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 Pkeserve Watermelon Rind and Citron
Ingredients
Directions
Prepare the rind
Remove the green skin from the watermelon rind and cut it into pieces.
Weigh the rind pieces and use 1.5 pounds of sugar for each pound of rind.
Line a kettle with green vine leaves and add the rind pieces, layering with more vine leaves.
Pour enough water to cover the rind and cover the kettle with a thick cloth.
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 1.5 pounds of sugar, mixing in beaten egg white.
Boil and skim the sugar until clear.
Add the rind and boil for 2 hours.
Remove the rind and boil the syrup again.
Pour the syrup over the rind and let it sit overnight.
Finish and store
The next morning, boil the syrup with lemon juice until thick enough to hang from a spoon.
Put the rind in jars and pour the syrup over it.
Allow to 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.
-
Sugar + syruptop 6% of all pairsSmell alikestrongCooked together5,842 recipes
Shared aroma: ethanol (alcoholic, ethereal).
-
Sugar + lemontop 18% of all pairsSmell alikelowCooked together53,532 recipes
Shared aroma: 2-nonenal (fatty, green).
-
Egg + lemontop 19% of all pairsSmell alikelowCooked together44,316 recipes
Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).
-
Lemon + syruptop 20% of all pairsSmell alikelowCooked together2,235 recipes
Shared aroma: ethanol (alcoholic, ethereal).
-
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 main body of the preserve, becoming tender and translucent as it cooks in syrup.
- Loaf sugar
- Sweetens the preserve and, as the syrup thickens, preserves the rind and gives it a glossy texture.
- Lemon juice
- Adds acidity that brightens the sweet syrup and helps it set to a thick consistency.
- Beaten egg white
- Clarifies the syrup by binding impurities that are then skimmed off, leaving it clear.
The step that matters
Boiling the syrup until it hangs from a spoon. Sugar syrup must reach a high enough concentration to set and preserve the rind. Stopping too early leaves it thin and watery, while boiling too long can make it crystallise or darken.
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.
You might also like
Lemon Cake228 recipes
Lemon Ice147 recipes
Lemon Sherbet103 recipes
Lemon Custard64 recipesThe free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.