Name: Lemon Syrup
Ingredients: 6 lemons; 2 oz tartaric acid; 3 lbs lump sugar; 2 quarts boiling water

Why it works: Lemon and sugar 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

6 lemons
2 oz tartaric acid
3 lbs lump sugar
2 quarts boiling water

Directions

Prepare the lemons

Peel the yellow rind off the lemons with a knife.
Remove the white rind with your fingers and discard it.
Slice the lemons thinly and place them in a vessel with the peel.
Crush the lemons with a potato masher.

Steep and bottle

Add the tartaric acid, lump sugar, and boiling water.
Stir occasionally and let the mixture stand overnight.
Strain the mixture and bottle it 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.

Lemon + sugartop 18% of all pairs

Smell alikelow

Cooked together53,532 recipes

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

Lemon and sugar 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

Lemons: Supply the juice and aromatic oils that give the syrup its flavour and tartness.
Tartaric acid: Adds sourness that balances the sweetness of the sugar.
Lump sugar: Sweetens the syrup and helps preserve it once bottled.

“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.