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Sauces and finishing · beginner

Reduction

Also: reducing

Simmering or boiling a liquid uncovered to evaporate water and concentrate flavour and body.

87 recipes use it

What it is

Reduction concentrates stocks, wines, sauces, gravies and syrups by evaporating water. Recipes often say 'reduce by half' or 'until syrupy'.

Why cooks use it: Less water means stronger flavour and thicker texture from dissolved gelatin, sugars and starches, without adding thickeners.

The science

Evaporation happens at the surface, so wide pans reduce faster. Non-volatile components (salt, sugar, gelatin, acids) stay behind and concentrate; some delicate aromas evaporate with the steam.

CaramelisationEvaporation and reductionEmulsionsHow sugar behavesSalt and osmosisCrystallisation

Step by step

  1. Use a wide pan for faster evaporation.

  2. Bring the liquid to a strong simmer or gentle boil, uncovered.

  3. Skim any foam or fat that rises.

  4. Measure progress by the level in the pan or by dipping a spoon.

  5. Season only once reduced, as salt concentrates.

Heat and timing

  • Reduction 90–100 °C · Steady simmer to gentle boil.

Time: A few minutes for pan sauces; 30–60 minutes or more for stock reductions.

How you know it’s right

  • Liquid coats the back of a spoon (nappe)
  • A finger drawn through the coating leaves a clean line
  • Bubbles become larger and slower as it thickens

Common mistakes

  • Salting before reducing
  • Reducing too far so sugars burn
  • Reducing dairy too hard so it splits

Troubleshooting

Too salty after reducing
Add unsalted stock or water; season later next time.
Sticky, burnt glaze
Lower the heat as it thickens and watch closely at the end.

Restaurant DNA

How professionals do it

Restaurants reduce large batches of stock into demi-glace or glace and keep them as a concentrated base; pan sauces are made to order from that base plus the pan juices.

At home

Freeze reduced stock in ice-cube trays for quick, intense pan sauces.

General professional practice — not any particular restaurant’s recipe.

Food safety

  • Sugary reductions get very hot; do not taste from the pan.

Practise it

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