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Dessert

Lemon Filling

A thickened lemon custard used as a filling.

From an old cookbook · modernised transcription
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Why it works: Butter and lemon are a kitchen classic. They rank in the top 16% of all ingredient pairs, and cooks put them together in 41,227 recipes. Both carry 3-hexenal, which smells apple, fruity. The science ↓

Lemon Filling

Ingredients

Directions

  1. Mix cornstarch and sugar in a saucepan.

  2. Add boiling water and cook, stirring constantly, until thick; continue cooking for 10 minutes.

  3. Add butter and slightly beaten egg yolks; cook until the egg thickens.

  4. Remove from heat and stir in lemon juice and grated lemon rind.

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. Butter + lemontop 16% of all pairs
    Smell alikemoderate
    Cooked together41,227 recipes

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

  2. Butter + eggtop 17% of all pairs
    Smell alikemoderate
    Cooked together118,967 recipes

    Shared aroma: decanal (soap, orange peel).

  3. Sugar + buttertop 17% of all pairs
    Smell alikemoderate
    Cooked together98,233 recipes

    Shared aroma: guaiacol (smoky, sweet).

  4. Sugar + lemontop 18% of all pairs
    Smell alikelow
    Cooked together53,532 recipes

    Shared aroma: 2-nonenal (fatty, green).

  5. Egg + lemontop 19% of all pairs
    Smell alikelow
    Cooked together44,316 recipes

    Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).

Sugar and lemon barely smell alike, yet cooks put them together in 53,532 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

Cornstarch
Thickens the filling as it heats with the liquid, giving it body.
Egg yolks
Thicken the filling further as they cook and add richness.
Lemon juice
Adds acidity that brightens the sweetness of the filling.
Butter
Adds fat for a smooth, rich texture and mouthfeel.

The step that matters

Cooking the egg yolks. Egg yolks can curdle or scramble if overheated or added too quickly to hot liquid. Stirring constantly and cooking gently until the mixture thickens keeps the filling smooth.

Swap the lemon

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

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

Fit is the average pairing score against sugar, butter, egg. 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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