I’m often asked about bitterness in coffee. Coffee beans contain over 800 flavour components which include sweet, salty, bitter, sour and bitterness components. A bean’s inherent bitterness can be extracted if you’re not careful on how you take care of your beans and make your coffee. Too often coffee is erroneously blamed for bitterness in the cup. A simple test to determine if the bitterness is originating from your beans is to chew the bean. If you are experiencing bitterness in your coffee it may be due to:
Dark roasted beans – our beans are principally Arabica and roasted to a medium level. Dark roasts are more likely have higher levels of bitterness and this will be evidenced by dark glossy beans covered in oil which has been drawn out by the longer roast. Oils exposed to air quickly become rancid. You’ll note our beans have a matt complexion with maybe a bead of oil and no more. You won’t receive heavily roasted beans from us unless you request it.
Using water that is too hot – hot water extracts bitter compounds. Temp should be 92-94 degrees celsius. Don’t add boiling water to your plunger, wait for it to cool down a bit first.
Incorrect extraction due to wrong grind. A shot of coffee should be 25-30 seconds and no more because beyond that you will extract bitter compounds. If you want a long coffee, add hot but not boiling water from a kettle.
Impacts of using the wrong grind size:
Too fine - results in over-extraction (excessive exposure to hot water) which results in burning of the many and delicate oils in the bean. This results in bitterness and off flavours from burned oils similar to the characters of rancid oil.
Too course – results in under extraction (under exposure to hot water) which manifests as a poor whitish/light brown crema, thin and insipid coffee. The compounds in the whitish crema undermine the sweeter coffee flavours, in particular the caramelised sugars of the roast, which results in bitterness.
• Dirty equipment (coffee machine and/or grinder) – dirty equipment accumulates deposits of oils and coffee grind which become rancid and impart a bitterness. Depending on use, clean your equipment often and at least monthly. Cafes should do it daily.
• Stale coffee.