Why it works: Butter and flour 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 says “a slow oven”. The 300°F (150°C) in the steps is the modern equivalent, not the book's own figure.
Make the filling
Dissolve the flour in a little cold water.
Stir the dissolved flour into the boiling water, then add the butter and sugar.
Cook until clear, being careful not to scorch.
Remove from heat and add the well-beaten yolks of the eggs and lemon juice.
Pour the mixture into pre-baked pie shells.
Top and bake
Whip the egg whites until stiff, then add 2 teaspoons of sugar and a few drops of lemon juice.
Spread the whipped egg whites on top of the pie and brown in a 300°F (150°C) oven.
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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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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Egg + flourtop 15% of all pairsSmell alikelowCooked together106,462 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Butter + lemontop 16% of all pairsSmell alikemoderateCooked together41,227 recipes
Shared aroma: 3-hexenal (apple, fruity).
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Lemon + flourtop 17% of all pairsSmell alikemoderateCooked together30,404 recipes
Shared aroma: isobutyraldehyde (malty, green).
Butter and flour 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
- Eggs
- Yolks thicken the filling, and whipped whites form the light, browned topping.
- Sugar
- Sweetens the filling and helps stabilise the whipped egg white topping.
- Flour
- Cooked with boiling water, it thickens the filling into a smooth custard.
- Lemon
- Juice and rind provide the sharp, fragrant citrus flavour.
The step that matters
Cook until clear, without scorching. The starch in the flour mixture must be fully cooked to thicken the filling properly. Heating too fast or too long can scorch the bottom of the pan and give a burnt taste, while undercooking leaves the filling thin.
Swap the lemon
How well each one fits the dish's main ingredients (sugar, butter, egg, flour):
- Raisinfits better
- Vanillafits better
- Figfits about as well
- Lemonthe original
Fit is the average pairing score against sugar, butter, egg, flour. 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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