Blanching — boiling vegetables for a specified length of time — is a simple but necessary task for freezing asparagus successfully. Like all vegetables, asparagus contains enzymes that ensure the asparagus plants mature and develop properly.
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Blanching your vegetables before freezing asparagus is key for maintaining flavor, texture, color and nutritional content.
Without blanching to stop the enzymes, the enzymes remain active, and the flavor, texture, color and nutritional content of the asparagus will be compromised. When properly blanched and packaged, asparagus retains its quality in the freezer for 10 to 12 months.
Store your fresh asparagus in the refrigerator, standing up in a container with the bottoms of the stalks in about 1 inch of water, as advised by the University of New Hampshire Cooperative Extension.
Read more: How to Cook Frozen Asparagus
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Step 1: Wash the Asparagus
Wash the asparagus under running water. Alternatively, fill a large bowl with cold water, then clean the asparagus by swishing it in the water. This method works best if the asparagus is dirty, as swishing it in water removes sand embedded in the tips of the asparagus spears.
Step 2: Sort By Size
Sort the asparagus into batches of small, medium and large spears, as larger spears require more blanching time than small, slender spears. Blanch and pack each size separately. Spears measuring more than 1/2 inch in diameter are considered to be large spears. Small spears are thin and have a diameter smaller than a pencil.
Step 3: Make Pieces Uniform
Cut large spears into 1- to 2-inch lengths. You can cut smaller spears or leave them whole.
Step 4: Boil Some Water
Bring a large kettle of water to a full boil. Use 1 gallon of water for each 1 pound of asparagus.
Step 5: Place Basket in Water
Place the asparagus in a metal basket or steamer. Immerse the basket immediately in the boiling water.
Step 6: Cover and Set Timer
Cover the kettle securely. Set your kitchen timer as soon as the water returns to a boil.
Step 7: Blanch By Size
Blanch small spears for 2 minutes, medium spears for 3 minutes and large spears for 4 minutes, as recommended by the University of Georgia.
Step 8: Cool Asparagus Rapidly
Fill a bowl with ice water. When the timer rings, quickly remove the strainer from the kettle, then plunge the asparagus in the ice water. Allow the asparagus to cool rapidly, adding extra ice if necessary. Cooling time is about the same as blanching time.
Step 9: Drain, Pack and Freeze
Drain the cooled asparagus thoroughly. Pack the asparagus in resealable freezer bags, making sure to squeeze out excess air, or airtight plastic containers. Label and date your asparagus, as advised by North Dakota State University.
Try This Before Freezing Asparagus
You can also blanch asparagus by steaming. The process is nearly identical to boiling, except the asparagus is placed in a steamer basket suspended above the water, instead of being placed in the water.
Steaming is slower, so add 50 percent more time. Blanch small spears for 3 minutes, medium spears for 4 1/2 minutes and large spears for 6 minutes.
Things You'll Need
Large kettle with cover
Metal basket or steamer
Resealable freezer bags or airtight plastic containers