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Tomato Catsup

A tomato-based condiment made by boiling tomatoes and onions, seasoning, reducing, adding vinegar, and bottling.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 13 ingredients
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Why it works: Onion and garlic match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 29,058 recipes. Both carry furaneol, which smells caramel, strawberry. The science ↓

Tomato Catsup

Ingredients

Directions

Make the ketchup

  1. Boil the tomatoes and onions together until soft.

  2. Press through a colander, then strain the liquid through a fine sieve.

  3. Put the liquid over the fire with the seasoning and boil for 5 hours, stirring occasionally.

  4. When reduced by nearly half and thick, add the vinegar and remove the bag of celery seed.

Bottle and store

  1. When the catsup is cold, bottle it and seal the corks.

  2. Store in a cool, dark place.

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. Onion + garlictop 1% of all pairs
    Smell alikestrong
    Cooked together29,058 recipes

    Shared aroma: furaneol (caramel, strawberry).

  2. Parsley + peppertop 2% of all pairs
    Smell alikestrong
    Cooked together34,122 recipes

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

  3. Tomato + garlictop 3% of all pairs
    Smell alikemoderate
    Cooked together14,076 recipes

    Shared aroma: furaneol (caramel, strawberry).

  4. Garlic + parsleytop 4% of all pairs
    Smell alikestrong
    Cooked together9,308 recipes

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

  5. Clove + peppertop 5% of all pairs
    Smell alikestrong
    Cooked together17,451 recipes

    Shared aroma: ethyl octanoate (fruity, wine).

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 body, flavour and liquid that reduces into the thick ketchup.
Onions
Add savoury sweetness and body as they soften and blend into the base.
Vinegar
Adds acidity that sharpens the flavour and helps preserve the ketchup.
Sugar
Adds sweetness that balances the acidity of the vinegar and tomatoes.

The step that matters

Long reduction after adding the vinegar. Boiling for hours thickens the tomato liquid by evaporating water. Stopping early leaves a thin sauce, and the vinegar is added only once it is reduced, so the flavour stays sharp rather than cooked away.

Swap the mace

How well each one fits the dish's main ingredients (tomato, onion, garlic, parsley, sugar, clove, pepper):

  1. Thymefits better
  2. Cuminfits better
  3. Oreganofits better
  4. Macethe original

Fit is the average pairing score against tomato, onion, garlic, parsley, sugar, clove, 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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