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Dessert

Rock Sugar

A candy made by clarifying sugar, mixing egg‑white icing, boiling sugar to crack stage, and adding the icing to form a crystalized syrup.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 4 ingredients
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Why it works: Sugar and egg are a kitchen classic. They rank in the top 21% of all ingredient pairs, and cooks put them together in 122,807 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓

Rock Sugar

Ingredients

Directions

Prepare

  1. Clarify the loaf sugar.

  2. Separate the egg whites from the yolks and place the whites in a pan.

  3. Sift loaf sugar into the egg whites to make Royal Icing and mix thoroughly.

  4. Pour the icing into small pots and add food coloring.

Make the rock sugar

  1. In a separate pan, add fresh sugar to the clarified sugar and boil until it reaches the 'crack' stage.

  2. Remove from heat, dip a spoon into the Royal Icing, and add it to the syrup.

  3. Mix briskly for a few minutes until the syrup rises, then stop stirring.

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

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

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Egg whites
Whip-free binder in the Royal Icing, giving it body and helping it hold its shape.
Loaf sugar
Forms the base sugar that is clarified and dissolved into the syrup for the crystals.
Fresh sugar
Adds to the clarified sugar in the pan and is boiled to the crack stage to build the syrup.

The step that matters

Mixing the Royal Icing into the syrup. Adding the icing and then stopping stirring lets the syrup rise and form crystal nuclei. Stirring too long or too late can disturb crystal growth and produce uneven or cloudy rock sugar.

“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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