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
Remove the green skin from the watermelon rind and cut it into pieces.
Weigh the pieces and use 1½ pounds of sugar for each pound of rind.
Line a kettle with green vine leaves.
Layer the rind with sugar, covering each layer with vine leaves.
Pour enough water to cover the mixture and place a thick cloth over the kettle.
Simmer for 2 hours, adding a few bits of alum.
Spread the rind on a dish to cool.
Make the syrup
Melt the sugar with 1 pint of water for every 1½ pounds of sugar and mix in the beaten egg white.
Boil and skim the sugar until clear.
Add the rind and 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, using 1 lemon per quart of syrup.
When the syrup thickens enough to hang from a spoon, it is done.
Place the rind in jars and pour the syrup over it.
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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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).
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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
- Watermelon rind
- Forms the bulk of the preserve and takes on sweetness and texture from the syrup.
- Loaf sugar
- Sweetens the rind and, at high concentration, preserves it by drawing out water.
- Lemon juice
- Adds acidity that brightens the sweet syrup and helps balance its flavor.
- Alum
- Firms the rind's texture so it stays crisp during long simmering.
The step that matters
Boiling the syrup to the thickness test. Syrup must be cooked until it is concentrated enough to hang from a spoon. Too little boiling leaves it thin and it may not preserve the rind well; over-boiling makes it hard and sugary.
Swap the lemon
How well each one fits the dish's main ingredients (sugar, egg, syrup):
- Vanillafits better
- Raisinfits better
- Lemonthe original
- Figfits about as well
Fit is the average pairing score against sugar, egg, 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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