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Dessert

Lemon Filling

A lemon custard made by cooking sugar, flour, egg, butter, lemon rind, and lemon juice until boiling.

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

  1. In a bowl, mix sugar, flour, egg, butter, lemon rind, and lemon juice in the order given.

  2. Cook the mixture in a saucepan over medium heat, stirring constantly until it reaches a boiling point.

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. Butter + lemontop 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

Egg
Thickens the custard as its proteins set during gentle cooking, giving it body.
Flour
Thickens the custard by absorbing liquid and swelling when heated, giving it structure.
Sugar
Adds sweetness and helps balance the sharpness of the lemon juice.
Lemon juice
Adds acidity and bright lemon flavour that defines the custard.

The step that matters

Cooking the mixture to a boil while stirring constantly. Flour needs to reach a boil to fully swell and thicken, and constant stirring prevents lumps and scorching on the bottom of the pan. Egg proteins can curdle if the heat is too intense, so medium heat helps keep the custard smooth.

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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