The Quickest Way To Preserve Your Veggies

These speedy tricks will help lock in the most nutrition from your summer harvest.

August 29, 2016
blanching vegetablesPhotograph by Rasica/Shutterstock

Gardeners have many choices for preserving their hard-earned harvest when the growing season is done, some requiring elaborate setups and more than a minimal understanding of food science. But in every kitchen, you'll find an appliance that offers a quick and foolproof way to capture the taste, texture, and nutrition that we all treasure in fresh-picked produce. We're talking, of course, about your freezer.

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Even after you pick your crops, enzymes continue to break down the nutrients, convert sugars to starches, and generally degrade flavor and texture. Blanching with steam or boiling water stops this action and preserves fresh-picked color. Tests have shown that, after nine months, vegetables that were blanched before freezing retain up to 1,300 percent more vitamin C and other nutrients than vegetables frozen without blanching. 

Steam blanching does the best job of preserving color, flavor, nutrition, and texture, says H. William Schafer, Ph.D., an extension food technologist with the University of Minnesota.

Water blanching tends to leach out water-soluble vitamins. Soaking vegetables to clean them can also literally wash away nutrients; better to rinse and brush them quickly under cold running water. Water blanching is more effective at getting rid of yeasts, molds, and bacteria if they are present and for removing cabbageworms from cauliflower and broccoli.

With either method, timing is key. Under-blanching can actually encourage quality-zapping enzymes.

steam blanching
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Steam Blanching

Clean and chop vegetables as if you are using them right away. Add one to two inches of water to a pot and bring to a boil. Using a basket or loose cheesecloth, suspend a layer of the prepared vegetables just over the boiling water and cover. When steam begins to escape, start timing. Halfway through the blanching process, check to make sure that the vegetables are not clumping together and that they are cooking evenly. Then remove the basket, cool, dry, and pack the vegetables. 

water blanching
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Water Blanching

Weigh prepared vegetables to make one-pound portions. Boil one gallon of water in a large kettle and place vegetables in a mesh or blanching basket and set in the boiling water. Start timing when water returns to a boil. Once the vegetables are finished, remove, cool, dry, and pack them away. 

blanching vegetables
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Take The Plunge

"The quicker you cool vegetables after blanching, the more color, texture, and flavor you will retain," says Schafer. Cool them for about the same amount of time they were blanched—twice as long for corn on the cob (here's how to blanch and freeze sweet corn). Use the ice bath method or place vegetable pieces in a container and set that container in a larger container filled with ice water. To prevent ice buildup on the vegetables once they're in the freezer, dry them before packing. Spread paper towels over cloth towels and place the blanched vegetables on top. A table fan will help speed drying.

freeze vegetables
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Pack It Up

To keep vegetable pieces from freezing together, some people spread them out on trays and freeze them before packing into bags—a process called tray packing. For most vegetables, this is not necessary, though it does help with fruit and certain crops such as peas, corn (off the cob), and beans. For most other vegetables, just pack pieces as tightly as possible into freezer containers or bags—pressing or sucking excess air out of the bags, date them, and freeze them.

Be sure your freezer is set at 0 degrees or cooler; higher temperatures will decrease their shelf life, Schafer says. "Oxygen-bearing packets and freeze-thaw cyclings also have negative effects on quality and can accelerate some nutrient loss." While most vegetables will keep 12 to 18 months in the freezer, plan to use them by the time your next crop is ready for the picking.

blanching asparagus
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Best And Worst For Blanching And Freezing

Cucumbers, lettuce, tomatoes, watermelon, and other vegetables that contain a lot of water or have a delicate cell structure do not freeze well. You can puree and then freeze tomatoes.

Your best bet for blanching and freezing vegetables is to use the following:

Asparagus: blanch for 2 to 4 minutes
Beans: 3 minutes
Beets: until tender
Broccoli: 3 minutes
Brussels sprouts: 3 to 5 minutes
Carrots: 2 to 5 minutes
Cauliflower: 3 minutes
Corn on the cob: 7 to 11 minutes
Eggplant: 4 minutes
Peas: 2 minutes
Peppers: 2 to 3 minutes 

If you are using the steam blanching method, mutiply the suggested blanching times by 1½.