MP-119-6
Issue Six
‘Sweet’ sweet corn
Patti Griffith, Nutrition and Food Safety Educator, University of Wyoming Cooperative Extension Service
Since the turn of the century, one problem with sweet corn is the sweet
flavor deteriorates rapidly after picking. In response, scientists bred varieties
not only for more sweetness but also to hold freshness and flavor longer.
These are referred to as “everlasting” varieties.
To ensure flavor, cook and eat corn as soon after picking as possible.
If corn must be stored for a short time, keep it very cold and at a high
humidity in the vegetable drawer of the refrigerator. This helps prevent
a tough, starchy-tasting product. Prepare corn for eating or preserving
quickly after harvest. At room temperature, harvested ears lose 50 percent
of their sugar within 24 hours.
Selecting Fresh Corn
Look for fresh husks with bright green color, silk ends free from decay
or worm injury, and stem ends not too discolored or dried. Select ears well
covered with plump, but not too mature, kernels. Indentations in the top
of each kernel are a sign of maturity. Avoid ears with undeveloped kernels,
unusually large kernels, or dark-yellow kernels because they can be tough
and not very sweet.
Home Canner’s Questions
“How sweet it is” could
refer to today’s patch of
sweet corn. It’s amazing
how scientists have
developed sweeter and
sweeter varieties through
hybridization.
processing green beans, the pressure dropped from the level
Q While
recommended in the U.S. Department of Agriculture’s (USDA)
Complete Guide to Home Canning.
Are they safe?
A
The beans cannot be considered safe for shelf storage. There are
several options:
1. Refrigerate the beans immediately, and eat
them as soon as possible.
2. Reprocess them for the full
amount of time, or
3. If the problem is detected during
processing, begin retiming for the
full amount of time after the pressure
again reaches the level recommended
in USDA’s Complete Guide to Home Canning. The
University of Wyoming Cooperative Extension Service
(UW CES) Food and Nutrition Web page at www.
uwyo.edu/cesnutrition/Food_Preservation.htm links to
on-line versions of USDA’s canning guidelines. Click
on the UW Resources link to access Wyoming-specific
versions of the guidelines (Preserving Food in Wyoming
link), or click on the Web Sites link to access the entire
USDA publication. In addition to guidance on food
preservation, the UW CES Food and Nutrition Web
site provides information and links in other subject
areas, including food preparation, food safety, food
storage, and a number of nutrition topics.
Print versions of the USDA canning publication and the
seven publications in the Wyoming series can be ordered
by e-mailing the UW College of Agriculture’s Resource
Center at [email protected] or calling the center at
(307) 766-2115. For more information on canning and
food preservation, call a local UW CES office. Contact
information is in your local phone directory and on-line at
http://ces.uwyo.edu/Counties.asp.
several jars of carrots, and I noticed the
Q Ilidscanned
were not concave and didn’t seal properly. Can I
reprocess them?
If no more than 24 hours have passed since the
food was processed, unsealed jars of food can be
reprocessed. If more than 24 hours have passed, the food
should be considered unsafe and should be discarded.
See graphic below from the National Center for Home
Food Preservation (www.uga.edu/nchfp) on how to test for
A
seals.
Q Which foods should be packed loosely?
A
For better heat penetration, loosely pack corn, peas,
lima beans, greens (turnip greens, beet greens,
spinach, and Swiss chard), red meats, chicken, and clams.
Q Why do lids sometimes discolor on the underside?
A
Chemical reactions between the metal and food acids
can sometimes cause dark spots on the lids. These are
harmless in cans of properly sealed and processed foods.
Canning Corn
Corn can be canned as whole-kernel or cream-style. Slight
differences in preparation can result in very different
processing times. When canning, follow tested recipes to
ensure a safe product (the addresses for Web sites containing
tested recipes are included in this fact sheet).
When canning corn as whole-kernel, use a sharp
knife and slice the kernels off from the top of the ear to
the bottom. Do not scrape the cob, as scraping will make
creamed corn.
For cream-style corn, select ears containing slightly
immature kernels. Cut corn from the cob at about the center
of the kernel. Scrape remaining corn from cobs with a table
knife. To each quart of corn and scrapings in a saucepan,
add two cups of boiling water. Heat the mixture to boiling.
Add 1/2-teaspoon salt to each jar, if desired. Fill pint jars
with hot corn mixture, leaving 1-inch headspace.
