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Dessert

Foam Sauce

A sweet, frothy sauce made with boiling water, sugar, corn starch, butter, lemon juice, and baking soda.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Corn and lemon are a kitchen classic. They rank in the top 13% of all ingredient pairs, and cooks put them together in 1,927 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓

Foam Sauce

Ingredients

Directions

Make the sauce

  1. In a saucepan, combine boiling water, sugar, and corn starch.

  2. Add butter and bring to a boil until clear.

  3. Remove from heat and stir in lemon juice.

Foam and serve

  1. Just before serving, pour into a sauce dish containing baking soda.

  2. Stir and serve immediately to enjoy the foam.

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. Corn + lemontop 13% of all pairs
    Smell alikemoderate
    Cooked together1,927 recipes

    Shared aroma: 2-nonenal (fatty, green).

  2. Corn + buttertop 14% of all pairs
    Smell alikemoderate
    Cooked together7,345 recipes

    Shared aroma: 2,3-pentanedione (butter, sweet).

  3. Butter + lemontop 16% of all pairs
    Smell alikemoderate
    Cooked together41,227 recipes

    Shared aroma: 3-hexenal (apple, fruity).

  4. Sugar + buttertop 17% of all pairs
    Smell alikemoderate
    Cooked together98,233 recipes

    Shared aroma: guaiacol (smoky, sweet).

  5. Sugar + lemontop 18% of all pairs
    Smell alikelow
    Cooked together53,532 recipes

    Shared aroma: 2-nonenal (fatty, green).

Sugar and lemon barely smell alike, yet cooks put them together in 53,532 recipes: they work on texture and structure more than aroma.

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

What each ingredient does

Sugar
Provides sweetness and body to the sauce.
Corn starch
Thickens the sauce as it heats and helps it turn clear.
Butter
Adds fat for richness and a smoother mouthfeel.
Lemon juice
Adds acidity, which reacts with the baking soda to create foam.
Baking soda
Reacts with the acid to release carbon dioxide gas, producing the foam.

The step that matters

Pour and serve immediately. The foam comes from acid reacting with baking soda to release carbon dioxide bubbles. Those bubbles collapse quickly, so the sauce should be poured just before serving and eaten right away.

Swap the lemon

How well each one fits the dish's main ingredients (sugar, corn, butter):

  1. Vanillafits better
  2. Coconutfits better
  3. Figfits better
  4. Lemonthe original

Fit is the average pairing score against sugar, corn, butter. 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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