Why it works: Flour and sugar are a kitchen classic. They rank in the top 15% of all ingredient pairs, and cooks put them together in 92,116 recipes. Both carry phenylacetaldehyde, which smells hawthorne, honey. The science ↓
Lemon Pie
Ingredients
Directions
Make the filling
Grate the rind of the lemon and squeeze the juice.
In a saucepan, combine the lemon juice, grated rind, flour, sugar, and water.
Boil the mixture until it thickens.
Pour the filling into a baked pie crust.
Top and bake
Bake until light brown.
Whip the egg whites with sugar until frothy.
Spread the whipped egg whites over the pie.
Return the pie to the oven to brown the topping.
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.
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Flour + sugartop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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Flour + eggtop 15% of all pairsSmell alikelowCooked together106,462 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Lemon + flourtop 17% of all pairsSmell alikemoderateCooked together30,404 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Lemon + sugartop 18% of all pairsSmell alikelowCooked together53,532 recipes
Shared aroma: 2-nonenal (fatty, green).
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Lemon + eggtop 19% of all pairsSmell alikelowCooked together44,316 recipes
Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).
Flour and egg barely smell alike, yet cooks put them together in 106,462 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
- Flour
- Thickens the lemon filling so it sets into a sliceable custard.
- Egg whites
- Whipped with sugar to form a foam that becomes the browned topping.
- Egg yolks
- Enrich and thicken the filling, adding richness and a smooth texture.
- Sugar
- Sweetens the filling and helps stabilise the whipped egg white topping.
- Lemon
- Provides the acidity and aroma that flavour the filling.
The step that matters
Boil the filling until it thickens. Flour starch only thickens fully when the mixture reaches a boil, and it must be cooked long enough to gel. Undercooked filling stays runny and will not hold a clean slice after cooling.
Swap the lemon
How well each one fits the dish's main ingredients (flour, sugar, egg):
- Raisinfits better
- Vanillafits better
- Lemonthe original
- Figfits about as well
Fit is the average pairing score against flour, sugar, egg. Candidates are from the same food group and used in at least 100 recipes.
“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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