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 Filling
Ingredients
Directions
Make the filling
Mix sugar and flour, add grated lemon rind, lemon juice, and slightly beaten egg.
Put butter in a saucepan; when melted, add the mixture.
Stir constantly until the mixture reaches boiling point.
Ensure the mixture does not stick to the bottom of the saucepan.
Cool and use
Cool the filling before spreading it into a pie or pastry.
Nutrition, whole recipe (rough)
What these numbers assume: 5 portions
| Ingredient | Portion assumed | kcal |
|---|---|---|
| Flour | 1 cup (125g) all-purpose | 455 |
| Butter | 1 tbsp (14g) | 102 |
| Egg | 1 large egg (50g) | 78 |
| Sugar | 1 tbsp (12.5g) granulated | 49 |
| Lemon | juice of 1 lemon (48ml) | 12 |
One typical portion per ingredient; the recipe's quantities are not counted. A rough guide only, not for medical or dietary planning.
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. See the original page.
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.
-
Flour + buttertop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
-
Flour + eggtop 15% of all pairsSmell alikelowCooked together106,462 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Lemon + buttertop 16% of all pairsSmell alikemoderateCooked together41,227 recipes
Shared aroma: 3-hexenal (apple, fruity).
-
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
- Egg
- Thickens the filling as it heats and gives it a rich, set texture.
- Flour
- Thickens the filling by absorbing liquid and helping it set when heated.
- Sugar
- Sweetens the filling and balances the sharpness of the lemon.
- 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
Stirring until boiling, without scorching. The egg and flour thicken only when the mixture heats enough, but the egg can curdle and the bottom can scorch if heat is too high or stirring stops. Constant stirring spreads heat evenly and keeps the filling smooth and set.
Swap the lemon
How well each one fits the dish's main ingredients (sugar, flour, egg, butter):
- Raisinfits better
- Vanillafits better
- Figfits about as well
- Lemonthe original
Fit is the average pairing score against sugar, flour, egg, butter. 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.
More lemon filling recipes
You might also like
Lemon Cake228 recipes
Lemon Ice147 recipes
Lemon Sherbet103 recipes
Lemon Custard64 recipesThe free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.