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Tomato Catsup

A homemade tomato sauce made by boiling tomatoes with vinegar, salt, sugar, mustard, and cayenne 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

  1. Wash and chop the tomatoes.

  2. Combine all ingredients in a large pot.

  3. Boil the mixture for 3 hours, stirring occasionally.

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. Vinegar + mustardtop 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

Ripe tomatoes
Provide the main bulk, flavor, and liquid that cooks down into the ketchup.
Vinegar
Adds acidity that sharpens flavor and helps preserve the finished ketchup.
Sugar
Adds sweetness that balances the acidity and tomato tang.
Salt
Seasons the ketchup and enhances the overall flavor.

The step that matters

Boil the mixture for 3 hours, stirring occasionally. Long simmering evaporates water and concentrates the tomatoes into a thick sauce. Stirring prevents the sugars and solids from scorching on the bottom of the pot, which would leave a burnt taste.

Swap the tomato

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

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

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