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January 30, 2017 /
The Most Important Thing About Brewing Coffee

This week I’d like to explain the concept of an even extraction, and what it means for flavour. The rabbit hole of evenness goes really really deep. I’m going to devote a number of weeks to discussing it. I want to drill right down into green coffee, roasting, grinding and brewing from the very specific viewpoint of evenness. Evenness is likely much more important than you have ever given it credit for. I hope to change that!

Throughout my Barista career, so many of my teachers and peers have told me to extract evenly. “Don’t do x or the extraction won’t be even” and “Do y to even out the extraction” etc. but I never really understood what an even extraction meant, and how it affected the flavour of a coffee. It’s one of those things that gets passed on mindlessly because it sounds good. So what is evenness anyway?

As I mentioned in the very first hustle, extraction is kind of like a two way street. At one end is over-extraction, and at the other end is under-extraction. Our goal, it seems, is to find the magical spot in the middle where everything tastes good so we can call it a day. Unfortunately this isn’t so accurate.

Every coffee grind is a slightly different size and shape, experiences a different flow and duration of water, and comes from a slightly different portion of the coffee bean. This means that every brew is a mixture of hundreds and thousands of individual tiny micro-extractions. Some are extracted more, some are extracted less, some sit in the middle. It’s this cacophonous mix of different extractions that all work together to make a cup of coffee. When we measure an extraction or talk about an extraction, we’re using the average of all of these micro-extractions to give us a number or general zone. Every single coffee that has ever been brewed by anyone is at least a little bit uneven. A sobering fact indeed.

An even extraction is obviously one where all (or at least a majority) of these micro-extractions sit closely together. Hopefully at a point where things are delicious.

An uneven extraction is one where there is a significant difference between large portions of these micro-extractions. This results in a cup that tastes like at least two of the three typical extractions – over, under or ideal – and everything inbetween.

We’re going to brew an imaginary plunger (french press!). In it, you pour 30g of a very fine grind, and 30g of a very coarse grind. You pour 1 litre of boiling hot water in, stir it all around, and wait 1 minute. At the end of that 1 minute you have a really uneven extraction. Half of the grinds will be completely extracted, and the other half’s exterior surface area will be extracted, while their interior will still be hopelessly under-extracted. This is textbook uneven extraction; there are significant portions of coffee grinds that are sitting at different levels of extraction.

.

Let’s think about this plunger as if it were sitting on Extraction Street. It’s not just a point on a line anymore. It’s actually a range of extractions along that line simultaneously. Some of it is over, under and ideally extracted at the same time. It’s a street, so I’ll be using cars to communicate where a brew is. Obviously.

That limo is sitting across lots of different zones of extraction. Not ideal.

[Hustle Nomenclature] I like to call this span or range the “extraction spectrum”. An uneven extraction has a wide spectrum. An even extraction has a narrow spectrum. I’m going to use this term from time to time because it greatly simplifies sentences about complex stuff. That, and I enjoy the word nomenclature. Nomenclature.

The shape of the spectrum (car) can move around the scale to describe any kind of extraction. But the total size of this spectrum doesn’t change. That’s really important. The shape we’re seeing represents the whole brew. If more of the micro-extractions are ideal then it’s thicker at that point. If there’s lots of over-extraction then it’s thicker up there instead. So obviously the most ideal extraction would be very thick at the sweet spot right before over-extraction. This would be considered a perfectly even and indescribably delightful cup of coffee. Rest assured, you’ve never had anything close to it. Bummer.

Extraction Street vertical Limo This doesn’t happen. Most extractions look more like the following. A bit of over-extraction, an ok amount of even extraction and less under-extraction. It’s kind of like one of those awkwardly aerodynamic solar cars. Or those weird cycling helmets. Extraction Street SolarThe problem here is that this shape of extraction spectrum is kind of non-negotiable. You can’t just press the “more even” button on your grinder. Your particular combination of coffee/grinder/brewer/technique is creating that unevenness. If you extract more, the spectrum moves along the line and more of it becomes over-extracted. If you reduce the extraction, there is less over-extraction but less of the coffee is sitting at the sweetest point. The flowchart from last week aims to move this spectrum to the point where there’s the most coffee sitting at the sweetest point, without too much over-extraction. Use it.

