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Tomato Catsup

A thick tomato sauce made by boiling tomatoes, seasoning with spices, and adding vinegar and sugar.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Mustard and celery are a kitchen classic. They rank in the top 2% of all ingredient pairs, and cooks put them together in 4,169 recipes. Both carry guaiacol, which smells smoky, sweet. The science ↓

Tomato Catsup

Ingredients

Directions

Prepare the tomatoes

  1. Cut the tomatoes and place them in a porcelain-lined kettle.

  2. Boil the tomatoes until they are completely mashed.

  3. Strain the mixture through a colander.

Cook the ketchup

  1. Add the salt, mace, black pepper, cayenne, ground mustard, and celery seed.

  2. Boil for 6 hours, stirring constantly during the last hour to prevent burning.

  3. About 30 minutes before finishing, add the vinegar and brown sugar.

Bottle

  1. Bottle the catsup when it is cold and seal.

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. Mustard + celerytop 2% of all pairs
    Smell alikemoderate
    Cooked together4,169 recipes

    Shared aroma: guaiacol (smoky, sweet).

  2. Tomato + celerytop 4% of all pairs
    Smell alikemoderate
    Cooked together3,377 recipes

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

  3. Pepper + celerytop 5% of all pairs
    Smell alikestrong
    Cooked together16,012 recipes

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

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

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

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

    Shared aroma: isobutyraldehyde (malty, green).

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 bulk that the ketchup is built from.
Vinegar
Adds acidity that sharpens flavor and helps preserve the finished ketchup.
Brown sugar
Adds sweetness that balances the acidity of the tomatoes and vinegar.
Salt
Seasons the ketchup and helps draw out flavor from the tomatoes.
Ground mustard
Adds a sharp, pungent note that rounds out the spice blend.

The step that matters

Stirring during the last hour of boiling. As water evaporates the mixture thickens and sugars concentrate, so it can scorch on the bottom of the kettle. Constant stirring prevents burning and off flavors.

Swap the mace

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

  1. Tarragonfits better
  2. Dillfits better
  3. Thymefits better
  4. Macethe original

Fit is the average pairing score against tomato, pepper, mustard, celery, vinegar, 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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