Name: Lemon Syrup
Ingredients: 2 lbs loaf sugar; 1 oz citric acid; ⅓ teaspoon essence of lemon; 2 pints water

Why it works: Sugar and lemon are a kitchen classic. They rank in the top 18% of all ingredient pairs, and cooks put them together in 53,532 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓

Lemon Syrup

Ingredients

2 lbs loaf sugar
1 oz citric acid
⅓ teaspoon essence of lemon
2 pints water

Directions

Make the syrup

Boil the sugar in the water for 15 minutes.
Pour the mixture into a basin and let it cool.

Flavour and bottle

Pound the citric acid and mix it with the essence of lemon.
Add the mixture to the syrup and bottle for use.

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.

Sugar + lemontop 18% of all pairs

Smell alikelow

Cooked together53,532 recipes

Shared aroma: 2-nonenal (fatty, green).

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

Loaf sugar: Dissolves in boiling water to form the sweet body of the syrup.
Citric acid: Adds sharp acidity that brightens the lemon flavour and balances the sweetness.
Essence of lemon: Provides concentrated lemon aroma that carries the flavour of the syrup.

“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.