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January 30, 2017 /
Coffee Extraction and How to Taste It

This post will cover some basic extraction theory and the tastes associated with over, under and ideal coffee extractions.

Extraction is arguably the most important and least understood aspect of coffee brewing. It’s everything. Without extraction, you don’t even get a cup of coffee. Here’s my super simple and not 100% accurate definition:

Extraction is everything that the water takes from the coffee.

It’s pretty easy to sum up, but a lot more difficult to understand and apply.

For now, I don’t want to delve into fats and lipids and the micro-componentry of extraction. I want to communicate useful and relevant information, like how to taste extraction and how to manipulate it. Chemical analysis can come later.

When you mix coffee and water, a lot of things happen. The most relevant and easy to understand of all these things is that water dissolves a lot of coffee’s flavours. These dissolved flavours make up (almost) everything you taste when you drink a cup of coffee. The rest is undissolved stuff. This is mostly very very small coffee grinds that affect mouthfeel, but can’t be included in extraction because they’re just floating around in the water.

Roasted coffee beans are ~28% (by weight) water-soluble. This means that you can extract ~28% of the coffee bean’s mass in water. The rest is pretty much cellulose and plant stuff that forms the structure of the seed.

Water is pretty good at dissolving those soluble chemicals, but it needs help. If you throw a handful of coffee beans in hot water, you don’t extract much more than the outside layer. This is because the coffee bean’s structure is incredibly dense and complex; water can’t just pass through and collect all the flavour on its way. To help, we have to increase the surface area of the coffee beans; we need to ‘open them up’ so the water can easily get at all of the flavour. This is achieved rather handily by the use of a coffee grinder. It crushes the beans into a powder, exponentially increasing their surface area and allowing the water to do its work.

In an ideal world, we’d crush the coffee into an extremely fine powder, throw water at it and dissolve all of its delicious flavours. Unfortunately, this results in a terribly bitter and awful cup of coffee. Not all of the coffee’s flavours are good, so we have to control the amount of flavour that we extract in order to make a palatable cup.

We also can’t just use more coffee grinds and extract less of them to avoid those over-extracted flavours. Under-extraction tastes terrible as well (more on this in a moment).

Most people understand extraction as a two-way street. A street where we always try to steer the coffee towards the middle; avoiding both over and under-extraction.

For the next two Hustles, this simple analogy will be enough. Then once you’re all over it, I’ll be adding a layer of complexity that rounds everything out. Until then, we’re on two-way Extraction Street!

Coffee Extraction Street Sign

Under-extracted Coffee

Under-extraction occurs when you haven’t taken enough flavour out of the coffee grinds. There’s still a lot left behind that could balance out the following undesirables.

Cast your mind to a shot of espresso that was far too short; a ristretto of a typical Specialty espresso roast. It’s sour, lacking sweetness, weirdly salty and has a disappointingly quick finish. These four things are the most obvious indicators of under-extraction. Let’s go through them in a little more detail.

Sourness –
This is a tricky one, especially with our desire for acidity in coffee. I hear lots of people ask “Aren’t sourness and acidity the same thing?” and it’s a very valid question; in a lot of languages ‘sourness’ is the same word as ‘acidity’. As you can imagine, this makes multilingual cuppings a little difficult.

To clear this up, I always define sourness as being negative. A sour flavour hits you quickly and aggressively. It creates an immediate physiological reaction, you might pucker your lips or it might feel electric or sharp on the sides of the tongue. Sourness is undesirable and distracting.

Whenever I talk about acidity it can be either good or bad. It’s more of a category of flavour than a positive or negative attribute. Example: “That coffee’s acidity is delightful” or “That coffee’s acidity is very sour” are both logical to me. Acidity is the umbrella under which lies all sour/juicy/bright/tart things. I could write volumes about acidity, but this week is all about extraction. Back to it.

Lacking Sweetness –
In my opinion, the most important aspect to a coffee’s flavour is its sweetness. Sweetness is the best. Have you ever heard someone say ‘this espresso is too sweet!’? Think about that for a second. I strongly believe that we should always be chasing sweetness. It’s my holy grail: something that’s really difficult to find and stupendously rewarding once you get it. Under-extraction isn’t sweet. It’s far from it. It almost always displays an emptiness that leaves you with an unsatisfying ‘I-want-more’ feeling after drinking. The good thing about this lack of sweetness is that it also accentuates the sourness, making under-extraction much more obvious.