Do not can cream-style corn in quart jars. The larger
jar doesn’t allow the heat to properly penetrate throughout
the mixture. Follow recommended processing times for
altitude and whether using a dial-gauge pressure canner or
a weighted-gauge canner. For assistance, call a UW CES
county office. See contact information above.
Before storing canned corn, make sure the lids are
tightly vacuum sealed on cooled jars. Then remove screw
bands, wash the lids and jars to remove food residue, and
rinse and dry the jars. Label and date the jars, and store
them in a clean, cool, dark, dry place. For best quality,
store between 50 and 70 degrees Fahrenheit. Can only the
amount of food that will be used within one year.
Freezing Corn
Preparation – Select tender, freshly picked corn in
the milk stage. If a sweet, milky juice is released from the
kernels (milk stage), the corn is ready for harvest. Husk and
trim the ears, remove silks, and wash.
Corn on the cob – Blanch corn on the cob by
immersing the cobs in boiling water. Blanch small ears
(1 1/4 inches or less in diameter) for 7 minutes, medium
ears (1 1/4 to 1 1/2 inches in diameter) for 9 minutes, and
large ears (over 1 1/2 inches in diameter) for 11 minutes.
Cool promptly and completely to prevent a “cobby” taste.
Cooking may be stopped quickly by dunking the cobs into
ice water. After draining, package the corn and then seal
and freeze in plastic containers or plastic bags suitable for
freezing.
Whole-kernel
corn – Blanch corn
on the cob
4 minutes. Cool
promptly and
drain. Cut kernels
from the cob
about 2/3 the depth of the kernels. Package the corn, leaving 1/2-inch
headspace. Squeeze out air, seal, and freeze.
Cream-style corn – Blanch 4 minutes. Cool promptly and drain.
Cut kernel tips, and scrape the cobs with the back of a knife to remove
the juice and the heart of the kernel. Package the corn, leaving 1/2-inch
headspace. Squeeze out air, seal, and freeze.
Storage – Well-packaged frozen corn can be stored up to 9 months
at 0 degree Fahrenheit without loss of quality. Containers may be flexible
or rigid providing they don’t allow moisture to enter the container and
are leakproof, easy to seal and mark on, and designed to protect food
from absorbing off-flavors or odors in the freezer.
Pickled-Corn Relish
Yield: About 9 pints
10 cups fresh whole-kernel corn (16 to 20 medium-sized ears), or six
10-ounce packages frozen corn
2 1/2 cups diced sweet red peppers
2 1/2 cups diced sweet green peppers
2 1/2 cups chopped celery
1 1/4 cups diced onions
1 3/4 cups sugar
5 cups vinegar (5 percent)
2 1/2 T. canning or pickling salt
2 1/2 T. canning or pickling salt
2 1/2 t. celery seed
2 1/2 T. dry mustard
1 1/4 t. turmeric
Procedure: Boil ears of corn 5 minutes. Dip in cold water. Cut whole
kernels from cob, or use six 10-ounce packages of frozen corn. Combine
red and green peppers, celery, onion, sugar, vinegar, salt, and celery
seed in a saucepan. Bring to a boil, and simmer 5 minutes, stirring
occasionally.
Mix mustard and turmeric in 1/2 cup of the simmered mixture.
Add this mixture and corn to the hot mixture. Simmer another 5
minutes. If desired, thicken mixture with flour paste (1/4-cup flour
blended in 1/4-cup cold water), and stir frequently. Fill jars with hot
mixture, leaving 1/2-inch headspace. Adjust lids and process.
Process half-pint or pint jars for 20 minutes in a boiling-water bath for
altitudes up to 6,000 feet.
Process jars for 25 minutes for altitudes above 6,000 feet.
Patti Griffith is one of the UW CES
nutrition and food safety educators serving
northwestern Wyoming. She works out
of the UW CES offices in Lander and
Riverton.
Some of the information for this fact
sheet came from newspaper columns by
Cindy Shuster, an extension educator for
The Ohio State University in Perry County,
Ohio, from USDA’s Complete Guide to
Home Canning, from National Center for
Home Food Preservation at http://www.
uga.edu/nchfp, and from the University of
Georgia Cooperative Extension’s So Easy to
Preserve, 5th edition, by Elizabeth Andress
and Judy Harrison. Information about
So Easy to Preserve, which contains many
recipes, and the companion video series
can be found at http://www.uga.edu/setp/.
This recipe is from the National Center for Home Food Preservation.
Editor: Robert Waggener
Graphic Designer: Bernadette van der Vliet
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