So our goal is to make this spectrum as tight as possible. Because then more of it can exist at the sweetest spot. Every time you improve the evenness of an extraction, you move more of the coffee into the most delicious zone of extraction. This means you get more delicious flavours

. coffee extraction animation

You’re moving that coffee from a point where it contributes bad flavour to a point where it contributes good flavour! This means that for every micro-extraction that becomes even, there’s a +1 for good flavour AND a -1 for bad flavour. That’s a +2 level up for Deliciousness!!

Are you with me here? 1 unit of evenness = 2 units of deliciousness. More good stuff and less bad stuff at the same time. How many times have you ever made one improvement to coffee and received two-times the results? It’s magic. It’s the best. I’m obsessed with it. Evenness is incredible: get on board.

I really need to impress upon everyone reading this just how important evenness is for flavour. So here’s my favorite example.

VHS was really great. We got to see movies and hear sound at the same time. Then along came DVD. And Blu-ray. “Whoa” we all said, “VHS is so terrible!“. The movies didn’t change. The story-telling was the same, the actors were still beautiful. But the image and sound, the experience, was so much clearer and detailed! This is a super close analogue to the difference you experience when going from an uneven extraction to an even extraction. It’s the same coffee, with the same flavours. But now you’re getting so much more clarity, transparency and intensity of interesting flavours and so much less distracting and muddling dryness, sourness and other extraction taints.

Belle

Belle in delicious High Definition, vs crummy old DVD. Kind of like going from conical to flat burrs?

Remember in the first Hustle when I talked about extraction faults being generic? They’re boring and don’t taste like the coffee you’re actually trying to present. An even extraction reduces the amount of generic, boring extraction taints and replaces them with delicious, sweet, complex and ideal extraction flavours! This is Specialty Coffee after all. We want our customers to pay more for a premium product. Even extractions deliver them more premium flavour.

The beauty of an even extraction is startling. It’s like someone has lifted the veil on a coffee.

Have you ever been frustrated with an espresso because it tastes like… espresso? That typical, boring “espresso” flavour you can’t get rid of. And behind it there are these hints of acid or sweetness but they’re not strong enough to really take shape or be identified. Well, an even extraction scrubs that generic flavour away and replaces it with the those delightful background flavours. They’re now in the fore. Instead of a coffee that “kind of tastes a bit tart” you now have an coffee that “tastes like I’m biting into a Ramson plum that’s perfectly ripe and has wonderful crystalline sweetness and perfumed skin”. It’s amazing. Who wouldn’t want this?

Tighten your extraction spectrum and deliver your customers a coffee that truly represents its provenance, rather than under or over-extraction. Make your extractions more even and the coffee will be better, every time. It’s the most important thing about brewing coffee!!

The next few hustles will be devoted to evenness. In depth at the farm, roasting, grinding and brewing stages. Get ready!

 

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Is it Better to Sieve out Particles Smaller than 400μm? - Barista Hustle

[…] If you’re finding this development confusing, you’re not the only one! However, the apparent contradiction is resolved when instead of thinking about ‘fines’ and ‘boulders’ we go back and look closely at what it is we’re trying to achieve — an even extraction. For a quick reminder on why this is so important to flavour, take a look at this post from the archives. […]

Sergey Sorochanov
Guest
Sergey Sorochanov

Great read! Thanks! So conical burrs are really that bad ?)

Kostas Sideris
Guest
Kostas Sideris

Not all conical grinders deliver the same shape, or even grind distribution… It depends on quality of the burrs, how accurate and centered are the burrs, among many other things. Flat burrs are just more forgiving on manufacturer’s mistakes. I may analyze these facts on a post myself!

Melanie Weldert
Guest
Melanie Weldert

Love it!!! Thx so much. I would like to know more about pre infution in a frensh press or aeropres, is it necesary? Im one of that persosn who thinks its not. What do you think?

Mat North
Guest
Mat North

Ah evenness, the holy grail of extraction. intrigued to see where this goes in the next few weeks for sure there are so many factors at play that it’s almost impractical to control them all, the best we can do is work with those variables that we can affect.

Linh Nguyën
Guest
Linh Nguyën

This is like Lost all over again. Cliffhangers all the way! ;P

Kyle
Guest
Kyle

conical burrs will give you an almond/rugby ball shaped grind particle..
so its fat in the middle and narrow on the ends, this will mean you are
extracting more from the ends of your grind and not enough from the
middle.. this means uneven extraction. hope that was a clear
explanation??

