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Dessert

Royal Icing

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

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

Prepare the sugar

  1. Sift the icing sugar through a fine sieve into a bowl.

Make the paste

  1. Make a well in the center and add the slightly beaten egg whites.

  2. Stir in a little of the icing sugar.

  3. Add about half the lemon juice and mix into a moist paste, using more lemon juice as needed.

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. Lemon + eggtop 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 the bulk and sweetness that makes up most of the icing.
Egg whites
Add protein structure that holds the icing together and dries to a firm finish.
Lemon juice
Adds acidity and liquid to loosen the sugar into a spreadable paste.

The step that matters

Adding the lemon juice. Icing sugar absorbs liquid gradually, so adding the lemon juice in small amounts keeps the paste thick enough to hold its shape. Too much liquid at once makes the icing runny and slow to set.

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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