Salty –
Not everyone agrees with me here, but I’ll argue til I’m red in the face that under-extracted coffee is salty. It’s not quite ‘sorry I added table salt’ salty, but under-extracted coffee almost always has the mouthfeel and/or taste of saltiness. From a tactile point of view, it’s kind of similar to the slipperiness you get from alkalinity (Don’t go and drink ammonia to learn this one. Just trust me).

 

#PocketScience – Acids and Salts are more soluble than Sugars. This is why an under-extracted coffee is sour and salty – the sugars haven’t had enough time or chances to dissolve completely just yet. [citation needed]

 

Quick Finish –
A well extracted coffee has a finish that lingers for minutes (or hours if you’re lucky). This finish can feel as though someone has left dark brown sugar on your tongue, or as though you’ve just finished a toffee. Yum!

An under-extracted coffee doesn’t have this finish. Once you swallow, it disappears straight away. You’re not left with any pleasant lingering sensation. It’s an abrupt and unsatisfying end to your coffee experience. Less Yum.

 

There are other flavours that indicate under-extraction, but these four are certainly the most obvious. Whenever you taste them, be sure that some part of your coffee is under-extracted!

Let’s now cast our attention to the opposite end of Extraction Street.


Over-extracted Coffee

Over-extraction occurs when you take too much of the soluble flavours out of the coffee. This level of extraction results in unfavourable flavours.

Cast your mind now to an espresso of a typical specialty espresso roast that brewed for 40-50 seconds. Don’t pretend like you didn’t taste it when this happened once. It’s bitter, drying and hollow. These three things are the most obvious indicators of over-extraction. Let’s shine some light on them as well.


Bitter –
We’ve all been here. Coffee is bitter. Over-extracted coffee is really bitter. Unless I’m drinking Campari, I don’t want that much bitterness. A lot of this bitterness comes from caffeine, but there’s many other chemicals in coffee that contribute. A darker style roast that has achieved dry distillation will have many more of these bitter chemicals.


#PocketScience – There are thousands of chemicals (pretty much all poisonous) that trigger the exact same bitter signal from our taste buds. This is our body’s way of saying ‘don’t eat that’.

Drying –
Dryness in coffee is so incredibly bad because it’s such a strong sensation, and it can last a long time. This sensation is called astringency and is the same as you get from unsweetened black tea, young red wine or white wines with extended barrel time. In wine, this effect is caused by polyphenols: chemicals that are readily found in plants, seeds, bark etc. These are arguably the same chemicals that cause dryness in coffee.

Polyphenols are bitter and bind to your saliva’s proteins. In layman’s terms, they de-lubricate your tongue, creating a sandpapery or dry sensation in the mouth (This shouldn’t be confused with the wine versions of ‘crisp’ and ‘dry’ – these are terms that denote bright acidity or low sweetness; not necessarily mouthfeel).

Hollow and Empty –
This is a personal descriptor I like to use for over-extraction. The coffee just feels empty and lifeless, like you’ve extracted the living daylights out of it and killed everything in the process.

Well extracted coffee fills your mouth with richness. It’s luscious, smooth and, well, mouthfilling. Over-extracted coffee is empty, hollow, rough and just plain-old yucky. It’s this lack of flavour and character (rather than the presence of a particular flavour) that leads me to use the word ‘hollow’.

Those are the key over-extracted flavours. Of course there are more, but these are super simple to identify, and should have you identifying over-extraction in no time!

The most important thing to note about all of these flavours is that they are generic. You can get them from the most expensive Gesha in the world, and you can get them from sub-commodity grade rubbish. These flavours aren’t desirable. Most of us here are in Specialty Coffee, which means we’re trying to create a product special enough for the customer to want to pay more for it. Extraction-related faults are anything but special.

Now for the sweet spot, the yum-zone, the goods.


Ideally Extracted Coffee

A well extracted coffee is a little miracle. A lot of work has gone into balancing countless variables to produce a tiny cup of deliciousness, and it’s imperative to know what this tastes like.

Cast your mind to the best damn cup of coffee you’ve ever had. It’s sweet and ripe! There’s a clarity to the flavour, like it’s transparent. The acidity is balanced and positive, perhaps complex if you’re lucky. And the finish goes for ever. This is the jam, and you want to know more about it.

Sweet and Ripe –
As I said, the Holy Grail. I’ve spent countless hours teasing more ripeness out of coffees. It never gets old.

Think of a plum or similar stonefruit as it ripens. At first there’s a lot of acidity and tartness, then it gradually gets sweeter. The sugars are developing and becoming richer, heavier, more cloying. Then it hits a point where just holding the fruit near your nose enables you to smell the sweetness. Right there. That’s the sweetness and ripeness you want from coffee. If you’ve never had that, you’re in for a treat one day soon!

