Why it works: Apple and lemon are a kitchen classic. They rank in the top 14% of all ingredient pairs, and cooks put them together in 7,551 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓
Quince or Apple Custards
Ingredients
Directions
Make the custard
Combine apple juice, lemon juice, and sugar in a saucepan; bring to a boil.
Quickly stir in the well-beaten eggs in small portions.
Thicken the custard by placing the jug in a pan of boiling water, stirring gently.
Variation
For quince custards, follow the same steps but omit the lemon juice.
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.
-
Apple + lemontop 14% of all pairsSmell alikemoderateCooked together7,551 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
-
Apple + sugartop 18% of all pairsSmell alikelowCooked together16,478 recipes
Shared aroma: beta-damascenone (apple, rose).
-
Lemon + sugartop 18% of all pairsSmell alikelowCooked together53,532 recipes
Shared aroma: 2-nonenal (fatty, green).
-
Lemon + eggtop 19% of all pairsSmell alikelowCooked together44,316 recipes
Shared aroma: (e,e)-2,4-decadienal (fatty, deep fried).
-
Sugar + eggtop 21% of all pairsSmell alikemoderateCooked together122,807 recipes
Shared aroma: 2-nonenal (fatty, green).
Apple and sugar barely smell alike, yet cooks put them together in 16,478 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
- Eggs
- Set the custard into a thick, spoonable texture as they cook.
- Apple juice
- Forms the liquid base that the eggs thicken into custard.
- Sugar
- Sweetens the custard and balances the tartness of the juice.
- Lemon juice
- Adds acidity that brightens the flavor of the custard.
The step that matters
Adding the eggs to the hot mixture. Eggs scramble if they meet very hot liquid all at once. Adding them quickly in small portions while stirring spreads the heat, and gentle heating in a water bath lets the custard thicken smoothly.
Swap the apple
How well each one fits the dish's main ingredients (lemon, sugar, egg):
- Orangefits better
- Vanillafits better
- Limefits better
- Applethe original
Fit is the average pairing score against lemon, sugar, egg. 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.
You might also like
The free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.
Apple Pudding256 recipes
Lemon Cake228 recipes
Lemon Ice147 recipes
Lemon Sherbet103 recipes