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Dessert

Boiled Icing

A sugar icing made by boiling sugar, cooling, and folding into beaten egg whites, flavored with lemon or vanilla.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 4 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 ↓

Boiled Icing

Ingredients

Directions

Make the syrup

  1. Pour enough boiling water over the sugar to melt it.

  2. Boil the sugar until it threads when lifted with a spoon.

  3. Let the sugar syrup cool slightly.

Whip and finish

  1. Beat the egg whites to a stiff froth.

  2. Pour the cooled syrup over the beaten egg whites.

  3. Beat until thoroughly mixed and stiff enough to spread over the cake while warm.

  4. Flavor with lemon or vanilla extract.

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

Granulated sugar
Dissolves into the syrup that sets the icing's sweetness and body.
Egg whites
Beaten to a stiff froth, they trap air and give the icing its light, fluffy structure.

The step that matters

Boil the sugar until it threads. Sugar syrup must reach the right concentration to set properly. Too little cooking leaves the icing runny, while overcooking makes it hard and grainy as it cools.

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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