Custards, creams & meringues
lemon curd
lemon curd · A cooked custard of butter, sugar, egg and citrus juice — distinguished from pastry cream by the absence of starch and by its higher proportion of fat. The classic British preserve, pale yellow, intensely aromatic and glossy, used as filling, spread and sauce.
The formula
1:1:1 butter : sugar : lemon juice
Scale by the butter weight. Example: 200 g butter → 200 g sugar, 150 g lemon juice (≈1 large lemon), 4 whole eggs + 2 yolks (≈160 g). Yields ~580 g. Use 2:1 yolk-to-white ratio for a richer, yellower curd; all-whole-egg for a lighter, paler result.
Identity
- Equal-weight butter and sugar, dissolved before eggs are added
- Cooked to 82–85 °C / 180–185 °F, never to a boil
- Strained through fine-mesh to eliminate cooked egg strands
- Butter added off-heat or at end of cooking; never boiled in
- Thickened by egg-protein coagulation and lemon-acid set, not by starch
Ingredients
| Fat | unsalted butter | Always unsalted, for precise seasoning control. Cold or room-temperature for late-stage incorporation. |
| Base | whole eggs + egg yolks | 3 yolks per 100 g butter gives the richest, most golden result; 2 whole eggs per 100 g butter gives a lighter, paler curd. All-whole-egg is acceptable; all-yolk produces a dense paste. |
| Acid | fresh lemon juice + finely grated zest | Use fresh juice only — bottled lacks volatile aromatics. Include zest for oils absent in juice. Approx 1 lemon per 100 g juice needed. |
| Seasoning | caster or ultrafine sugar | Fine grain dissolves readily at low temperature. Granulated works but requires more dissolving time before eggs are added. |
| Binder | optional 5 g cornstarch | Stabilises the set slightly and reduces risk of looseness. Unconventional in the classical British recipe but common in commercial and American variants. Increases shelf life slightly. |
| Seasoning | pinch of fine sea salt | Always. Salt amplifies lemon and sugar perception; omit only for strictly sweet applications. |
Method
- 1Combine butter, sugar, lemon juice and zest in a heavy-based saucepan. Heat over medium-low, stirring, until butter melts and sugar dissolves completely — the mixture should feel smooth when rubbed between fingers, approximately 50–60 °C.Sugar dissolution is essential before egg introduction; undissolved sugar causes grainy texture and localised scorching.
- 2Whisk eggs (and yolks) in a separate bowl. Slowly pour the hot lemon-butter mixture into the eggs while whisking constantly to temper — aim for a steady stream, adding no faster than ~1 part egg to 3 parts hot liquid per addition.Tempering prevents sudden egg-protein coagulation. Adding eggs directly to a hot mixture causes scrambling before the curd sets properly.
- 3Return the combined mixture to the pan. Cook over medium-low heat, stirring constantly with a flat wooden spoon or silicone spatula in wide, controlled strokes, until the curd reaches 82–85 °C (180–185 °F) and coats the back of a spoon.Egg proteins coagulate fully by 80–85 °C; beyond 90 °C the proteins tighten and release water, causing a loose, curdled texture. The curd will continue to thicken off-heat.
- 4Remove from heat immediately. Optionally strain through a fine-mesh sieve for a perfectly smooth finish. Add cold butter pieces (if using) and stir until fully incorporated — this drops the temperature rapidly and halts cooking.Straining eliminates any small cooked-egg threads. Cold butter shock-sets the emulsion and enriches the texture.
- 5Pot into a sterilised glass jar, press a disc of cling film directly onto the surface to prevent a skin forming, seal, and cool completely before refrigerating.Direct food-contact film prevents oxidative browning of the surface. Full cooling before refrigeration avoids condensation inside the sealed jar.
Techniques that matter
tempering
Prevents egg proteins from seizing or scrambling when introduced to heat; essential for any egg-thickened sauce or curd.
controlled coagulation
Egg-protein set occurs at 80–85 °C; controlling temperature prevents over-coagulation that produces a loose, weeping texture rather than a clean, spreadable set.
fat-in-water emulsion
Butter is melted into an aqueous phase (lemon juice + dissolved sugar); the egg emulsifies the fat droplets, creating the smooth, glossy, semi-solid texture characteristic of a curd.
citric-acid set
Lemon acid lowers the pH, partially denaturing egg proteins and enabling a softer set at lower temperature than a non-acidified custard. The acid also prevents sugar crystallisation and adds flavour.
Variations & derivatives
lime or orange curduniversal
Substitute equivalent juice and zest; lime produces a slightly looser set due to lower pH, orange yields a milder, sweeter curd.
passion-fruit curdSouth America / Pacific
Add 60–80 g strained passion-fruit pulp per 200 g butter base; higher pectin content makes this slightly thicker and more gel-like.
Italian crema al limoneItaly
Made zabaglione-style over a bain-marie with Marsala or Vin Santo, then finished with butter. Result is lighter and more ethereal.
whole-lemon curdcontemporary
Blends entire washed lemons (pith removed) to a pulp before cooking. Intensely aromatic, slightly bitter, spreadable.
crème de citron (Michalak)France
Adds gelatin (2 g per 250 g base) for a sliceable, mousse-like texture. Often paired with crémeux techniques for layered desserts.
Used in these dishes
Substitutions
- fresh lemon juice → bottled lemon juice — Lacks volatile aroma compounds (citral, limonene) that fresh zest and juice provide. Use only in emergencies; result will be flat and one-dimensional.changes result
- caster sugar → honey or glucose syrup — These are inverted/soft sugars; they prevent crystallisation but alter the set texture and caramelise differently. Honey should not exceed 30% replacement or the flavour overwhelms.
- egg yolks → whole eggs with added gelatin — Gelatin at 1–2% of total weight partially compensates for reduced yolk richness and improves sliceability, but changes the mouthfeel from a cream to a jelly.
Troubleshooting
Curd is thin and will not set
Eggs were overcooked past 90 °C; proteins tightened and expelled water. Or: insufficient cooking before cooling. → Return to pan, cook gently to 83–85 °C again while stirring, then cool properly. If still thin, add 5–10 g dissolved cornstarch per 500 g and cook to a second set.
Curd is grainy or gritty
Sugar was not fully dissolved before eggs were added; undissolved crystals persisted. Or: egg proteins have formed small clumps. → Strain through a fine-mesh sieve while warm and fluid. Whisk in a teaspoon of cold water if very thick; stir well and cool.
Curd is curdled or has broken
Heat was too high and egg proteins seized in the pan. Or: cold butter was added too quickly and the emulsion broke. → While still warm, process with an immersion blender for 30–60 seconds. Often the emulsion will re-form. If not, heat gently to 40 °C while whisking vigorously — this can rescue a broken curd.
Curd turned brownish or tastes cooked
Cooked at too high a temperature, activating Maillard browning; lemon colour degrades. → Use a water bath (bain-marie) for the cooking stage. Lemon curd should remain pale ivory to bright yellow, never tan. If already browned, the flavour is compromised; start fresh.