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 ↓
Frost, or Icing, for Cakes
Ingredients
Directions
The book says “a cool oven”. The 300°F in the steps is the modern equivalent, not the book's own figure.
Make the icing
In a bowl, mix icing sugar with egg whites and lemon juice.
Do not beat the egg whites.
Stir vigorously until a smooth, thick paste forms.
Apply and set
Use hands dipped in cold water to lay the icing on the cake.
Smooth the icing with an ivory knife dipped in cold water.
Let it harden in a cool oven (300°F / 150°C).
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.
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Sugar + lemontop 18% of all pairsSmell alikelowCooked together53,532 recipes
Shared aroma: 2-nonenal (fatty, green).
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Egg + lemontop 19% of all pairsSmell alikelowCooked together44,316 recipes
Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).
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Sugar + eggtop 21% of all pairsSmell alikemoderateCooked 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
- Provides sweetness and bulk, forming the body of the frosting.
- Egg whites
- Bind the sugar into a paste and help the icing set firm as it dries.
- Lemon juice
- Adds a little acidity that balances the sweetness of the sugar.
The step that matters
Stir vigorously until a smooth, thick paste forms. Icing sugar has lumps and the egg whites must be fully incorporated; if the mixture stays grainy or too loose, it will not spread smoothly or set firm. Adding egg whites gradually helps control thickness.
Swap the lemon
How well each one fits the dish's main ingredients (sugar, egg):
- Vanillafits better
- Raisinfits about as well
- Lemonthe original
- 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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