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Tomato Catsup

A thickened tomato sauce made with tomatoes, mustard, salt, vinegar, sugar, and red pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Tomato and pepper are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 17,923 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Tomato Catsup

Ingredients

Directions

Prepare

  1. Wash and cut up the tomatoes.

Cook and strain

  1. Boil the tomatoes until tender, then strain.

  2. Add mustard, salt, vinegar, sugar, and red pepper.

  3. Boil until the mixture thickens to your liking.

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

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

  2. Mustard + vinegartop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Mustard + peppertop 9% of all pairs
    Smell alikemoderate
    Cooked together15,430 recipes

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

  4. Tomato + mustardtop 11% of all pairs
    Smell alikemoderate
    Cooked together2,482 recipes

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

  5. Vinegar + peppertop 14% of all pairs
    Smell alikemoderate
    Cooked together27,814 recipes

    Shared aroma: 4'-methylacetophenone (bitter almond).

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

What each ingredient does

Tomatoes
Form the body of the sauce and supply most of its flavor and thickness.
Vinegar
Adds sharp acidity that balances the sweetness and gives ketchup its tang.
Sugar
Adds sweetness that offsets the acidity of the tomatoes and vinegar.
Mustard
Adds a sharp, pungent flavor that deepens the savory taste.
Red pepper
Adds a gentle background heat.

The step that matters

Boil until the mixture thickens to your liking. Thickening comes from water evaporating as the tomato solids concentrate. Stopping too early leaves the ketchup thin, while over-reducing makes it stiff and pasty once it cools.

Swap the tomato

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

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

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