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Dessert

Royal Icing

A sweet glaze made from icing sugar, egg white, 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

Make the icing

  1. Sift the icing sugar into a bowl.

  2. Add the egg white and mix well.

  3. Gradually add lemon juice until a soft paste forms.

  4. Beat the mixture until it is white and very light.

  5. Color part of the icing with a few drops of food coloring if desired.

Ice the cake

  1. Dust off any loose crumbs from the cake.

  2. Apply bits of icing all over the sides of the cake and smooth with a knife.

  3. Dip the knife in cold water and lightly smooth the surface.

  4. Ice the top of the cake in the same manner.

  5. Use forcing tubes to decorate as desired.

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
Forms the bulk of the icing and sets firm as it dries, giving structure.
Egg white
Adds body and helps the icing whip up light and hold its shape.
Lemon juice
Thins the sugar into a spreadable paste and adds a slight tang.

The step that matters

Beat the mixture until it is white and very light. Beating incorporates air into the egg white and sugar, which makes the icing lighter and easier to spread. Under-beaten icing stays dense and may not set into a smooth, firm finish.

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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