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Canning

Storing Home Canned Foods

These three options are for two-piece metal lid system with a flat lid and a ring band.  If you use another type, follow the manufacturer's directions for determining if jars are vacuum sealed.

After cooling jars for 12 to 24 hours, remove the ring bands and test seals with one of the following options:

Option 1: Press the middle of the lid with a finger or thumb. If the lid springs up when you release your finger, the lid is unsealed.

Option 2: Tap the lid with the bottom of a teaspoon. If it makes a dull sound, the lid is not sealed. If food is in contact with the underside of the lid, it will also cause a dull sound. If the jar is sealed correctly, it will make a ringing, high-pitched sound.

Option 3: Hold the jar at eye level and look across the lid. The lid should be concave (curved down slightly in the center). If center of the lid is either flat or bulging, it may not be sealed.

Reprocessing Unsealed Jars

Sometimes a jar in a canner load fails to seal upon cooling. This may happen because of a cracked or nicked jar, or perhaps because food is fouling the jar rim where the lid sits. Due to loss of quality, reprocessing of jars is not recommended.

If you do reprocess, follow these steps for a safe product:

1. Re-process within 24 hours. For a safe final product, you must have followed an up-to-date research-tested recipe on your first attempt, and you must reprocess within 24 hours.

2. Remove the lid and empty the contents of the jar into a large pot and heat to boiling.

3. Fill a clean jar with the heated food, remove air bubbles, and top with a new lid.

4. Reprocess using a tested recipe for a hot-pack product.  If there is no tested hot-pack recipe, the product may not be safely reprocessed.

If you did not follow a tested recipe on the first try, all jars, sealed or unsealed, may be unsafe and should be discarded. 

To preserve quality of food where jars failed to seal (and discovered within 24 hours of initial canning), refrigerate the jars and consume contents within one week. Unsealed jars may also be frozen for up to one year, be sure to adjust headspace to 1” before freezing.

Storing Canned Foods

If lids are tightly vacuum sealed on cooled jars, remove ring bands, wash the lid and jar to remove food residue without disturbing the sealed lid; then rinse and dry jars. There may be food or syrup residues you might not notice with your eye.  These residues can support the growth of molds (which are airborne) outside the jar during storage. Wash and dry ring bands to protect them from corrosion for future use; be sure to protect from moisture where they are kept. It is recommended that jars be stored without ring bands to keep them dry as well as to allow for easier detection of any broken vacuum seals. However, if you choose to re-apply the ring bands, make sure all surfaces are clean and thoroughly dry first.

If jars are stacked in storage, be careful not to disturb vacuum seals. It would be a good idea to not stack jars too high directly on top of each other; one manufacturer recommends no more than two layers high. It would be best to provide support between the layers as a preventive measure against disturbing the seals on the lower jars. Jars could be placed in boxes to be stacked, or use some type of a firm solid material across the jars as a supportive layer in between them.

Label and date the jars and store them in a clean, cool, dark, dry place. For best quality, store between 50 and 70 °F. Also for best quality, can no more food than you will use within a year unless directions for a specific food provide other advice.

Do not store jars above 95° F or near hot pipes, a range, a furnace, in an uninsulated attic, or in direct sunlight. Under these conditions, food will lose quality in a few weeks or months and may spoil. Dampness may corrode metal lids, break seals, and allow recontamination and spoilage.

Accidental freezing of canned foods will not cause spoilage unless jars become unsealed and recontaminated. However, freezing and thawing may soften food. If jars must be stored where they may freeze, wrap them in newspapers, place them in heavy cartons, and cover with more newspapers and blankets.

Identifying and Handling Spoiled Canned Food

Do not taste food from a jar with an unsealed lid or food that shows signs of spoilage. You can more easily detect some types of spoilage in jars stored without screw bands. Growth of spoilage bacteria and yeast produces gas which pressurizes the food, swells lids, and breaks jar seals. As each stored jar is selected for use, examine its lid for tightness and vacuum. Lids with concave centers have good seals.

Next, while holding the jar upright at eye level, rotate the jar and examine its outside surface for streaks of dried food originating at the top of the jar. Look at the contents for rising air bubbles and unnatural color.

While opening the jar, smell for unnatural odors and look for spurting liquid and cotton-like mold growth (white, blue, black, or green) on the top food surface and underside of lid.

