Lab Technique · Entry 20 of 42
Evaporation / Concentration
Driving off solvent to concentrate a solution.
How it works in the lab
Chemists concentrate solutions on a rotary evaporator, where reduced pressure lowers the boiling point so solvent boils off gently at 30 to 40 °C instead of heating the compound to destruction. The spinning flask creates a thin film that evaporates fast, and a condenser traps the solvent for recovery. Labs concentrate rather than evaporate to dryness when the product is heat sensitive, showing that how you remove solvent matters as much as how much you remove.
Research Findings
The kitchen analog of rotary evaporation.
Skills you gain in the lab and kitchen
- Reducing a liquid to a target volume
- Using low, steady heat to avoid scorching
- Increasing surface area for faster evaporation
- Judging concentration by texture and appearance
- Preventing boil-over during reduction
How it shows up in baking
Simmering apple butter or tomato sauce for hours drives off water and concentrates flavor, and a pastry chef reduces fruit juice to a glossy glaze. Gentle, wide-surface, low-heat reduction is chosen for the same reason rotavap users choose vacuum: to remove water without burning what remains. Both processes trade time and control for concentration without scorching.
Recipes that demonstrate this technique
Each card shows exactly where the technique appears inside that recipe's method.