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Tomato Ketchup

A homemade tomato ketchup made with tomatoes, spices, vinegar, and optional garlic.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 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 Ketchup

Ingredients

Directions

  1. Combine skinned tomatoes, salt, black pepper, allspice, red pepper, mustard, and chopped onions in a pot.

  2. Add sharp vinegar and simmer for 3 to 4 hours.

  3. Strain the mixture through a wire sieve.

  4. Bottle the ketchup and seal tightly.

  5. If desired, add garlic juice when cool.

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. Allspice + mustardtop 2% of all pairs
    Smell alikestrong
    Cooked together1,928 recipes

    Shared aroma: methyleugenol (clove, spice).

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

    Shared aroma: furaneol (caramel, strawberry).

  4. Pepper + allspicetop 5% of all pairs
    Smell alikestrong
    Cooked together6,395 recipes

    Shared aroma: estragole (anise, licorice).

  5. Mustard + garlictop 6% of all pairs
    Smell alikestrong
    Cooked together4,053 recipes

    Shared aroma: linalool (floral, citrus).

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 and provide its main flavour and body.
Onions
Add savoury depth and sweetness as they soften during simmering.
Sharp vinegar
Adds acidity that brightens the flavour and helps preserve the ketchup.
Mustard
Contributes sharp, pungent flavour that rounds out the sauce.

The step that matters

Simmer for 3 to 4 hours. Long simmering evaporates water and concentrates the tomatoes into a thick, rich sauce. Stopping early leaves it thin and watery, and the flavours stay raw rather than blended.

Swap the garlic

The recipe marks garlic as optional. How well each one fits the dish's main ingredients (tomato, pepper, allspice, mustard, onion, vinegar):

  1. Thymefits better
  2. Tarragonfits about as well
  3. Garlicthe original
  4. Celeryfits about as well

Fit is the average pairing score against tomato, pepper, allspice, mustard, onion, 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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