Spoiled low-acid foods, including tomatoes, may exhibit different kinds of spoilage evidence or very little evidence. Therefore, all suspect containers of spoiled low-acid foods, including tomatoes, should be treated as having produced botulinum toxin and handled carefully in one of two ways:

  • If the swollen metal cans or suspect glass jars are still sealed, place them in a heavy garbage bag. Close and place the bag in a regular trash container or dispose in a nearby landfill.
  • If the suspect cans or glass jars are unsealed, open, or leaking, they should be detoxified before disposal.

Detoxification process: Wear disposable rubber or heavy plastic gloves. Carefully place the suspect containers and lids on their sides in an 8-quart volume or larger stock pot, pan, or boiling-water canner. Wash your hands with gloves thoroughly. Carefully add water to the pot and avoid splashing the water. The water should completely cover the containers with a minimum of a 1-inch level above the containers. Place a lid on the pot and heat the water to boiling. Boil 30 minutes to ensure detoxifying the food and all container components. Cool and discard the containers, their lids, and food in the trash or dispose in a nearby landfill.

Cleaning up the area: Contact with botulinum toxin can be fatal whether it is ingested or enters through the skin. Take care to avoid contact with suspect foods or liquids. Wear rubber or heavy plastic gloves when handling suspect foods or cleaning up contaminated work surfaces and equipment. A fresh solution of 1 part unscented liquid household chlorine bleach (5 to 6% sodium hypochlorite) to 5 parts clean water should be used to treat work surfaces, equipment, or other items, including can openers and clothing, that may have come in contact with suspect foods or liquids. Spray or wet contaminated surfaces with the bleach solution and let stand for 30 minutes. Wearing gloves, wipe up treated spills with paper towels being careful to minimize the spread of contamination. Dispose of these paper towels by placing them in a plastic bag before putting them in the trash. Next, apply the bleach solution to all surfaces and equipment again, and let stand for 30 minutes and rinse. As a last step, thoroughly wash all detoxified counters, containers, equipment, clothing, etc. Discard gloves when cleaning process is complete. (Note: Bleach is an irritant itself and should not be inhaled or allowed to come in contact with the skin.)

 

Adapted from the "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, USDA (Revised 2015), Guide 1, pp. 1-25 to 1-27, and "So Easy to Preserve", 6th ed., p. 34.

Recent Content

Can Splenda® (sucralose) be used in preserving food?

Granular Splenda® does not provide preservative properties like sugar. 

Canning Fruits:  Whereas we do not have published research work with using sucralose in the canning of fruits at home available to us, it is possible to use it for sweetening the water used to cover fruits when canning.  The texture and color preserving aspects of a sugar syrup will not be provided.  The result would be like canning in water except for the additional sweetness contributed by the Splenda®.  The USDA fruit canning directions do allow for canning in water (i.e., without a sugar syrup), as there is adequate preservation for safety from the heat of proper canning.  Some people do notice an aftertaste in other products and canned fruits, and it is possible some little changes in natural flavors may occur over storage time, since sugar can mask some of these.  For people used to sucralose sweetening and flavors, the aftertaste may not be an issue.  Based on some of our experiences in canning peaches and pickled foods, we suggest you start seeing what you like by trying less than a full substitution for the sugar in canning syrups.  For example, if you use a medium sugar syrup that is 5-/14 cups water to 2-1/4 cups sugar, try 1 to 1-1/4 cups Splenda® the first time.  You can always sweeten more when you serve the finished product if it is not quite sweet enough; then you can increase the canning liquid amount the next time you can.

Preserves and Pickled Fruits: In other cases, where sugar is important, like some preserves or pickled fruits, it is not recommended that substitution of Splenda® be used for sugar if the product is to be canned for shelf stability.  Splenda® cannot be used in several traditional Southern preserves we have on this website or in the University of Georgia Extension publications.  These are whole or uniform pieces of fruit in a very thick sugar syrup, usually made with figs, peaches or pears.  (These preserves are not jam or pectin gel products.)  Sugar is required for the preservation of these syrupy fruit preserves as published, with very short boiling water canner processes.  Without that heavy amount of sugar, these products become fruit pieces canned in water or lighter sugar syrups, and the usual (and longer) fruit canning process times and preparation directions would need to be used.

