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Dessert

Royal Icing

A smooth icing made from icing sugar, egg whites, and lemon juice.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 3 ingredients
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Why it works: Sugar and lemon are a kitchen classic. They rank in the top 18% of all ingredient pairs, and cooks put them together in 53,532 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓

Royal Icing

Ingredients

Directions

  1. Place the icing sugar in a bowl.

  2. Add the whisked egg whites and strained lemon juice.

  3. Stir until perfectly smooth.

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

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

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

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

  3. Sugar + eggtop 21% of all pairs
    Smell alikemoderate
    Cooked together122,807 recipes

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

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

Icing sugar
Provides sweetness and bulk, and its fine texture helps the icing set smooth.
Egg whites
Provide structure and body, helping the icing hold its shape as it dries.
Lemon juice
Adds acidity that balances the sweetness and helps keep the icing bright.

The step that matters

Stir until perfectly smooth. Undissolved sugar grains or lumps leave a gritty texture and can make the icing look uneven. Stirring thoroughly until no lumps remain gives a smooth finish and an even surface when the icing dries.

Swap the lemon

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

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

Fit is the average pairing score against sugar, 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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