Why it works: Flour and butter are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 124,287 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓
Lemon Pie
Ingredients
Directions
The book gives no oven temperature. The 350°F (175°C) in the steps was added when the recipe was transcribed, as a starting point.
Make the filling
Mix the sugar and flour together in a bowl.
Add the boiling water and cook for about 5 minutes, stirring frequently.
Beat the egg yolks in a separate bowl.
Add the cooked mixture to the beaten egg yolks and stir in the butter.
Cook until the mixture thickens, then remove from heat.
Stir in the lemon juice and grated lemon rind.
Once cooled slightly, pour the mixture into a baked pie crust.
Top and bake
Beat the egg whites until stiff, then gradually add the icing sugar.
Spread the meringue over the pie and bake at 350°F (175°C) until golden brown.
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 + buttertop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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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 + buttertop 16% of all pairsSmell alikemoderateCooked together41,227 recipes
Shared aroma: 3-hexenal (apple, fruity).
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Flour + lemontop 17% of all pairsSmell alikemoderateCooked together30,404 recipes
Shared aroma: isobutyraldehyde (malty, green).
Flour and butter 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
- Flour
- Thickens the filling as it cooks, giving it a set, sliceable body.
- Egg yolks
- Enrich and thicken the filling, adding richness and a smooth custard texture.
- Egg whites
- Whipped into the meringue, giving the topping its airy structure and browning.
- Lemon juice
- Adds acidity that gives the filling its sharp, bright lemon flavour.
- Butter
- Adds fat and richness to the cooked filling, smoothing its flavour and texture.
- Sugar
- Sweetens the filling and helps stabilise the cooked mixture.
The step that matters
Cook until the mixture thickens. Flour thickens as its starch swells in hot liquid. Stop too early and the filling stays runny; the egg yolks also need to be heated gently with the starch, not boiled hard, so they set smoothly without curdling.
Swap the lemon
How well each one fits the dish's main ingredients (flour, sugar, butter, egg):
- Raisinfits better
- Vanillafits better
- Figfits about as well
- Lemonthe original
Fit is the average pairing score against flour, sugar, butter, 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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