Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and 81,283 recipes mention both. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓
Tomato Soup
Ingredients
Directions
Make the soup
Boil the tomatoes and water for 1 hour.
Add the butter, flour, salt, pepper, and baking soda.
Finish and serve
Then add the milk and let everything come to a boil.
Strain the soup and serve.
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.
Photo for illustrative purposes only · Contact us to use it
Explore the science
The flavor team
The pairs that carry this dish. Each one is judged two ways: how much aroma chemistry they share, and how many recipes mention both.
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Butter + milktop 7% of all pairsAroma overlapmoderateMentioned together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Tomato + peppertop 7% of all pairsAroma overlapmoderateMentioned together17,923 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Butter + flourtop 12% of all pairsAroma overlaplowMentioned together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Flour + milktop 14% of all pairsAroma overlaplowMentioned together78,219 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Tomato + milktop 15% of all pairsAroma overlapmoderateMentioned together2,226 recipes
Shared aroma: 1-octen-3-one (mushroom, metallic).
Butter and flour share little aroma chemistry, yet 124,287 recipes mention both: they likely 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
- Tomatoes
- Provide the main body, flavor, and acidity of the soup.
- Butter
- Adds fat for richness and a smoother mouthfeel.
- Flour
- Thickens the soup as it cooks, giving it body.
- Baking soda
- Neutralizes some tomato acidity, making the milk less likely to curdle.
- Milk
- Adds creaminess, mild sweetness, and a softer, paler color.
The step that matters
Adding the milk to the tomato base. Tomatoes are acidic, and acid combined with heat can cause milk proteins to curdle. Baking soda reduces that acidity, which is why it is added before the milk. Letting the soup come to a boil after adding milk increases the risk of curdling, so the soup should be watched closely.
“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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