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Red Tomato Catsup

A tomato-based condiment made with tomatoes, onions, vinegar, sugar, spices, and salt.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Red Tomato Catsup

Ingredients

Directions

Prepare the tomatoes

  1. Wash the tomatoes and place them in a kettle with the chopped onions.

  2. Boil until tender enough to run through a fine sieve to remove all seeds.

  3. Pour the tomato and onion mixture into a granite kettle.

Make the ketchup

  1. Add vinegar, sugar, white pepper, cayenne, dry mustard, ginger, and salt.

  2. Cook while stirring frequently until it thickens, avoiding rapid boiling.

Bottle and seal

  1. Can the catsup in bottles, cork, seal with sealing wax, and dip the cork end in melted paraffin wax when cold.

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

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

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

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

  3. Vinegar + mustardtop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

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

  5. Pepper + gingertop 9% of all pairs
    Smell alikestrong
    Cooked together6,800 recipes

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

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

What each ingredient does

Tomatoes
Provide the bulk, body and flavour base of the ketchup.
Onions
Add savoury sweetness and aromatic depth to the tomato base.
Vinegar
Adds acidity that sharpens flavour and helps preserve the ketchup.
Sugar
Adds sweetness that balances the acidity and helps thicken the sauce.

The step that matters

Cook slowly while stirring. Rapid boiling can scorch the sugar-rich tomato mixture on the base of the kettle and burn it. Gentle cooking with frequent stirring lets the water evaporate evenly so the sauce thickens smoothly without sticking or burning.

Swap the white pepper

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

  1. Garlicfits better
  2. Turmericfits better
  3. Corianderfits better
  4. White pepperthe original

Fit is the average pairing score against tomato, onion, vinegar, sugar, pepper, mustard, ginger. 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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