Clarity and Transparency –
George Howell has a way with words. He describes the processing method of coffee as being ‘the window through which you see the coffee’. I like to extend this analogy by thinking of the extraction (and roasting) as another pane in that window. If you have over or under-extraction muddying up your glass, it’s harder for you to ‘see’ what the coffee really tastes like. Generic extraction faults are distracting and can impair the provenance of the coffee you’re serving.

Acidity
Fine, complex and definable acidity is truly something to behold in coffee. Acidity is something that’s incredibly beguiling, but also frustratingly flighty. When you get acidity that reminds you of a specific fruit, or even a wine, you’re in the green. If that acidity is so definable and intense that you can pinpoint a variety of fruit and remember the last time you ate it, you’re nailing it.

Finish for Days –
This is self explanatory. A good finish goes nearly forever. A sure sign of good extraction.

Coffee Extraction Tastes  So thats the good, the bad, and the ugly of extraction and flavour. Hopefully now you will notice a few of these flavours in your day to day coffee tasting, and be able to link them with the appropriate level of extraction.

Next week, I’ll be covering the two main factors involved in changing extraction!
What flavours do you associate with ideal, under, or over-extracted coffee? Have you found a good way of communicating those flavours to others? Let me know in the comments!

 

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Pickmybrewer
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Pickmybrewer

Great post!

Amy
Guest
Amy

This has been very useful and insightful. I appreciate the distinct lack of wanking on – thank you!

Rose Martine
Guest
Rose Martine

Wonderful post! We are linking to this great article on our site. Keep up the great writing.

Matt donald
Guest
Matt donald

Love your informative article, thanks for sharing such an informative article on coffee,
thank you for sharing such a nice article, it was worth reading, will recommend others.

John Lee
Guest
John Lee

For hot coffee, what should be the temperature?

BHLearn
BHLearn

For tasting or brewing John? Studies show that there is a risk of scalding your mouth if you taste an beverage above 71°C.

mukayisenga grace
Guest
mukayisenga grace

Intresting tip

Peace
Guest
Peace

I love this description, the right extraction gives the final value to coffee before I take .

saritt staff
Guest
saritt staff

I honestly didn’t bother much about how to prepare or roast coffee. True, I was looking for information about the best espresso beans for a long time and just recently I was able to find excellent espresso coffee beans and all thanks to the article MyFriendsCoffee https://myfriendscoffee.com/best-espresso-beans/ so now I have no questions at all about coffee .

smart coffee
Guest
smart coffee

Nice blog. Good work.

adrianhasleyy
Member
adrianhasleyy

Hello! I’m currently confused as i sifted my grinds to 400-800, used 95 degree water with the ratio of 16.5:1, but it taste very dry, like very dry. Im not sure if its the TDS or the average extraction. Will it work if i increase the ratio to say 17:1? i use a melodrip and pour 30g pulses. Or is it better if i reduce the amount of pours? the aroma is really good but the taste feels way too complex and less acidity.

Arvin Tan
Guest
Arvin Tan

If your coffee tastes dry still and you still have a good aroma, I’d say to keep things simple, adjust your grind size coarser. You might be over-extracting, however, if things still do not progress for the better, i would say lower your dose.

trackback
Why Does Coffee Taste Sour?

[…] “Extraction is everything that the water takes from the coffee.” – Barista Hustle […]

Gord
Guest
Gord

I think I found what I was looking for, my coffee tastes hollow and empty, good beans but no flavor, I’m brewing according to the instructions with a French Press, temperature 205 fahrenheit brew for three and a half minutes, nothing that pleases me, I’ll keep trying until I get the desired sweetness.

Ucky
Guest
Ucky

That seems like a really long extraction time for French press.

kilgoretrout321
Member
kilgoretrout321

The standard is 4 minutes, no? And there are popular vids where extraction reaches 7 minutes or so.

jordan cunningham
Guest
jordan cunningham

How are you grinding your beans? Cheap blade grinders for example, smash coffee and create uneven particle sizes that make clear flavours almost impossible to attain. Perhaps you know this, but grind size and quality are essential to nail down for good flavour.

Ulfhedinn
Guest
Ulfhedinn

If it is too watery, you’re not even letting your coffee extract. Make sure about your grind size and try different grid sizes. also check how much your coffee interacts the water. After pouring, Stir it once or twice (again if it’s watery)

trackback
KitchenAid KES2102er Pro Line Espresso Machine Review 2019

[…] Coffee Extraction and How to Taste It. Barista Hustle. […]

trackback
Keurig K575 Review: Is It the Ultimate K-Cup Machine or Your Average Coffee Maker? - Coffee Geek Lab

[…] This feature can help you prevent the over-extraction of the coffee grounds, which often results in that unpleasant drying flavor. […]

james
Guest
james

Working on a training manual for our baristas, and this read was so helpful in learning how to clearly explain extraction. Mad props Matt, thank you!

