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Tomato Catsup

A preserved tomato sauce made by simmering tomatoes, onions, salt, sugar, cinnamon, and vinegar for six hours, then sieving and bottling.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Tomato and onion are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 20,633 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Tomato Catsup

Ingredients

Directions

The book gives no cooking times; the times in the steps were added in transcription, so check for doneness rather than trusting the clock.

Prepare

  1. Chop the tomatoes and onions.

  2. In a large pot, combine tomatoes, onions, salt, sugar, cinnamon, and vinegar.

Cook and finish

  1. Boil slowly for 6 hours.

  2. Pass the mixture through a sieve.

  3. Add chilies for extra flavor if desired.

  4. Bottle the catsup.

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 + oniontop 8% of all pairs
    Smell alikemoderate
    Cooked together20,633 recipes

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

  2. Sugar + cinnamontop 10% of all pairs
    Smell alikelow
    Cooked together30,779 recipes

    Shared aroma: guaiacol (smoky, sweet).

  3. Tomato + cinnamontop 11% of all pairs
    Smell alikemoderate
    Cooked together1,348 recipes

    Shared aroma: beta-phellandrene (minty, terpene).

  4. Onion + vinegartop 14% of all pairs
    Smell alikemoderate
    Cooked together18,226 recipes

    Shared aroma: acetic acid (sour, vinegar).

  5. Sugar + vinegartop 15% of all pairs
    Smell alikemoderate
    Cooked together20,806 recipes

    Shared aroma: beta-damascenone (apple, rose).

Sugar and cinnamon barely smell alike, yet cooks put them together in 30,779 recipes: they 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
Form the bulk of the sauce, providing body, acidity and flavor as they cook down.
Onions
Add savory depth and aroma that builds as they soften during the long boil.
Salt
Seasons the sauce and helps draw moisture out of the tomatoes and onions.
Sugar
Balances the acidity of the tomatoes and vinegar and adds sweetness.
Vinegar
Adds sharp acidity that brightens the flavor and helps preserve the sauce.

The step that matters

Boil slowly for 6 hours. A slow, long simmer lets water evaporate gradually so the sauce thickens without scorching on the bottom. Too high a heat can burn the sugars and cause sticking, so the pot needs regular stirring and gentle heat throughout.

Swap the onion

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

  1. Capsicumfits better
  2. Cucumberfits better
  3. Mustardfits better
  4. Onionthe original

Fit is the average pairing score against tomato, sugar, cinnamon, vinegar. 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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