Alistair Pace
Guest
Alistair Pace

<3

Extracting a Mean for the Coffee Bean | Reason & Existenz
Guest
Extracting a Mean for the Coffee Bean | Reason & Existenz

[…] via The Most Important Thing About Brewing Coffee – Matt Perger. […]

Ben
Guest
Ben

I realise I’m jumping the gun a bit but for filter coffee what sieve size could one use to reduce the amount of fines (for a grinder that produces a lot)? Do you find it more rewarding to reduce fines or boulders? Thanks Matt, I’m looking forward to the Hustle every week!

Ross
Guest
Ross

Hi Matt – I have a Mazzer mini would you say that gives an even grind size?

Sergey Sorochanov
Guest
Sergey Sorochanov

I’m no Matt, but I think somewhere he mentioned about using a 250µ sieve. Also, under his pourover vid he said that we need the small ones much more than the big ones, so get rid of the boulders also)

Figo Luo
Guest
Figo Luo

Thanks, Matt! It’s a great read. According to this,could I say that if I want to narrow down the spectrum the only thing I can do is to grind the coffee more evenly?

David Smith
Guest
David Smith

really looking forward to hearing your thoughts on eveness through roast development. especially your thoughts on extraction eveness in relation to coffee BLENDS.
“ideally” each origin in that blend is roasted to the perfect amount of development. but on some blends this means each component extracts at a different rate, producing a less controlable extraction window

Matt Perger
Guest
Matt Perger

I’m asking myself this question regularly. I think it’s more of a technique to increase contact time in a pour over.

Matt Perger
Guest
Matt Perger

Thank you! Well, I’ve never had a truly great coffee from conicals. Nor have I ever been able to get a decent extraction from them.

Matt Perger
Guest
Matt Perger

I’ve never tested one thoroughly enough. I would hazard a guess and say mediocre at best.

Sergey Sorochanov
Guest
Sergey Sorochanov

Any thought on the Lido2 by OE ? Rugby-ball shaped ?

Ross
Guest
Ross

Thanks for your reply Matt – What would you recommend if an EK43 was a little big/expensive – just for home use?

Sergey Sorochanov
Guest
Sergey Sorochanov

By not decent you mean undrinkable or not brewers cup level?)

Matt Perger
Guest
Matt Perger

I would just get rid of boulders. Use a tea strainer thats roughly 0.5mm and you’ll knock a lot of the unevenness out!

Matt Perger
Guest
Matt Perger

You have many tools at your disposal. Stay tuned for everything I know!

Matt Perger
Guest
Matt Perger

Yeah this’ll be a big one. I’m looking forward to it too!

Matt Perger
Guest
Matt Perger

I’d go with a vario. I have one for home and it’s delightful!

Kyle Mervau
Guest
Kyle Mervau

In the topic of “evenness” will you be going into (in the brewing section) the conversation of the brewbed post brew? Especially with conical shaped brewers (V60, Chemex) and how level the brewbed is post brew against coffee that remains on the sides of the brewer (creating a deep sunk conical hole)? Or if this is even important at all in terms of brewing and “evenness”? I am thinking about coffee that remains on the sides that drains out before coffee that is lower in the brewer.

Aaron
Guest
Aaron

Hi Matt, How’s the performance of Nuova Simonelli Mythos One with its grind evenness?? Thank You !

djboris
Guest
djboris

Hello, do you prefer or the metal or the ceramic burr for Vario? I have bad experience with both. After almost one year fight I did change it and bought a Lido2. Since that my extraction is much controllable. Regarding particle distribution, looks like the sigma(dev) is smaller. The taste cannot really compare. With Lido much better, and much controllable(the taste). Of course one advantage I did lost, that is the comfort. Maybe it is not a standard case just my experience.

Daryl Grunau
Guest
Daryl Grunau

Thanks for these great articles. Look forward to each email I get notifying me of a new post.

Shaun Spruch
Guest
Shaun Spruch

This is truly awesome! I cannot wait for more practical ways to create this “evenness”!
Just a quick question(although I assume you will deal with it when speaking about roasting) – How much does the origin of the bean and the roast profile affect this overall “deliciousness”? Surely certain coffees, even when extracted at this mostly even point, won’t reach the delicious realm? And one other thing… do you think there are coffees out there which taste better if over extracted or underextracted rather than evenly extracted?
thanks for these amazing articles!

