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Tomato Catsup

A thick tomato sauce made with tomatoes, onions, peppers, vinegar, mustard, spices, and sugar.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Pepper and clove match in chemistry and in kitchens. They rank in the top 5% of all ingredient pairs, and cooks put them together in 17,451 recipes. Both carry ethyl octanoate, which smells fruity, wine. The science ↓

Tomato Catsup

Ingredients

Directions

Prepare

  1. Press the ripe tomatoes through a colander.

Cook

  1. In a large pot, combine the pressed tomatoes, salt, onions, sweet red peppers, vinegar, mustard, cloves, black pepper, and brown sugar.

  2. Boil the mixture until it thickens to your desired consistency.

  3. Adjust seasoning to taste.

Recipe from a historical cookbook (Internet Archive).

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.

  1. Pepper + clovetop 5% of all pairs
    Smell alikestrong
    Cooked together17,451 recipes

    Shared aroma: ethyl octanoate (fruity, wine).

  2. Onion + mustardtop 6% of all pairs
    Smell alikestrong
    Cooked together9,259 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

  3. Tomato + peppertop 7% of all pairs
    Smell alikemoderate
    Cooked together17,923 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

  4. Vinegar + mustardtop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  5. Mustard + clovetop 8% of all pairs
    Smell alikestrong
    Cooked together3,829 recipes

    Shared aroma: methyleugenol (clove, spice).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Ripe tomatoes
Provide the main body, moisture and tomato flavor that the ketchup is built on.
Vinegar
Adds acidity that gives the ketchup its tang and helps preserve it.
Brown sugar
Adds sweetness that balances the acidity and rounds out the flavor.
Onions
Add savory depth and aromatic sweetness to the sauce.
Sweet red peppers
Add body and mild sweetness to the sauce.
Mustard
Adds sharp, savory flavor that complements the tomatoes and vinegar.

The step that matters

Boil until thickened. Ketchup thickens only as water evaporates during boiling. Stopping too early leaves it thin and watery, while cooking too long can make it overly dense and sticky. Tomatoes vary in water content, which is why the vinegar may need reducing.

Swap the tomato

How well each one fits the dish's main ingredients (onion, pepper, vinegar, mustard, clove, sugar):

  1. Horseradishfits better
  2. Capsicumfits better
  3. Shallotfits better
  4. Tomatothe original

Fit is the average pairing score against onion, pepper, vinegar, mustard, clove, sugar. 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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