Neil Moonshine
Guest
Neil Moonshine

What a wonderful read! Thank you for this Matt…look forward to the next Hustle. Keep up the good work!

Matt Perger
Guest
Matt Perger

Sounds.. ideal 😉

Matt Perger
Guest
Matt Perger

Thanks Neil!

Matt Perger
Guest
Matt Perger

Thanks Jack. I’m a big fan of tasting coffee at all temperatures. Different flavours seem to show themselves at different temps, like sourness upon cooling and dryness when hot. This is the same with roast faults.

Ryan Hollingshead
Guest
Ryan Hollingshead

Hi Matt, I was drinking an ideally extracted brew while I read this. Thanks for sharing your knowledge dude!

Jack O'Keefe
Guest
Jack O'Keefe

Any thoughts on tasting coffee at different temperatures to better determine extraction? I find under-extracted coffee cools sour/tart.

Fantastic read, keen for the next one.

Ryan Hollingshead
Guest
Ryan Hollingshead

Do you also both find when you extract well the coffee tends to taste great at all temperatures? I can sit with a cup for up to 30mins & enjoy every sip.

Ivan Hung
Guest
Ivan Hung

Great job, thank you.

Matt Perger
Guest
Matt Perger

Absolutely!

James Tooill
Guest
James Tooill

Thanks for writing this. I often explain and experience extraction levels as having different tactile presences and I wonder if others taste it the same way. Under-extraction feels as if the coffee were pulled too much to the front and lower sides of my palette. Leaving unbalanced sourness, and very little after taste as you said. For over-extraction I perceive that the coffee is also unbalanced in the opposite way. The coffee almost entirely misses the front and middle of my tongue and astringency quickly takes over with a high palette and back of tongue dryness in the aftertaste.

cagataygulabioglu
Guest
cagataygulabioglu

matt..like everyone else I should thank you joining the front forces of coffee elite (I am using this in a very positive way) that started to share their accumulated and scraped through knowledge, wisdom and information that is a fruit (a reference to the text) of years of hardwork.

In the context of underextraction, is there a way to differentiate the role of water quality when it comes to saltiness for instance. Or again when water has to much bicarbonate which causes high alkalinity, you can taste that stuff you call dryness; and almost chalkiness.

Gerben
Guest
Gerben

For me, this was kinda old news 😉 but I like the way you put it on paper. Well done. I believe these are the standards that any barista should know. Great starting point, can’t wait for the next Hustle 😉 G

Matt Perger
Guest
Matt Perger

My pleasure. I like using location as well, as I imagine my palate in 3 dimensions when tasting things. Unfortunately I find that everyone has slightly different spatial perception of their palate. I also enjoy using colours but that has an even lower success rate!

Matt Perger
Guest
Matt Perger

Thanks! Excellent pun.

Unless you’re using evian or san pellegrino to brew the coffee, I don’t think you’d ever experience saltiness to that degree. A salty underextracted espresso can be nigh on vegemite, whereas a slightly salty water might just display a subtle ‘mineral water’ character.

Inna Kaempf Kim
Guest
Inna Kaempf Kim

thank you for easy explanation Matt! : ) look forward to get next one.

Maxwell Mooney
Guest
Maxwell Mooney

Not to derail the discussion into other areas, but I’ve noticed that saltiness can often be a result of over-concentration, because salt has a concentration/taste threshold. If you look at many bottled waters, they contain some measure of salt, but it is undetectable because its concentration is so low. When training baristas and we encounter saltiness, a quick and simple test I have them do is to add water to the espresso and see if that reduces the saltiness. If it does, then we adjust grind to allow for the same extraction rates, but faster flow so that we can… Read more »

Danny Lewis
Guest
Danny Lewis

This was a great read, it’s good to see someone who can put all these things I’m tasting and feeling into actual usable words and vocabulary. The easier we can explain this to others in coffee and customers, the more approachable it is – which really is the goal.

Al
Guest
Al

I do get the salty thing. I wonder if salty can be the the result of not having proper temperature for espresso rather than pulling the shot too short? Too cold for example? That would give you an under extracted shot as well right?

hooshd
Guest
hooshd

Thanks Matt… this is a great summary. I’ve been reading your other pieces (and other stuff around the ‘net) about what makes a grinder’s uniform particle size distribution so important in extraction, and this helps put language around it how it affects flavour. Basically learning that a narrow, tall distribution means minimal fines and large chunks, which means it’s easier to accentuate the ‘ideal’ part of extraction (assuming you’ve got the dosing right). C.f. a non-uniform distribution where you’ll always have elements of under- and over-extraction, not optimising for ‘ideal’. Thanks for sharing – it’s all coming into focus!

