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Dessert

Boiled Icing

A boiled sugar icing made with sugar, water, egg whites, lemon juice, and vanilla.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
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Why it works: Sugar and vanilla are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 35,032 recipes. Both carry beta-damascenone, which smells apple, rose. The science ↓

Boiled Icing

Ingredients

Directions

Make the syrup

  1. In a saucepan, combine 3 cups of sugar and 1 cup of water.

  2. Boil until it reaches a thick syrup consistency.

Make the icing

  1. Pour the hot syrup over the 3 egg whites while stirring vigorously.

  2. Add the juice of 1 lemon and a splash of vanilla extract.

  3. Spread the icing on the cake while it is still warm.

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 + vanillatop 8% of all pairs
    Smell alikelow
    Cooked together35,032 recipes

    Shared aroma: beta-damascenone (apple, rose).

  2. Lemon + vanillatop 15% of all pairs
    Smell alikemoderate
    Cooked together5,961 recipes

    Shared aroma: eucalyptol (eucalyptus, herbal).

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

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

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

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

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

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

Sugar and vanilla barely smell alike, yet cooks put them together in 35,032 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

Sugar
Dissolves into the water to form a syrup that sets into a sweet, glossy icing.
Egg whites
Whipped by the hot syrup into a foam that gives the icing its light, airy structure.
Lemon juice
Adds acidity that balances the sweetness and helps keep the icing stable.

The step that matters

Pouring the hot syrup over the egg whites while stirring vigorously. The hot syrup cooks the egg white proteins as it is beaten in, creating a stable foam. If the syrup is poured too slowly or the stirring stops, the whites can partly cook into lumps or the foam can collapse.

Swap the lemon

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

  1. Figfits better
  2. Blueberryfits better
  3. Peachfits better
  4. Lemonthe original

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