Canning Lemon Curd

Normally a recipe for boiling water canning calling for ¾ cup of butter and eggs would send me running the other way. I would worried about botulism, but this recipe is from the National Center for Home Food Preservation that thoroughly tests their recipes before recommending them to the public.  A lot of research money and testing at The University of Georgia in Athens, GA has gone into this recipe. With that being said, this is not the type of recipe that you want to get creative with. Do not make substitutions or changes to this recipe. Sometimes with canning creativity can be dangerous, so it is better to go with a tested recipe rather than risk getting sick from your home canned products.

I have a lot of notes on this recipe for those not as familiar with cooking and canning:

1.       Superfine sugar can economically be made in your kitchen by running regular granulated sugar through a food processor or blender for 1 minute. The sugar should not be as fine as powdered sugar, but it should be finer than granulated sugar. If you are not comfortable making your own superfine sugar, then you can find super fine sugar at some grocery stores in the baking section or at specialty baking stores, but it will cost you more than regular granulated sugar.

2.       The lemon zest in this recipe must be fresh. Dehydrated lemon zest will not work in this recipe. To make zesting a lemon easier, use a microplate grater. A microplate grater will allow just the yellow part of the peel to come off leaving behind the bitter white part of the peel. A box grater is not recommended for zesting.

3.       Bottled lemon juice must be used in this recipe. Fresh lemon juice can vary in acidity which can make this recipe unsafe for canning so only bottled lemon juice is recommended for this canning project.

4.       If you do not have a double boiler, then you can easily make one by placing a large bowl (at least 1 ½ quart capacity) on top of a pot. The bowl should rest part of the way down inside the pot and fit snugly.

5.       At 168 degrees F my lemon curd changed color and texture. The top of the mixture went from being pale yellow from the butter to a beautiful bright yellow that you would expect in lemon curd. The mixture also began to thicken. This is where stirring becomes essential because you do not want to burn your lemon curd to the bowl.

6.       When taking the temperature of the lemon curd, make sure you are not touching your thermometer to the sides or bottom of the bowl. You want an accurate temperature for this recipe.

7. Your boiling water canner must be heated to 180 degrees F before the jars are added. Do not add the jars if the water is hotter than 180 degrees. When you add the jars to the hot water bath, the water will stop boiling and you will have to bring the jars in the hot water bath back up to boiling to start your process time. The process time does not start until the water is back up to a boil over the tops of the jars.

Don’t let all of my notes scare you away from making this recipe. This lemon curd is worth all the extra notes. The lemon curd has a nice sweet tart taste that makes a great cake filling. The curd has a pudding like texture. A small dab of this lemon curd is excellent in a small bowl of homemade yogurt. This lemon curd must be used quicker than most boiling water canning recipes. This lemon curd is shelf stable for only 4 months, so plan accordingly.  

Ingredients from National Center for Home Food Preservation yield about 4 half pint jars

2 1/2 cups super fine sugar (see note 1)
1/2 cup lemon zest (see note 2)
7 large egg yolks
4 large eggs
1 cup bottled lemon juice (see note 3)
3/4 cup unsalted butter, chilled, cut into 1/2" pieces

Special Equipment
Zester
Double Boiler (see note 4)
Thermometer
Mesh strainer
Large pot with rack on bottom for boiling water canning

Directions

1. Add enough water to hot water bath to cover full jars by two inches. Heat the boiling water bath to 180 degrees F. Do not over heat the water.

2. Mix the lemon zest with the sugar. Make sure to cover all the lemon zest with sugar. Set aside for 30 minutes.

3. Heat the water in the bottom half of the double boiler until gently boiling. The water level should not touch the top bowl.

4. Whisk eggs together until well mixed. Whisk in the sugar and lemon zest mixture slowly until smooth. Mix in the lemon juice. Add the butter pieces to the mixture.

5. Transfer the lemon mixture to the top of the double boiler.

6. Add the thermometer to the lemon mixture. Stir constantly.

7. Cook the lemon curd to 170 degrees F (see notes 5 and 6.)

8. Remove the curd from the heat.

9. Strain the curd to remove the zest.

10. Stir the curd for another 5 minutes until the curd is the desired thickness. My curd thickened within 3 minutes after removing from the heat.

11. Place curd in hot sterile jars leaving 1/2 inch head space. Place hot lids on the jars and adjust the two piece lids.

12. Place the jars in the hot water bath (see note 7). The water is cease to boil. Bring the water bath back to a boil. This will take about 30 minutes. The process time does not start until the water bath is back to a boil. Process for 15 minutes.