Easy What Are Common Mistakes When Making Lemon Curd?

Lemon curd is one of those recipes that looks simple on the surface but can quickly become frustrating if you’re not careful. When it’s made well, lemon curd is silky, glossy, tangy, and smooth—perfect for tarts, cakes, scones, pavlovas, and countless desserts. But when something goes wrong, you end up with curd that’s grainy, runny, too thick, curdled, lumpy, or overly sweet.

If you’ve ever wondered, “Why isn’t my lemon curd turning out right?”, you’re not alone. Many home bakers run into the same issues. The good news? Most mistakes are easy to understand and even easier to avoid once you know what to look out for.

In this article, we’ll walk through the most common mistakes when making lemon curd, why they happen, and how you can avoid them so your curd turns out perfectly smooth every time.

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Basics of Lemon Curd

Before exploring mistakes, it helps to understand what lemon curd actually is. Lemon curd is a simple mixture of:

Lemon juice
Lemon zest
Eggs
Sugar
Butter

These five ingredients transform into a thick, custard-like spread when gently heated. The eggs thicken the mixture, the lemon adds tang, the sugar balances acidity, and the butter creates the smooth, creamy texture we love.

Because lemon curd is essentially a citrus custard, it requires careful attention to temperature, timing, and technique. One small misstep can affect the final texture.

Let’s explore the mistakes that cause problems and how to fix them.

1. Using Too Much Heat

One of the biggest causes of failed lemon curd is overheating. Lemon curd should be heated gently and gradually. When the heat is too high, the eggs scramble, creating a curdled or grainy mixture.

Why This Mistake Happens

Many people assume that higher heat will make the curd thicken faster. Instead, it cooks the eggs too quickly and unevenly.

What Happens to the Curd

Lumps form
Egg bits appear
Texture becomes grainy
Curd may separate

How to Avoid This Mistake

Cook on low to medium-low heat
Stir continuously
Use a heavy-bottomed pan
Consider using a double boiler if you’re new to making curd

Think of lemon curd like a delicate custard—it needs patience, not speed.

2. Not Stirring Constantly

Lemon curd requires frequent stirring because eggs and sugar need even heating to form a smooth texture.

Why It Happens

Some assume that lemon curd behaves like jam and can be left alone between stirs.

Why Stirring Matters

Without constant movement:

The eggs heat unevenly
Hot spots form
The mixture sticks to the bottom
The curd becomes lumpy

How to Fix It

Use a whisk or heatproof spatula and stir the entire time until it thickens. Your arm may get tired, but the smooth result is worth it.

3. Adding Butter Too Early

Butter should always be added after the curd finishes cooking, not before.

Why Adding Butter Early Is an Issue

If butter melts in the pan at the start:

It interferes with the eggs’ thickening
The texture becomes greasy
The curd may not set properly

Correct Technique

Once the curd has thickened and is removed from the heat, stir in the butter cubes. The residual heat melts the butter gently, creating a glossy, velvety consistency.

Adding butter at the end also helps cool the curd, stopping the cooking process.

4. Not Straining the Curd

Even if you’re careful, lemon zest, egg threads, or lumps can appear in lemon curd. Not straining it is one of the most common mistakes beginners make.

Why It Matters

Straining removes:

Zest fibers
Undissolved egg bits
Seeds
Any lumps

When to Strain

Always strain the curd while it’s still warm, immediately after cooking. Warm curd passes through a sieve more easily.

5. Using the Wrong Pan

The pan you choose affects flavour and texture more than most people expect.

Common Pan Mistakes

Using aluminium or unlined metal
Using a thin-bottomed pan

Why This Matters

Lemon juice reacts with some metals, leaving your curd with:

A metallic taste
A dull colour
A slightly grey tint

Thin pans also cause uneven heating, increasing the risk of curdling.

Best Pan Type

Use:

Stainless steel
Enameled saucepan
A heavy-bottomed non-reactive pot

This keeps flavours clean and heating consistent.

