Under-extraction

A shot or brew where not enough has been extracted — the cup tastes sour, sharp, watery, or thin. Typically extraction yield below 18% for espresso.

Why it matters — Under-extraction is the most common fault for beginners. The cup is dominated by acidic and sour compounds that come out early in extraction, without the balance of the sweeter, fuller-bodied compounds that come out later.

Good to know

• Fix by grinding finer, increasing dose, raising temperature, or extending the shot/brew time.
• Common symptoms: shot runs too fast, no crema, thin mouthfeel, watery body, sharp citric acidity.