How Sauces Thicken: The Science

Making Thin Sauces Rich and Thick

1. Starch (The Basic Method)

Starch swells with heat and water, creating thickness.

Starch types:

Starch	Clarity	Best For
Potato	Clear	Asian stir-fries
Cornstarch	Semi-clear	Western sauces, gravy
Tapioca	Very clear	Glossy Asian sauces

Mix starch with cold water first (slurry), then add to hot sauce while stirring.

2. Roux (Flour + Butter)

Western cooking staple:

• White roux (1-2 min): Béchamel, cream soups
• Blonde roux (3-5 min): Velouté
• Brown roux (10-15 min): Espagnole, gumbo

Longer cooking = deeper flavor but less thickening power.

3. Reduction

Simply boil the sauce to evaporate water. Concentrates flavor naturally.

4. Egg Yolks

For cream sauces — temper first (slowly add hot sauce to yolks) to prevent scrambling.

5. Butter Finish (Monter au beurre)

Swirl cold butter into sauce off heat for glossy, creamy texture.

Tip: Don't over-thicken — sauces get thicker as they cool!