Understanding Lemon Curd: Does It Thicken as It Cools?

If you’re a fan of tangy and sweet flavors, you may have heard of lemon curd. This versatile spread is made by cooking together egg yolks, sugar, butter, and lemon juice until thick and creamy. But what exactly is it? And how do you make the perfect batch every time? In this article, we’ll answer all your burning questions about lemon curd – from whether it thickens as it cools to how best to store it for later use. Plus, we’ll share expert tips on making the most delicious lemon curd imaginable.

What is Lemon Curd?

Lemon curd is a delicious spread made from lemon juice, butter, sugar, and eggs. It has a smooth and creamy texture with a tangy and sweet taste that makes it perfect for spreading on toast, muffins, scones or using as a filling in cakes or tarts.

Brief History of Lemon Curd

The origin of lemon curd can be traced back to the 19th century when citrus fruits were commonly used to make jams and preserves. It became very popular in England during World War II when rationing forced people to find alternatives to fresh fruit. Since then it has become a standard dessert topping for many households around the world.


  • 6 large egg yolks
  • 1 cup granulated sugar
  • 1/2 cup fresh lemon juice (about 4 lemons)
  • Zest of two lemons (about 2 tablespoons)
  • 1 stick unsalted butter (8 tablespoons), cut into small pieces and chilled

Basic Recipe of Lemon Curd

  1. In a heavy-bottomed saucepan over medium heat, whisk together the egg yolks and sugar until well blended.
  2. Add the lemon juice, zest, and butter.
  3. Cook while stirring constantly for about 10-12 minutes or until thickened enough to coat the back of a spoon.
  4. Pour into sterilized jars for storing if not consuming right away.

This simple yet versatile recipe takes only about 15-20 minutes to prepare but requires constant attention during cooking since it can easily burn if left unattended. Once prepared, lemon curd can be stored in an airtight container in the refrigerator for up to two weeks, but it usually disappears much faster given its deliciousness!

Does Lemon Curd Thicken as It Cools?

If you’ve ever made lemon curd before, you might have noticed that it has a runny consistency when first cooked. But after letting it cool in the fridge, it becomes thick and luscious. This leaves many people wondering – does lemon curd thicken as it cools? The answer is yes!

How Lemon Curd Thickens

Lemon curd thickens through a process called coagulation. As the egg yolks and sugar cook over low heat, they start to thicken and turn into a pudding-like mixture. However, for the mixture to fully solidify, it needs something to hold onto. This is where butter comes in.

When the butter is added to the mixture while still hot, its fat molecules start to coat and stabilize the proteins already present in the eggs. This makes the mixture more viscous or sticky and gives us that signature thickness we all love about lemon curd.

Factors That Affect Thickening

The thickness of your lemon curd depends on several factors:

  • The proportion of ingredients used (i. e., more yolks create thicker custard)
  • Cooking time and temperature (higher heat leads to faster coagulation)
  • The amount of butter added (more butter creates a smoother mouthfeel but can also make it thinner)

Scientific Explanation of Cooling and Thickening

Lemon curd continues to thicken upon cooling due primarily to starch retrogradation occurring between amylose molecules trapped during gelation with amylopectin whose branched structure excludes other amylose from entering further tightening up colloidal structures within the fluid. [^1] To put it more simply, the cooling process causes the amylose molecules to line up and bond together. This strengthens the structure of the curd and makes it thicker and velvety.

[^1] Slade, Louise; Levine, Harry; Schoch, Timothy (2003). “Gelation of concentrated maltodextrin solutions”. Carbohydrate Polymers. 53: 39–48.

Tips for Making Perfect Lemon Curd

Common Mistakes to Avoid

Making lemon curd may seem simple, but there are a few common mistakes to avoid:

  • Not straining the mixture: Straining helps remove any cooked egg bits or pieces of lemon zest that didn’t get fully incorporated into the curd. Leaving them in can affect the texture of your final product.
  • Overcooking the curd: Overcooked lemon curd will become thick and grainy rather than smooth and creamy. Make sure you are cooking it over low heat and stirring constantly as it thickens.
  • Using too much butter: Adding too much butter can cause your lemon curd to separate or turn greasy. Stick to the recommended amount in your recipe.
  • Adding acid too early: If you add acidic ingredients like lemon juice or vinegar too early, they can react with the eggs and cause them to scramble. Always add acids towards the end of cooking once the eggs have started to thicken.

Troubleshooting Tips

If you encounter any issues while making your lemon curd, here are some troubleshooting tips:

  • If your curd is lumpy or has small bits of cooked egg, strain it through a fine-mesh sieve before using.
  • If your mixture becomes grainy or separates when adding butter, try heating it up very gently (in a double boiler if possible) and whisking vigorously until it comes back together.
  • If you accidentally added acid too early and caused scrambling, immediately take the pot off of heat and whisk in some cold butter until everything emulsifies again.
  • If your curd is too thick or thin, adjust the amount of eggs or butter in your recipe accordingly.

Variations and Flavor Additions

Lemon curd is delicious on its own, but there are many ways to customize it:

  • Add lavender, thyme or basil for a fragrant twist.
  • Make it boozy by adding gin, limoncello or champagne instead of some lemon juice.
  • Sweeten with honey instead of sugar for a more nuanced flavor.
  • Add fruit puree such as strawberry puree to make different berry flavors of citrus curd.
Pro tip: Use leftover lemon curd to make macarons, tarts, pies and other desserts!

How to Store and Use Lemon Curd

When it comes to lemon curd, proper storage is key for maintaining its flavor and texture. Here are some tips:

  • Store in an airtight container in the refrigerator for up to two weeks.
  • Ensure that the curd is completely cool before putting it in the fridge.
  • To extend its shelf life, freeze the curd for up to six months.

Creative ways to use lemon curd

Lemon curd can be used beyond just being a spread on toast or scones. Here are some creative ways you can make use of this versatile ingredient:

  • Add a dollop on top of pancakes or waffles.
  • Make your own lemon yogurt by adding spoonfuls of lemon curd into plain Greek yogurt.
  • Spread it on top of pound cake or angel food cake slices.
  • Add some flavor and tartness to smoothies with a spoonful of lemon curd.
  • Create mini fruit tarts by spreading a layer of lemon curd inside pre-made mini pastry shells, and topping with fresh berries or sliced fruit. s

Recipe ideas for using leftover lemon curd

If you have some leftover lemon curd, here are some simple recipes you can whip up:

    Try swirling a little bit of lemon curd into cream cheese for a tangy bagel spread.

These are just some of the many ways you can store and use lemon curd. Get creative in the kitchen and experiment with new recipes to enjoy this delicious ingredient!


In conclusion, lemon curd is a delicious spread that can add a burst of fresh flavor to any dessert or breakfast item. Whether you’re using it in pies or tarts or simply spreading it on toast, following the right steps can help ensure that your lemon curd comes out perfectly every time.


Can I freeze lemon curd?

Yes! Lemon curd freezes very well – just be sure to store it in an airtight container.

How long does homemade lemon curd last?

Homemade lemon curd will typically keep for up to two weeks in the fridge.

What are some creative ways to use leftover lemon curd?

Lemon curd can be used in a variety of ways – try swirling it into yogurt for added flavor or using it as a filling for cupcakes or macarons.

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