over-extracted coffee

let's now cast our attention to the opposite end of extraction street.

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. 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.

1. bitter

coffee is bitter. over-extracted coffee is really bitter. unless i’m drinking campari, ı 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 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’.

2. 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. ın 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 sensation in the mouth.

3. 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. ıt’s luscious, smooth and, well, mouthfilling. over-extracted coffee is empty, hollow, rough. 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. these flavours aren’t desirable. these flavours born as a consequence of malextraction.