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Dessert

Lemon Filling

A sweet lemon custard used as a filling for pies or pastries.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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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

Prepare

  1. Mix sugar and flour in a bowl.

  2. Add grated lemon rind, lemon juice, and slightly beaten eggs.

  3. Melt butter in a saucepan.

Make the filling

  1. Add the mixture to the melted butter.

  2. Stir constantly until it reaches boiling point.

  3. Prevent the mixture from sticking to the bottom of the saucepan.

Finish

  1. Cool before spreading.

Recipe from a historical cookbook (Internet Archive).

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.

  1. Flour + buttertop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  2. Sugar + flourtop 15% of all pairs
    Smell alikemoderate
    Cooked together92,116 recipes

    Shared aroma: phenylacetaldehyde (hawthorne, honey).

  3. Flour + eggtop 15% of all pairs
    Smell alikelow
    Cooked together106,462 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Lemon + buttertop 16% of all pairs
    Smell alikemoderate
    Cooked together41,227 recipes

    Shared aroma: 3-hexenal (apple, fruity).

  5. Flour + lemontop 17% of all pairs
    Smell alikemoderate
    Cooked 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

Sugar
Adds sweetness that balances the sharpness of the lemon juice.
Flour
Its starch swells as the mixture heats, thickening the filling.
Eggs
Their proteins set as they heat, giving the filling body and structure.
Lemon juice
Provides the sour, bright acidity that defines the filling.
Lemon rind
Adds concentrated lemon aroma from the peel's oils.
Butter
Adds fat that makes the filling smooth and rich.

The step that matters

Stir constantly until boiling point. Constant stirring keeps the heat even, so the eggs thicken smoothly instead of scrambling. Flour starch and egg proteins set as the mixture heats, and pausing can cause lumps or scorching on the pan bottom.

Swap the lemon

How well each one fits the dish's main ingredients (sugar, flour, egg, butter):

  1. Raisinfits better
  2. Vanillafits better
  3. Figfits about as well
  4. 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.

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