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 ↓
Barley-sugar
Ingredients
Directions
Make the syrup
Combine the sugar and spring water in a pot.
Add enough egg white to clarify the mixture.
Boil until it begins to whiten and thicken.
Stir in the lemon juice and boil quickly until it reaches the desired consistency.
Optionally, add a few drops of essence of lemon just before removing from heat.
Shape and set
Pour onto a lightly oiled marble slab or shallow dish.
When the edges start to harden, shape into sticks, lozenges, or balls.
If it cools too quickly, place the vessel in a pan of water and gently reheat.
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
- Sugar
- Forms the glassy candy base that sets hard as it cools.
- Egg white
- Clarifies the syrup by binding impurities so they can be skimmed off.
- Lemon juice
- Adds acidity that helps prevent the sugar from crystallizing.
The step that matters
Boiling to the desired consistency. Sugar must be cooked to the right concentration: too little and the candy stays sticky, too much and it becomes brittle or scorches. Stirring and watching closely helps the syrup reach the target stage evenly.
Swap the lemon
The recipe marks lemon as optional. 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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