Bitterness (coffee)
Flavour perceived at the back of the tongue, linked to caffeine, trigonelline, degraded chlorogenic acids and Maillard compounds. A defect if dominant, a quality if integrated. Clean bitterness (well-extracted espresso) differs from harsh bitterness (burnt, over-extracted). Intensified by dark roasting and over-extraction.
Why does bitterness matter for a coffee's balance?
Bitterness in coffee is one of the most misunderstood and feared attributes, yet it is an essential part of the cup. Pure bitterness is detected by taste receptors on the back of the tongue and is triggered by a range of compounds produced during roasting: melanoidins (high-molecular-weight browning compounds, formed through the Maillard reaction), phenylindanes (produced from chlorogenic acid degradation above 200°C), and caffeine itself (though caffeine contributes only 10-15% of perceived coffee bitterness). Counter-intuitively, darker roasts are not necessarily more bitter in a negative sense: at very high temperatures, some bitter compounds break down further into other compounds, while chlorogenic acids (which generate harsh, astringent bitterness) are largely degraded. The bitterness of over-extraction (running espresso too long, steeping filter coffee too long) produces a different, harsher quality (phenylindane-dominated) that is unpleasant and avoidable. In a well-extracted specialty coffee, a pleasant bitter note in the background provides structure and depth, similar to how tannins function in red wine. The SCA cupping protocol does not score bitterness directly; it is captured indirectly through the 'flavour', 'aftertaste', and 'balance' attributes.
How do you control bitterness in the cup?
If your coffee tastes unpleasantly bitter, first check extraction: is the brew too dark, the grind too fine, or the contact time too long? A French press left steeping for 10 minutes will taste significantly more bitter than at 4 minutes. For espresso, a shot running over 35 seconds at 9 bars begins extracting phenylindane-dominated bitter fractions. To calibrate your palate for the difference between pleasant structure and unpleasant bitterness, try adding a small pinch of salt to a mildly bitter coffee, salt suppresses bitter receptors and can help isolate the underlying flavour.
Related Terms
Related terms: Over-extraction, the most common cause of harsh bitterness. Maillard reaction, produces melanoidins, a key bitter compound. Caffeine, contributes ~10-15% of perceived bitterness. Dark roast, higher melanoidin content, more bitter structure.