Name: Barley Water
Ingredients: 1 pint boiling water; 2 oz pearl barley; 1 tablespoon sugar; peel from ¼ lemon

Why it works: Barley and lemon work together. They rank in the top 13% of all ingredient pairs, and cooks put them together in 484 recipes. Both carry 3-hexenal, which smells apple, fruity. The science ↓

Barley Water

Ingredients

1 pint boiling water
2 oz pearl barley
1 tablespoon sugar
peel from ¼ lemon

Directions

Prepare

Wash the barley well in two or three waters.

Make the barley water

Put the barley, sugar, and thinly cut lemon peel into a pitcher.
Pour 1 pint of boiling water over the mixture.
Cover the pitcher and let it stand on ice until cold.
When cold, strain into another pitcher.

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.

Barley + lemontop 13% of all pairs

Smell alikemoderate

Cooked together484 recipes

Shared aroma: 3-hexenal (apple, fruity).
Sugar + lemontop 18% of all pairs

Smell alikelow

Cooked together53,532 recipes

Shared aroma: 2-nonenal (fatty, green).
Barley + sugartop 21% of all pairs

Smell alikemoderate

Cooked together755 recipes

Shared aroma: beta-damascenone (apple, rose).

Sugar and lemon barely smell alike, yet cooks put them together in 53,532 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

Pearl barley: Its starch releases into the water, giving the drink its body and thickness.
Sugar: Adds sweetness that balances the tart lemon peel.
Lemon peel: Its oils add aroma and a light citrus flavour to the water.