Brewing and Barista Techniques
Core concepts
Every brew is a balance of four levers: dose (dry coffee mass), grind size, water temperature, and brew ratio (coffee to water). Extraction moves solubles from grounds into water; under-extraction tastes sour, thin, and salty, while over-extraction tastes bitter, dry, and hollow. Espresso adds pressure and time as variables, so a barista dials in by holding dose and yield constant and adjusting grind first.
Know the standard reference points: espresso is typically brewed near 9 bar with water around 90-96°C, a normal espresso ratio is roughly 1:2 (dose to liquid yield), and a typical extraction window is 25-30 seconds. Filter methods (pour-over, immersion) use coarser grinds and longer contact times. Puck preparation - level distribution and consistent tamp pressure - matters because channeling lets water bypass coffee, producing both sour and bitter notes at once.
Traps in questions
- Confusing strength (TDS, concentration) with extraction (percentage of solubles removed). A strong but under-extracted shot is possible.
- Assuming finer grind always means "better." Finer increases resistance and extraction, but too fine causes channeling and slow, bitter shots.
- Forgetting that increasing dose at fixed yield reduces extraction percentage, not increases it.
- Milk texturing questions: microfoam is created by introducing air early, then submerging the tip to incorporate; overheating scalds proteins and kills sweetness.
Worked example
A shot runs 18 g in, 36 g out in 20 seconds and tastes sour. Rule of thumb: sour and fast = under-extracted, so tighten the grind slightly (finer) and re-test, keeping dose and yield fixed. Change one variable at a time.