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Tomato Ketchup, No. 1

A homemade tomato ketchup made by boiling tomatoes, onions, peppers, and spices, then bottling while hot.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Ginger and cinnamon match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 6,380 recipes. Both carry estragole, which smells anise, licorice. The science ↓

Tomato Ketchup, No. 1

Ingredients

Directions

Prepare

  1. Chop the peppers and onions.

  2. Combine all ingredients in a pot.

Cook and bottle

  1. Boil for about three hours, stirring frequently.

  2. Bottle the ketchup while hot.

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. Ginger + cinnamontop 1% of all pairs
    Smell alikestrong
    Cooked together6,380 recipes

    Shared aroma: estragole (anise, licorice).

  2. Onion + mustardtop 6% of all pairs
    Smell alikestrong
    Cooked together9,259 recipes

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

  3. Cinnamon + mustardtop 7% of all pairs
    Smell alikestrong
    Cooked together1,581 recipes

    Shared aroma: guaiacol (smoky, sweet).

  4. Tomato + peppertop 7% of all pairs
    Smell alikemoderate
    Cooked together17,923 recipes

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

  5. Mustard + vinegartop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

What each ingredient does

Tomatoes
Provide the main body, moisture and fresh tomato flavour that the long cooking concentrates and thickens.
Vinegar
Adds sharp acidity that gives the ketchup its tang and helps keep it stable.
Sugar
Adds sweetness that balances the acidity of the vinegar and tomatoes.
Onions
Add savoury depth and aroma as they soften into the sauce.
Green peppers
Contribute a vegetal bitterness and aroma that adds background flavour.

The step that matters

Boiling for about three hours with frequent stirring. Slow boiling evaporates water so the sauce thickens and its flavours concentrate. Sugar and tomato solids can scorch on the bottom of the pot, so frequent stirring prevents burnt flavour.

Swap the onion

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

  1. Capsicumfits better
  2. Horseradishfits better
  3. Broccolifits better
  4. Onionthe original

Fit is the average pairing score against tomato, pepper, sugar, ginger, cinnamon, mustard, 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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