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.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.

1. 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.

i always define sourness as being negative. a sour flavour hits you quickly and aggressively. ıt 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. ıt’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.

2. 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 gail : something that’s really difficult to find and stupendously rewarding once you get it. under-extraction isn't sweet. 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.

3. salty
under-extracted coffee is salty.  under-extracted coffee almost always has 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. 

4. 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.

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. ıt's an abrupt and unsatisfying end to your coffee experience.

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.