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Grandma's Tomato Ketchup

A homemade tomato ketchup made by simmering tomatoes with salt, pepper, mustard, and vinegar.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
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Why it works: Tomato and pepper are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 17,923 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Grandma's Tomato Ketchup

Ingredients

Directions

  1. Combine the skinned tomatoes, salt, black pepper, and mustard in a large pot, then add a little sharp vinegar.

  2. Simmer slowly for 4 to 5 hours.

  3. Strain the mixture through a wire sieve.

  4. Bottle the ketchup and seal it tightly.

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

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

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

    Shared aroma: isobutyraldehyde (malty, green).

  3. Pepper + mustardtop 9% of all pairs
    Smell alikemoderate
    Cooked together15,430 recipes

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

  4. Tomato + mustardtop 11% of all pairs
    Smell alikemoderate
    Cooked together2,482 recipes

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

  5. Pepper + vinegartop 14% of all pairs
    Smell alikemoderate
    Cooked together27,814 recipes

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

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 liquid and body, and their pectin and sugars thicken the ketchup as it reduces.
Vinegar
Adds sharpness that balances the sweetness of the reduced tomatoes and helps preserve the ketchup.
Mustard
Adds a sharp, pungent flavour that rounds out the tomato taste.

The step that matters

Simmer slowly for 4 to 5 hours. Long, gentle simmering evaporates water and concentrates the tomatoes into a thick sauce. Too little reduction leaves it thin and watery, while a hard boil can scorch the bottom of the pot.

Swap the tomato

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

  1. Horseradishfits better
  2. Radishfits better
  3. Lettucefits better
  4. Tomatothe original

Fit is the average pairing score against pepper, 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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