model you get has temperature compensation. For pourover use one with a scale from 10 to 20, for espresso, 1 to 50. Calibration is necessary with each use, though it is a very simple process and, if the device is used in similar conditions one often find that it remains… Read more »

Walter97759
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Walter97759

Great explanation, this whole series has been well put together. Thanks Matt

Mike Troup
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Mike Troup

If by balanced extraction you mean the same balance as in an espresso, then what is the point of playing with the grind size to make a lungo, when you could simply add hot water? I can see the point of changing grind size for a ristretto that has the same balance as an espresso but is more concentrated, as there is no other way of lessening the water volume.
What do most cafes do for a lungo/long black/americano? I suspect most do not distinguish between these three, and add hot water before or after the espresso.

AndyS
Guest
AndyS

For a ristretto: finer grind, less water, more time, more concentrated, not necessarily sweeter. And a lungo: coarser grind, more water, less time, less concentrated, not necessarily more bitter. By adjusting dose and grind one tries to get a balanced extraction whether it’s ristretto or lungo — neither unsweet nor too bitter, .

Gregory Levine
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Gregory Levine

Never mind. My conductivity meter gives wildly different readings depending on the temp. Even when the thermometer gets up to temp. Anybody have a workaround for this?

Gregory Levine
Guest
Gregory Levine

Why won’t a conductivity meter work? Doesn’t it also measured the amount of dissolved solid in water as well?

Matt Perger
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Matt Perger

Thanks Walter! 🙂

Mike Troup
Guest
Mike Troup

Interesting. I read a comment about a chap who ran a cafe in Vancouver – in 3 years he had been asked for a ristretto once! He felt that most ristretto requesters just wanted to be sure they did not get a lungo, and were happy with a plain espresso. I have yet to request a ristretto, though I do experiment with them at home. When out I usually have a macchiato followed by a “longer” espresso of whatever variety the cafe provides. Went to a Michelin starred restaurant last night for a major wedding anniversary – something I only… Read more »

AndyS
Guest
AndyS

Within the range that most tasters would call “balanced,” there is still a wide variation in flavor. I’m not sure if there is a point other than personal preference. With regard to cafes making lungos/long blacks/americanos, it’s challenging enough for them to consistently produce a good espresso. Playing with grind adjustments to produce good lungos or ristrettos is what home baristas do, but it’s very rare in real world cafes to do this on the fly. A few years ago there was a fad where faux “experts” (who knew just enough about espresso to be ridiculous) would walk into a… Read more »

Matt Perger
Guest
Matt Perger

Yeah conductivity will never work for coffee. The _only_ way is with a refractometer or dehydration.

Matt Perger
Guest
Matt Perger

True. Damn!

Matt Perger
Guest
Matt Perger

You’re right. Immersion (where all coffee and water are together for the majority of the extraction) sit in a different spot. I’ll be covering this difference soon!

Matt Perger
Guest
Matt Perger

Thanks Mark. And yes Gabriel, nice job on keeping all the data. You’ve got it figured out! 🙂

Matt Perger
Guest
Matt Perger

Analog refractometers don’t have a coffee scale, so they’ll be inaccurate at almost all times.

Christopher – the only ways to measure tds/extraction with any accuracy are dehydration and refractometry. The level of scale accuracy you need for dehydration is much more expensive than a refractometer though.

Peter Houmann
Guest
Peter Houmann

True. Time to apply for some lab time!

Matt Perger
Guest
Matt Perger

Perhaps there would be a correlation, but you’d have to figure it out by running an exhaustive barrage of dehydration or refraction tests in tandem

Peter Houmann
Guest
Peter Houmann

If I had access to a spectrophotometer in a university chemistry lab, could I theoretically obtain the same information as a refractometer?

Matt Perger
Guest
Matt Perger

I (and a few other baristas) have been known not to honour the ristretto request verbally, but keep them happy by just siphoning a few mls out of a regular espresso. They see it’s smaller, and enjoy the drink – usually telling me/us that it’s the best they’ve had.

Matt Perger
Guest
Matt Perger

Because there’s organic (non-conductive) matter in coffee, which isn’t picked up by the meter. And organic/non-organic never exist in predictable proportions to each other. The conductivity meter is pretty useless.

Gregory Levine
Guest
Gregory Levine

My friend who I got the conductivity meter from is a professional lab manager. He said their procedure is to always measure samples at room temp. Why wouldn’t this work for coffee?

Garron Kyle Park
Guest
Garron Kyle Park

Does the brewing ratio stay fixed across extraction percentage? Does it always plot as a straight line? If it’s not likely to rise above 30% extraction wouldn’t the ratio line curve upwards the right of the graph?

Gregory Levine
Guest
Gregory Levine

That makes a lot of sense. Guess I’ll just go back to using that pink thing in my face for now.

FiDi Man
Guest
FiDi Man

Matt – slightly off topic – but regarding the VST software – do you know how the LRR works in the software, as I cannot get my logic to come out as the same as their results – so if I have 408g of water in, 24g of dry bean with a LRR of 2.1 I would of expected 50.4g of water to be retained in the spent bean and a final beverage weight of 357.6g – while the software tells me a final beverage weight of 365g or 43g water retained – so an overall 2% difference. Wondered if… Read more »

Jenna Elise
Guest
Jenna Elise

Congrats on the Sprudgie!! Knew you’d win it!!

Matt Perger
Guest
Matt Perger

If the line curved upward, then you somehow achieved a strength gain without increasing extraction. Quite impossible.

Kyle Joel Hood
Guest
Kyle Joel Hood

Or would the line drop down because strength would plummet (or simply cut off) if you continue to try to extract more than 30%? Those lines can’t continue on indefinitely.

Martijn Brouwer
Guest
Martijn Brouwer

Re: ristretto. In Melbourne Australia every barista I know just gives the first 15ml of the espresso. No one in a working environment will disrupt their workflow just to change the grind just for you.
I have two thoughts: Without changing the grind you could either tamp really hard or overdose it, in both ways restricting the waterflow.
In either case you would move away from the theory behind good extraction.
(I sometimes feel that someone ordering ristretto gets more satisfaction from being the only one that orders it than from having a great product.)

Bobby H. Christ
Guest
Bobby H. Christ

Gabriel, That is spectacular. Would you mind sharing your spreadsheets/charts? I’ve been tracking my brews each morning for close to a week. I’m using a TDS spreadsheet from Mike Khan at the Bunn lab. It works but I suck at excel and don’t know how to chart the data like you have done. That is outstanding.

Garron Kyle Park
Guest
Garron Kyle Park

Are TDS and Extraction perfectly correlated?

Matt Perger
Guest
Matt Perger

It really is the best.

Martijn Brouwer
Guest
Martijn Brouwer

In the Melbourne cafe I work at, and some that I know:
Lungo is not on the menu because you would need a separate grinder for it,
Long Black is hot water with a double espresso on top in a stoneware cup with an ear, Americano is hot water with a single espresso on top in a duralex glass.

DonLaLinea
Guest
DonLaLinea

If I use 15 gramm dose for an espresso of 30 gramm yield, I get a ratio per lieter of 500 gramm (15gr/30gr*1000gr=500gr). There is no such figure on the chart. Am I doing something wrong?

writefish
Guest
writefish

No, no coffee scale per se, but some have suggested a conversion of 0.85 times the brix percentage to yield tds. Organoleptic sampling lends at least some credence to this.

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