Rhubarb is a wonderful, tart summertime harvest that responds well to freezing so that you may enjoy it all year round. Follow these guidelines for the best tasting and looking results.
Selecting High-Quality Rhubarb
Choose crisp, brightly-colored stalks. Usually you should choose firm red stalks, but there do exist some varieties where color is not an indication of ripeness. You can test this in your plant simply by tasting green and red stalks to compare. Keep in mind that smaller stalks have more flavor and are less fibrous. Stalks that are as thick as your fingers and thumb are the best for harvesting.
Twist the stalks rather than cutting them. Twisting will cause the plant to delay flowering, prolonging the harvest. Discard the leaves immediately. Rhubarb leaves contain a very strong toxin called oxalic acid. Never cook with them and be sure to safely discard them away from children and pets.
Preparing for Freezing
Wash stalks and cut away any brown or otherwise unpleasant spots. This will help the longevity of your rhubarb. Trim and cut into pieces 1 to 2 inches in length or as you normally would for baking.
Blanching is a method of preserving the color of the rhubarb by boiling before freezing. Place the rhubarb in boiling water for one minute and rinse in cool water to quickly remove the heat. This process dramatically preserves the color and texture of frozen rhubarb. However, blanching does not noticeably affect taste and can be easily skipped if the look of the rhubarb is not important to you.
Two Freezing Methods
To freeze the rhubarb unsweetened and as-is, simply pack the cut pieces into a suitable freezing container. Vacuum packed bags work the best for any long-term freezing, including rhubarb. However, plastic freezer bags and containers can keep the rhubarb for up to a year anyway. Just be sure that they have been designed for the freezer as some plastic tends to warp or crack. Label the container and place in the freezer.
Alternatively, you can sweeten the rhubarb by freezing it in a syrup. Usually baking with rhubarb entails sweetening the tart vegetable, so this second method of freezing the rhubarb along with syrup can cut down on future baking time and allows the sugar to penetrate more deeply. To make the syrup, boil equal parts sugar and water for three minutes and allow to cool to room temperature. Then add your syrup to the rhubarb in a suitable container, label and freeze. Do not blanch the rhubarb in syrup.
Thawing Your Rhubarb
You are probably planning on using the rhubarb for baking or making jam, in which case it is not necessary to keep the rhubarb crisp. If this is so, you can simply microwave the rhubarb on the defrost setting per manufacturer specifications. However, if you want to preserve some crunch, then place the rhubarb in room temperature on a towel so that it can drain excess moisture. Wipe of any excess frost beforehand. If your rhubarb has suffered freezer burn, defrost in this manner until it is nearly thawed and then place the pieces in your oven on its lowest setting for twenty minutes.