Why it works: Sugar and syrup match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 5,842 recipes. Both carry ethanol, which smells alcoholic, ethereal. The science ↓
To Preserve Watermelon Rind and Citron
Ingredients
Directions
Prepare the rind
Line a kettle with green vine leaves.
Add the watermelon rind without sugar.
Cover the rind with a layer of vine leaves.
Pour in enough water to cover it.
Place a thick cloth over the kettle.
Simmer for 2 hours, adding a few bits of alum.
Spread the watermelon rind on a dish to cool.
Make the syrup
In a separate pot, melt the sugar with 1 pint of water.
Mix in the beaten egg white. Boil and skim until clear.
Add the cooled rind to the syrup.
Boil for 2 hours.
Remove the rind.
Boil the syrup again.
Pour the syrup over the rind and let it sit overnight.
Finish and jar
The next morning, boil the syrup with lemon juice until it thickens enough to hang from a spoon.
Place the rind in jars and pour the syrup over it.
Let it sit before using.
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 + syruptop 6% of all pairsSmell alikestrongCooked together5,842 recipes
Shared aroma: ethanol (alcoholic, ethereal).
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Melon + lemontop 14% of all pairsSmell alikemoderateCooked together362 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
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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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Lemon + syruptop 20% of all pairsSmell alikelowCooked together2,235 recipes
Shared aroma: ethanol (alcoholic, ethereal).
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
- Melon rind
- Forms the preserve's body, becoming tender and translucent as it cooks in syrup.
- Sugar
- Sweetens the preserve and, once concentrated in syrup, helps preserve the rind.
- Alum
- Firms the rind's texture so it stays crisp rather than turning soft during simmering.
- Beaten egg white
- Binds impurities that rise as foam, which are skimmed off to clarify the syrup.
- Lemon juice
- Adds acidity that balances the sweetness and helps the syrup thicken.
The step that matters
Boil and skim the syrup until clear. Egg white coagulates and carries cloudy impurities to the surface as foam. Skimming it off clarifies the syrup, and boiling too hard or stirring too much can break the foam back into the liquid.
Swap the melon
How well each one fits the dish's main ingredients (sugar, egg, lemon, syrup):
- Vanillafits better
- Orangefits better
- Raisinfits better
- Melonthe original
Fit is the average pairing score against sugar, egg, lemon, syrup. 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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