Freezing is a great way to preserve rhubarb. And frozen rhubarb works just as well as fresh in recipes like rhubarb compote. But there are a couple of steps you need to take before you freeze it to end up with a quality product. Giving the rhubarb stalks a quick blanching in boiling water before freezing them ensures that they retain a good texture and their rosy color for when you get around to cooking with them.
A single-layer initial freeze prevents the rhubarb pieces from clumping together. The fact that they stay loose is a big advantage when, for example, you have a quart-size container of frozen rhubarb but need to take out only a cup of it for a recipe.
The following are the easy steps for freezing rhubarb.
How to Blanch and Freeze Rhubarb
If you are harvesting your own rhubarb from the garden, be sure to cut off all of the toxic leafy green parts away from the leafstalk. Only the leafstalk is edible.
- Wash the rhubarb leafstalks in cold water. Cut the stalks into 1/2- to 1-inch pieces.
- While you're washing and chopping the rhubarb, prepare a large pot of boiling water.
- Fill a large bowl with ice and cold water for an ice bath.
- Drop the cut rhubarb pieces into the pot of rapidly boiling water, and let them cook for 1 minute. You can also steam the rhubarb for 1 minute rather than boiling it.
- Immediately drain the rhubarb in a colander, then transfer it to the bowl of ice water. This stops the cooking process. Gently stir the pieces in the ice bath, and let them chill in the bath for about 2 minutes.
- Drain the rhubarb pieces well in a colander.
- Spread the blanched and chilled rhubarb pieces in a single layer on a baking sheet (if desired, line the baking sheet with parchment paper first). Put the pan in the freezer, uncovered, for about 2 hours.
- Transfer the frozen rhubarb to freezer bags or other airtight containers. Tightly seal the containers, and label them with the date.
Tips for Freezing Rhubarb
- Use frozen rhubarb just as you would fresh. Because of the blanching step, the color of recipes made with frozen rhubarb will match the rosy color of the fresh leafstalks. And the tangy flavor will be just as terrific.
- Frozen rhubarb will keep for 1 year. It is still safe to eat after that, but its quality will decline.
- It is not necessary to thaw frozen rhubarb before cooking with it. However, if you are baking with rhubarb, it's best to thaw it first, as it shrinks a bit after thawing.
- One pound of fresh rhubarb yields about 3 cups of chopped pieces when it is raw or frozen; the same amount cooks down to about 2 cups.
- If the rhubarb stalks have tough strings (common with field-grown varieties), remove the strings before chopping the stalks. The normal stringiness of the stalks softens during cooking, but it's best to remove tough strings before freezing or cooking.