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Tomato Ketchup

A preserved tomato sauce made with tomatoes, salt, sugar, spices, vinegar, and shallots, boiled and bottled.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Vinegar and shallot are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 2,374 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓

Tomato Ketchup

Ingredients

Directions

Make the tomato pulp

  1. Crush and boil the tomatoes for 1 hour.

  2. Press through a fine sieve and return to the kettle.

  3. Boil for 3 more hours until it becomes a heavy pulp.

Season and finish

  1. Add salt, sugar, special spices, and vinegar (with shallots boiled for 20 minutes).

  2. Boil the ketchup for an additional 15 minutes.

  3. Bottle hot and seal with Phoenix Caps.

  4. Process the bottles in a boiling water bath if desired.

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. Vinegar + shallottop 12% of all pairs
    Smell alikemoderate
    Cooked together2,374 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  2. Tomato + shallottop 12% of all pairs
    Smell alikemoderate
    Cooked together583 recipes

    Shared aroma: 2,4-decadienal (seaweed).

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

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

  4. Tomato + vinegartop 16% of all pairs
    Smell alikemoderate
    Cooked together5,063 recipes

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

  5. Sugar + shallottop 28% of all pairs
    Smell alikelow
    Cooked together817 recipes

    Shared aroma: 1-penten-3-one (fish, pungent).

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

What each ingredient does

Tomatoes
Provide the bulk of the pulp, flavour and body once reduced by long boiling.
Sugar
Adds sweetness and balances the acidity of the vinegar and tomatoes.
Vinegar
Adds acidity that gives ketchup its tang and helps preserve it.
Salt
Seasons the ketchup and enhances the flavour of the other ingredients.
Shallots
Add a mild savoury, aromatic flavour to the sauce.

The step that matters

Boil until a heavy pulp forms. Long boiling evaporates water and concentrates the tomato solids, so the ketchup thickens. Stopping early leaves it thin and more prone to spoiling once bottled.

Swap the tomato

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

  1. Mustardfits better
  2. Beetrootfits better
  3. Chivefits better
  4. Tomatothe original

Fit is the average pairing score against sugar, vinegar, shallot. 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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