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Rock, or Souffle Sugar

A sugar confection made by boiling sugar to crack stage, adding egg white and lemon juice, and caramelizing the top.

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 ↓

Rock, or Souffle Sugar

Ingredients

Directions

Make the sugar mixture

  1. Boil the sugar until it reaches the crack stage.

  2. Add the egg white and lemon juice, stirring quickly.

  3. Allow the mixture to rise in the pan, then stir again to deflate.

  4. Continue working the mixture until it rises again.

Set and finish

  1. Pour the mixture into the prepared paper case, which has been dredged with fine sifted sugar.

  2. Hold a red-hot shovel over the soufflé for two minutes to caramelize the top.

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

Loaf sugar
Forms the crystalline sugar structure that sets into a crisp, brittle candy.
Egg white
Traps air as it is whipped into the syrup, making the mixture rise and turn light.
Lemon juice
Adds acidity that helps keep the sugar smooth and stabilizes the foam.

The step that matters

Stirring the mixture as it rises and deflating it. Sugar syrup cooled to the crack stage sets quickly, so the mixture must be worked while it is still fluid. Stirring to deflate and then letting it rise again keeps the foam light and airy, and pouring too late leaves it dense.

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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