Dean Mercer
Guest
Dean Mercer

Great educational read, Matt. The palate & instinct still seem to be our best guide to taste – no matter how much tech gets brought into the world of specialty coffee!

What’s your thoughts on development of grinders in further enhancing the ‘good’ elements in espresso? (RE EKG vs Mazzer etc)

Matt Perger
Guest
Matt Perger

Underextraction and high strengths go hand in hand when brewing espresso. That’s because the less water you pass through the grinds, the lower your extraction will be. So salty espresso is almost always strong as well! This is a super handy double-whammy of taste and tactile which makes identifying salty espresso easy, and as you rightly suggest, fixable with some dilution.

Aston Utan
Guest
Aston Utan

#Hustler

Matt Perger
Guest
Matt Perger

Thanks Danny. Approachable is on the top of my list!

Corey Autobee
Guest
Corey Autobee

Matt,

What’s the most you’ve extracted with a filter brew and/or espresso that still tastes great?

I’ve been experimenting with some filter brews at 27% strength lately and the results are surprising and curious!

Ruth Hampson
Guest
Ruth Hampson

Great piece, love the little graphic chart, a simple check. A must-read for all baristas.

two way petting zoo
Guest
two way petting zoo

Over-extracted filter coffee has a weird metallically mouthfeel, and under-extracted leaves something to be desired (poor finish).
With espresso, terribly under-extracted shots just feel flat and tasteless. I have achieved consistently well extracted shots with the EK43, but have great shots dialed in on Roburs as well.

two way petting zoo
Guest
two way petting zoo

This was great

Guest
Guest
Guest

Very well done, thank you! I think for baristas starting out it’s very difficult to define the difference between under and overextraction, and this was much more tactile and extremely understandable way of putting it.

I think it would might also be helpful to identify some indicators of roast faults, which can be really frustrating for baristas. For those of us not terribly familiar with the roasting process, it can be a little harder to differentiate between something that’s underextracted versus underdeveloped, for example.

Matt Perger
Guest
Matt Perger

The most I’ve ever seen for espresso was 25 but that was with an industrial grinder at the mahlkonig factory. It was awesome, but totally impractical. 27% is massive – your coffee must either be superbly developed or super dark… or you’re brewing in a blender??

Jonathan Dail
Guest
Jonathan Dail

So I completely agree with everything youve said in this write up. And I’m not too sure if someone already posted a comment about this, but I believe that we have way to quantify, scientifically, what under extraction is, low TDS or extraction less than 18%, give or take, but what would you say would be a scientific way to quantify over extraction? Especially in espresso, using a mahlkonig or mazzer youre most likely struggling to extract espresso at 20% but at the same time can have something that tastes over-extracted. So, how do (should) we define under extraction in… Read more »

Matt Perger
Guest
Matt Perger

My pleasure! In about 4 weeks you’re going to be overloaded with much much more extraction evenness and how it works – be ready!

Matt Perger
Guest
Matt Perger

Thanks Dean. I think there’s a lot of room for grinders to get better, but also for espresso to move forward with them. Espresso and grinders are kind of fighting right now and I’d love to see them act less like siblings and more like lovers. Long term project 😉

Corey Autobee
Guest
Corey Autobee

A blender may very well be the future! 🙂

Flat burrs, Kalita 155, gentle pouring, 4 min brews, VERY soluble coffee, but in no way dark…

Fruit complexities and sugars at 27% are crazy, flavors like straight up juice and herbal tea stuff… Definitely a drying sensation on the finish akin to a Yunnan or Assam tea.

Not sure how much a drying sensation bothers me if the flavors I’m getting are spectacular, ya know? I feel like if the expectation to have a dry finish, the other flavors and nuances extracted might just be worth it!

How to taste a good extraction
Guest
How to taste a good extraction

[…] Hi There, I just read this great article by Matt Perger (Champion Barista) on what to look for in an under extracted, perfectly extracted and over extracted shot. Really well written, with good examples. It looks like it's going to be the first of many posts, I've just subscribed to his e-mails to get updates. Could be a great resource for coffee fans! Coffee Extraction and How to Taste It – Matt Perger […]

james
Guest
james

Very interesting, thank you for sharing. If you have a minute or two have a look at Presto Coffee Beans.

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