6. Rushing the Cooking Time

Lemon curd takes around 10–15 minutes to thicken (sometimes longer). Many people remove it too early, thinking it will thicken more as it cools.

Why This Is a Problem

Under-thickened curd stays runny even after cooling.

What Properly Cooked Curd Looks Like

Coats the back of a spoon
Leaves a clean line when you drag your finger across
Looks glossy and slightly thick

The Fix

Be patient. If it hasn’t thickened yet, keep stirring. Slow and steady wins the lemon curd race.

7. Using Whole Eggs Incorrectly

Some recipes use whole eggs, others use only yolks, and some use a mixture. Mistakes happen when the egg ratio is off.

Common Mistake

Using fewer egg yolks or more whole eggs than needed results in:

A thinner curd
A less creamy texture

Why Yolks Matter

Egg yolks add richness and help stabilize the curd. Too many whites can make your curd watery or firm in an unpleasant, jelly-like way.

How to Avoid the Issue

Follow the recipe carefully and don’t adjust the egg quantity unless you understand how custards behave.

8. Not Balancing Sugar and Lemon

Lemon curd needs a balance between sweet and tart. A common mistake is adjusting ingredients without considering their effect on texture.

Too Much Lemon Juice

Curd becomes:

Too acidic
Runny
More difficult to thicken

Too Little Sugar

Curd becomes:

Overly sharp
Harsh on the palate

The Solution

Stick to a tested ratio. If adjusting sweetness, do it slightly.

Here’s a simple guideline:

1 lemon (juice + zest): 1 egg : 3 tablespoons sugar: 1 tablespoon butter

9. Not Allowing the Curd to Cool Properly

Cooling is part of the curd-making process. If you rush it, the texture can suffer.

What Happens If You Skip Cooling

The curd forms condensation
Water collects on the surface
The texture becomes uneven

Cooling Tip

Place plastic wrap or parchment directly on the surface of the warm curd to prevent a skin from forming.

Then refrigerate until completely chilled.

10. Overcooking the Curd

Just like undercooking, overcooking is another frequent mistake.

How Overcooking Happens

Leaving the curd on the heat after thickening
Not removing it promptly
Using high heat

What Overcooked Curd Looks Like

Grainy
Thick and rubbery
Separated

How to Avoid It

As soon as the curd thickens, remove it from the heat and stir in the butter.

11. Using Bottled Lemon Juice

Fresh lemons and bottled juice are not the same. Bottled lemon juice contains preservatives and lacks the aromatic oils found in lemon zest.

Why Bottled Juice Causes Problems

The flavour is dull
The acidity is inconsistent
The curd may not set the same way

Always Use Fresh Lemons

Zest is essential for real lemon flavour.

12. Storing Curd Incorrectly

Improper storage leads to curd that spoils, separates, or grows a watery layer on top.

Storage Mistakes

Not sealing the container
Leaving air pockets
Keeping it too long
Storing while still warm

Correct Storage

Cool completely
Store in an airtight jar
Refrigerate up to 1–2 weeks
Freeze up to 3 months

13. Making Curd Without a Thermometer (If You’re New)

You don’t need a thermometer to make lemon curd, but if you’re learning, it helps.

Perfect Temperatures

Eggs scramble above ~80°C
Curd thickens between 72°C and 75°C

Why Beginners Benefit

A thermometer removes guesswork and prevents curdling.

How to Make Perfect Lemon Curd Every Time

Here’s a quick, reliable method for smooth, silky lemon curd:

Ingredients

3 lemons (zest + juice)
3 eggs
150g sugar
100g butter

Method

Whisk eggs and sugar. Add lemon juice and zest. Cook over low heat, stirring constantly, until thick. Remove from heat and stir in butter. Strain and chill.

This simple method avoids nearly all the common mistakes.

Final Words

Lemon curd can feel tricky at first, but once you understand the common mistakes, it becomes one of the easiest and most rewarding recipes you’ll ever make. The key is gentle heat, constant stirring, patience, and fresh ingredients. When done right, you get a smooth, bright, tangy curd that adds magic to every dessert it touches.