University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article
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FREEZING VEGETABLES
 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
           
If you have a large freezer, freezing vegetables right from the garden or local farm stand may be easier and longer lasting than traditional storage methods.  Most vegetables can be frozen quite easily.  Exceptions not to freeze are green onions, lettuce and other salad greens, cucumbers, and tomatoes (except for use in juices and cooking). 
           
First you should stock containers for freezing.  Be sure to use ones specifically for freezers, including plastic freezer bags and rigid plastic containers.  Products such as sandwich bags, bread bags, and dairy containers wont work well for storage.  They allow loss of moisture, which in turn leads to brownish-white spots known as "freezer burn".  Although dried-out produce isn't spoiled, it is often tough with odd flavors.
           
Another important key to preserving texture and flavor of frozen vegetables is "blanching" prior to freezing.  This is simply scalding vegetables in hot water or steam for a short time to stop enzyme action.  These enzymes in produce are responsible for their growth and maturation, so must be stopped prior to freezing.  Blanching times will vary with vegetables.  Too little time, and the enzymes keep working.  Too much time, and the vegetables come out of storage overcooked.
           
To blanch in boiling water, lower a pound of vegetables in a gallon of boiling water.  If steam blanching, suspend a thin layer of vegetables in a wire basket over one to two inches of boiling water in a kettle.  In the microwave, blanch two cups of vegetables at a time with one-quarter cup of water in a two-quart casserole.  Cover with plastic wrap, not a glass lid, to decrease blanching time.
           
After blanching, cool quickly in a large amount of cold water.  Running water or use of ice often helps.  When packing, since food expands, leave about a half-inch of space at the top in rigid containers.  In freezer bags, press the air out of the bag before closing.  These methods are "solid pack" in which case you thaw the whole container.  If you freeze the vegetables on a tray prior to packing, this method of "loose pack" allows you to pour out vegetables as needed.

 Here are some specific tips and blanching times for popular vegetables.
*Lima beans should be blanched from 2 to 4 minutes, depending on size, with the least time for the smallest beans.  Green beans can be left whole, or cut into short lengths.  Remove tips, and blanch for 3 minutes.
*Beets should be washed, sorted by size, and tops trimmed off but leaving a half-inch of stem.  Boil until tender—25 minutes for small beets, more for larger.  Cool, slice or cube to freeze.
*Wash and trim broccoli into pieces one to one to two inches across.  If you see insects, soak for a half hour in a solution of 4 teaspoons of salt in a gallon of water.  Blanch in water for 3 minutes, over steam for 5 minutes. Treat cauliflower the same.
*Similarly for Brussels sprouts and cabbage, check and treat if needed for insects. Remove coarse, outer leaves.  Wash, and sort sprouts by size, blanching 3 to 5 minutes, more for larger ones.  Cut cabbage into shreds or wedges, then blanch for one and a half minutes.
*Remove tops of carrots, then wash.  You can leave whole, or cut into sections or strips.  Blanch whole carrots 5 minutes, diced or sliced carrots for 2 minutes.
*Sweet corn can be left on the cob after husks and silks are removed.  Blanch small ears 7 minutes, large ears 11 minutes.  If cutting kernels off the cob, blanch for 4 minutes.
*Wash, peel, and cut eggplant into one-third inch thick slices.  Soak in the above salt solution for 5 minutes to preserve color.  Blanch for 4 minutes.
*Although you can't freeze salad greens, you can wash and blanch greens from beets, collards, turnips, spinach, and others similar.  Blanch tender greens one and a half minutes, other greens 2 minutes, except 3 minutes for collard greens.
*Peel, wash, and dice fully mature onions.  Loosely pack in freezer bags without blanching.
*Shell green peas, then blanch for one and a half minutes.  For snow peas, remove blossom ends and strings, then blanch whole for one and half to three minutes depending on size.
*Green or hot peppers should be washed, then cut into rings or slices and frozen without any heat treatment.
*Wash, peel, and cut potatoes into half-inch cubes.  Blanch for 5 minutes.  For hash browns, cook potatoes in jackets until almost done.  Cool, peel, and cut into desired shapes to freeze.
*Wash summer squash or zucchini, then cut into one-half inch slices to blanch for 3 minutes.
*For juice tomatoes, wash, sort by size, and cut into quarters.  Simmer for 5 to 10 minutes, then press through a sieve prior to cooling and freezing.  For stewed tomatoes, wash and scald for a minute to loosen the skin, then peel and core.  Quarter, simmer for 15 minutes, then cool.  For raw tomatoes, peel and core as above. Then quarter and put in containers, pressing down to release the juice.  Leave an inch of headspace in containers of tomatoes for the juice.

When cooking frozen vegetables, keep in mind all but corn on the cob (it should be partially thawed) should be cooked without thawing.  Since blanched vegetables have been partially cooked, they'll need less time than fresh vegetables, so cook only until tender.
             

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