Name: Roux, White and Brown, to Keep
Ingredients: ¼ pound butter; ¼ pound flour; 2 tablespoons white roux; ½ pint milk

Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓

Roux, White and Brown, to Keep

Ingredients

¼ pound butter
¼ pound flour
2 tablespoons white roux
½ pint milk

Directions

Make the roux

Cook the butter and flour together in a saucepan over medium heat until they bubble, about 1-2 minutes. Do not allow the mixture to brown.
Remove from heat, transfer the roux to a small jar, cover, and store in a cool place.

Make the sauce

Melt 2 tablespoons of the white roux in a saucepan.
Add ½ pint of milk and cook until smooth.
Season to taste.

Recipe from a historical cookbook (Internet Archive).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

Butter + milktop 7% of all pairs

Smell alikemoderate

Cooked together81,283 recipes

Shared aroma: (z)-4-heptenal (biscuit, cream).
Butter + flourtop 12% of all pairs

Smell alikelow

Cooked together124,287 recipes

Shared aroma: isobutyraldehyde (malty, green).
Flour + milktop 14% of all pairs

Smell alikelow

Cooked together78,219 recipes

Shared aroma: isobutyraldehyde (malty, green).

Butter and flour barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Butter: Fat that coats the flour so it blends smoothly and carries flavour into the roux.
Flour: Starch that swells when heated with fat and milk, thickening the sauce.
White roux: Ready-made butter and flour mixture that thickens the sauce when melted into milk.
Milk: Liquid that the starch thickens into a smooth, creamy sauce.

The step that matters

Cook the roux without browning it. Cooking the butter and flour until they bubble drives off raw flour taste and lets the starch begin to thicken. Browning changes the colour and flavour and weakens the roux's thickening power, so keep it pale and stop once it bubbles.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.

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Roux, White and Brown, to Keep