Why it works: Tomato and lemon are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 4,592 recipes. Both carry 3-hexenal, which smells apple, fruity. The science ↓
Tomato- Jam
Ingredients
Directions
Prepare the tomatoes
Scald the ripe tomatoes and peel them.
Place the peeled tomatoes in a preserving kettle and cook gently until tender.
Rub the cooked tomatoes through a sieve using a potato masher.
Make the jam
Weigh the tomato pulp and return it to the kettle with an equal weight of sugar.
Add the grated rind and juice of the two lemons for each pound of pulp.
Boil the mixture until it looks clear and thickens when cooled on a saucer.
Jar
Cool slightly and transfer to air‑tight glass jars or glasses covered with paper.
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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Tomato + lemontop 11% of all pairsSmell alikemoderateCooked together4,592 recipes
Shared aroma: 3-hexenal (apple, fruity).
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Sugar + lemontop 18% of all pairsSmell alikelowCooked together53,532 recipes
Shared aroma: 2-nonenal (fatty, green).
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Tomato + sugartop 33% of all pairsSmell alikelowCooked together4,667 recipes
Shared aroma: beta-damascenone (apple, rose).
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
- Ripe tomatoes
- Provide the bulk of the pulp that becomes the jam.
- Sugar
- Adds sweetness and, in quantity, helps the jam thicken and keep.
- Lemons
- Add acidity and pectin-rich rind that help the jam set.
The step that matters
Boil until it sets. Tomatoes are low in pectin and acid, so the jam must boil long enough for the sugar and concentrated pulp to thicken. Underboiling leaves it runny; the saucer test checks the set.
Swap the tomato
How well each one fits the dish's main ingredients (sugar, lemon):
- Arrowrootfits better
- Sweet potatofits better
- Kalefits better
- Tomatothe original
Fit is the average pairing score against sugar, lemon. 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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