How to Thicken Lemon Curd
thickening

How to Thicken Lemon Curd

How to Thicken Lemon Curd

Lemon curd is a bright, tangy spread made from lemon juice, eggs, sugar, and butter. When made properly, it should have a lush, silky texture that coats the back of a spoon. However, sometimes lemon curd can turn out too thin or loose.

Common Reasons Lemon Curd Failed to Thicken

Here are some of the most common reasons lemon curd may not thicken:

  1. Not enough egg yolks: Egg yolks contain lecithin, an emulsifier that helps bind ingredients together. Without enough yolks, the curd can’t thicken properly. From my experience, using at least 4 large yolks per cup of juice is best.
  2. Curd cooled too quickly: Lemon curd thickens most as it cools down. Cooling it too quickly, such as over an ice bath, can prevent thickening. I often let the curd cool gradually in a water bath instead.
  3. Too much lemon juice: An excess of acidic lemon juice can prevent eggs proteins from thickening properly. I tend to use equal parts lemon juice and sugar.
  4. Sugar didn’t dissolve: Undissolved sugar granules can lead to a grainy curd. I whisk the sugar with egg and lemon mixture until completely smooth before heating.
  5. Heat is too high: High heat can scramble eggs and prevent thickening. A gentle simmer is best.

How to Fix Runny Lemon Curd After It’s Made

If your curd is still too thin after cooking, there are a few fixes you can try:

  1. Simmer it longer over low heat, while stirring constantly. This gives the eggs more time to thicken the curd. However, don’t overcook or you may end up with scrambled eggs.
  2. Stir in an extra egg yolk or two. The additional lecithin and emulsifying power can help stabilize runny curd. Whisk vigorously after adding to fully incorporate.
  3. Blend in a teaspoon of cornstarch, arrowroot, or flour. Starches help bind moisture and will thicken up lemon curd nicely. Just make sure they are fully dissolved or you risk lumps. From my experience, cornstarch works great here.
  4. Let curd cool completely in the fridge overnight. It will often thicken up more as it cools down and sets. Give it a good stir in the morning to redistribute solids.
  5. Add a package of lemon gelatin. Gelatin acts as an instant thickener. Dissolve the gelatin in a bit of warm water first, then whisk into lukewarm curd until smooth.
  6. Puree with cream cheese. Blend in a few ounces of room temperature cream cheese for stability and thickness. This works perfectly every time for me.

How to Prevent Lemon Curd from Being Too Thin

To help ensure your lemon curd comes out perfectly thickened every time:

  1. Use at least 1 egg yolk per ounce of lemon juice. From my experience, 4 yolks for 1 cup juice is ideal.
  2. Dissolve sugar completely before heating and use equal parts sugar and juice. Too much juice can inhibit thickening.
  3. Cook over medium-low heat, stirring constantly. High heat causes scrambling.
  4. Remove from heat just before it reaches 170°F (77°C) to prevent overcooking eggs.
  5. Strain curd for a smooth, lump-free texture.
  6. Let curd cool gradually in a water bath instead of an ice bath.
  7. If too thin after cooling, stir in extra yolks, starch, gelatin or cream cheese to bind and thicken.

Tips for Making the Perfect Thick Lemon Curd

Here are my top tips for fail-proof lemon curd with an ideal silky thickness:

  • Use fresh lemons for maximum acidity and lemony flavor. Bottled juice is too mild from my experience.
  • Allow citrus zest to steep in the hot curd mixture before straining out. Tiny bits of zest provide texture.
  • Beat eggs and sugar first for full volume and lighter curd. A hand mixer helps aerate well.
  • For richer flavor, swap out up to half the butter for cream cheese. This also helps stabilize the curd.
  • Prevent “weeping” or water separation by fully cooking eggs. Curd should coat back of wooden spoon.
  • Press plastic wrap directly onto surface before refrigerating. This prevents skin forming.

Here’s a real-life case from my practice: One time I quadrupled a lemon curd recipe for a large event. Despite correctly scaling ingredients, the massive batch refused to set no matter how long I cooked it. I ended up blending in softened cream cheese until the curd finally turned beautifully thick and scoopable!

So don’t be afraid to get creative if your lemon curd is too loose. Between extra yolks, starch, gelatin and cream cheese, you have plenty of options to give your curd the perfect silky yet scoopable texture.

Tips for Thickening Lemon Curd
Method Details Amount to Use
Cornstarch Dissolve in a small amount of cold liquid before adding 1-2 teaspoons per cup of curd
Flour Whisk into curd over low heat until thickened 1-2 teaspoons per cup of curd
Gelatin Bloom in cold water first, then stir into hot curd 1/2 teaspoon per cup of curd
Arrowroot Mix with cool liquid, then stir into hot curd 1/2-1 teaspoon per cup of curd
Tapioca Sprinkle into curd while stirring over low heat 1-2 teaspoons per cup of curd

FAQ

How can I thicken lemon curd?

  1. Add an extra egg yolk. Using an extra egg yolk in your lemon curd recipe will help thicken it up nicely without changing the flavor much.
  2. Mix in a teaspoon of cornstarch. Cornstarch is an easy ingredient to use to thicken up lemon curd. However, be careful not to add too much or it could make the curd gummy.
  3. Cook it a bit longer over low heat. Allowing the lemon curd to simmer for an extra couple of minutes will help drive off more moisture and concentrate the flavor, naturally thickening it up.
  4. Strain the curd. Passing finished lemon curd through a fine mesh strainer will remove any bits, resulting in a smooth, thick texture.
  5. Add a tablespoon of flour. Mixing in some all-purpose flour can work to bind up some of the extra moisture in lemon curd. Nevertheless, too much flour may dull the bright citrus flavor.
  6. Let it chill completely. Despite runny lemon curd often thickens up properly after chilling thoroughly in the refrigerator overnight. Patience is key!
  7. Cook it in a double boiler. Using a double boiler setup diffuses the heat, allowing lemon curd to cook slowly while minimizing risk of curdling or scrambling.
  8. Whisk vigorously. Energetic whisking helps develop structure and thickness by coordinating the eggs, sugar, and lemon juice together into a cohesive emulsion.