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 Filling
Ingredients
Directions
In a double boiler, combine water, sugar, eggs, butter, lemon rind, and lemon juice.
Cook while stirring until the mixture thickens to the consistency of thick cream.
Add flour gradually until the desired thickness is achieved.
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
- Set and thicken the custard as they cook, giving the filling body.
- Flour
- Thickens the filling further, adding body to the lemon mixture.
- Sugar
- Sweetens the filling and balances the sharpness of the lemon juice.
- Lemon juice
- Adds acidity and bright lemon flavour to the filling.
- Butter
- Adds richness and a smooth, silky mouthfeel to the filling.
The step that matters
Cook while stirring in the double boiler. Egg proteins set gently as they heat, thickening the filling. Heating too fast or without stirring can curdle the eggs or leave lumps, so the mixture should be stirred steadily over gentle heat.
Swap the lemon
How well each one fits the dish's main ingredients (sugar, egg, butter, flour):
- Raisinfits better
- Vanillafits better
- Figfits about as well
- Lemonthe original
Fit is the average pairing score against sugar, egg, butter, 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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