Ben
Guest
Ben

Thanks for putting your time into this…few questions 🙂

1. What’s your favourite water to brew with that you can get in Melbourne?

2. Obviously different for different coffees but when you are doing FILTER coffee and you nail the extraction, what is the ballpark figure for the mode particle size? ie the large peak on the laser diffractometer graph.

3. Leading on from Q2, if you then had the time to use two sieves (to remove fines and boulders) what aperture would they be?

Thanks!

Ross
Guest
Ross

Thanks again Matt 🙂 Looking forward to the next Hustle!

Chris
Guest
Chris

Just to clarify, do you mean Baratza Vario or Mahlkonig K30 Vario?

Ben
Guest
Ben

I have a Lido2. Do you find better results grinding coarser? Are you sifting? Also did you find that it improved after the first few weeks?

Carles
Guest
Carles

Once again enthralling! Does your unevenness theory and specially the issues conical/flat burrs & form of the coffee particles applies for brew and espresso preparation or only for brewing?

Matt Perger
Guest
Matt Perger

Tap water in melbourne is generally pretty great. I like north of the river better.

To be honest, I don’t know. But if I had a choice I’d knock out everything above 350um

Matt Perger
Guest
Matt Perger

Absolutely!

Ben
Guest
Ben

Do you mean like Sarah Anderson did to win the 2015 US Brewers Cup? See link after this word (it’s invisible on my screen) http://sprudgelive.com/?p=243

Mike Shevnin
Guest
Mike Shevnin

Hi Matt!

Thanks for your hustles, they are like a breath of air for me.

You are talking about extraction in terms of taste and flavor. But is there a way to measure it in figures? Does a high TDS automatically mean a great cup?

Another question is to all EK43 users and owners. Is it possible to use it as a main espresso grinder if i sell max 35 cups per hour?

Matt Perger
Guest
Matt Perger

It’s pretty good!

Matt Perger
Guest
Matt Perger

Yes and yes!
A refractometer measures TDS. I’ll be doing heaps on these. It’s my forté.

An EK in that situation is totally fine.

Matt Perger
Guest
Matt Perger

Everything so far mentioned is for any kind of coffee brewing.

Mike Shevnin
Guest
Mike Shevnin

Thanks for your answer!

Then i’m ordering ekk43 for my shop. One side for espresso and other for filter coffee

Ben
Guest
Ben

So are you changing your views with regards to fines and thinking they are not so much of a problem? Was watching your WBrC winning routine and you knocked out everything UNDER 250um then. Am I correct in saying that it’s very hard to use a sieve to knock out everything above 350um, in that if you used that exact sieve size, it would be hard to get all the particles <350um through the sieve because of the varying shapes not fitting through the apertures properly. And that is why you just recommend a tea strainer 500um approx?

Guest
Guest
Guest

Related to the 80:20 method, is it reasonable for FILTER to increase dose as a means of brewing longer to extract more? Background: my grinder (Lido 2 hand grinder) is more consistent and even at coarser grinds therefore with the standard recipe (12g to 200ml) the brew time is too short even using pulse pours.

Matt Perger
Guest
Matt Perger

I think the surprise will be how much better your coffee tastes. Go for it!

Philip
Guest
Philip

I was really excited about the Perfect project, specifically the idea of optical grind analysis. Do we think there will ever be a real-time utility for optical analysis technologies in a cafe? I’m hoping that some day these technologies will be to particle size distribution what scales are to weight.

Or not. Either way.

Sergey Sorochanov
Guest
Sergey Sorochanov

Use hotter water then to bump the extraction or introduce more agitation to your brew. Hope that helps!)

hooshd
Guest
hooshd

Without taking away from your awesome solar car diagrams, the way I understand it is if you’re making a stir fry, you don’t mince the meat & veg too finely (overcooked, too soft), nor do you have huge chunks (undercooked), nor do you have random chunks of all different shapes and sizes (some over cooked, some undercooked and some just right)…

Ilya
Guest
Ilya

Hi Matt!

Would you please tell me all the pros and cons of EK43 vs EKK43, in case I’m working both with espresso and filter coffee, making max 35 cups per hour. What kind of surprise I can get if I start with EKK43 doing my espresso and filter coffee in the same time ?!

Matt Perger
Guest
Matt Perger

I’m constantly changing my views on fines. At the moment, I’m pretty sure they’re the most important and significant part, so it’s better to get rid of boulders rather than fines.

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