Jams and Jellies, or Fruit Spreads: You could use Splenda® as the optional sweetener in a jam or jelly made with a no-sugar needed pectin, such as Mrs. Wages™ Lite Home Jell® Fruit Pectin, Ball® No-Sugar Needed Pectin or Sure-Jell® for Less or No-Sugar-Needed Recipes.  With these low-methoxyl pectins, no sugar is required at all.  Sugar substitutes can be added as desired simply for flavor. The package inserts with these pectins give instructions on when to add the sugar substitutes (usually after all the cooking, right before filling the jars).  Do not try to substitute Splenda® for the required sugar in recipes calling for “regular” liquid and powdered pectins.  

And do not try to substitute Splenda® in long-boil or no-pectin-added jams and jellies intended for room temperature storage as a canned product.  You might get some thickened fruit spreads with just fruit and Splenda®, but they may not have enough water control for processing like a gelled, high sugar-containing jam or jelly.  They might require longer processing to avoid spoilage at room temperature.  If you want to experiment with making these kind of fruit spreads we recommend freezing or refrigeration for storage. 

We have developed three recipes using Splenda® and they are on our website, www.homefoodpreservation.com. They are quick pickled sweet cucumber slices, pickled beets and pickled cantaloupe.  They are under the How do I....Pickle category, as well as National Center factsheets, http://www.uga.edu/nchfp/publications/nchfp/factsheets.html.

There is also a Peach-Pineapple Reduced Sugar Fruit Spread from the USDA Complete Guide to Home Canning that does not require added sugar.  Some other fruit substitutions are provided in the text.  The suggested sugar for sweetening can be left out, or you can add some Splenda® as desired for sweetness.  The process time is longer than regular jams and jellies, and is like that for a fruit puree. http://www.uga.edu/nchfp/how/can_07/peach_pineapple_spread.html

How can I become a Master Food Preserver?

“Master” volunteer programs that are connected to the Cooperative Extension System, such as Master Food Preservers and Master Gardeners, are currently state- or county-managed programs affiliated with the land grant universities and the Cooperative Extension Service in the state. In exchange for extensive education, the master volunteer returns contributions to the local Extension office, such as answering phone calls, developing and hosting exhibits, judging at competitions, etc. There are liabilities involved in someone conducting even volunteer work in the name of a state university; therefore, the guidelines and management procedures will vary among states. At this time, the National Center is not in a position to help individuals meet state guidelines for credentials and the title of Master Food Preserver.

If you would like to find out if your state offers this opportunity to become a Master Food Preserver, contact your local Extension Office (usually listed in local government pages of the phone book under Cooperative Extension Service, Ag Extension Office and/or 4-H Office). You could also contact someone at the state university to either ask your questions or let them know of your interest. These contacts can be found on a website managed by USDA:
https://nifa.usda.gov/nutrition-and-food-safety-directory

Most states do not sell their Master Food Preserver curricula or notebooks to the general public. If someone wants information on preserving, they have other publications available with the actual recommendations and procedures. This website from the National Center is full of “How To” information for various types of food preservation. We will eventually have tutorials and a correspondence type course on line for self-study.

Is it necessary to thaw meat or fish before cooking?

No, meat and fish can be cooked from the frozen state if extra cooking time is allowed. The amount of time will depend on the size and shape of the cut. Large frozen roasts can take as much as 11/2 times as long to cook as unfrozen cuts of the same weight and shape. Small roasts and thin cuts such as steaks and chops require less time.

Can meat and poultry be thawed in the conventional oven?

No, meat and poultry should never be thawed in the conventional oven or at room temperature. There is greater danger of bacterial growth and food spoilage for food thawed at room temperature. Thaw meat and poultry in the refrigerator in the original wrappings. To speed thawing, loosen the wrapping. To keep other foods safe, put the thawing meat and poultry in a pan on the bottom shelf. For a quicker method, immerse meat or poultry in a watertight bag into cold water. Thaw until it is pliable. Meat and poultry can also be thawed quickly and safely in the microwave oven, followed by immediate cooking, either in the microwave oven or by some other method. Because microwave ovens vary, check your manufacturer's instructions for information on how to safely thaw in your microwave oven. Frozen meat and poultry can also be cooked without thawing.

What is blanching?

Heating or scalding the vegetables in boiling water or steam for a short period of time.

Is it recommended to blanch vegetables before freezing?

Yes. Blanching slows or stops the action of enzymes which cause loss of flavor, color and texture. Blanching cleanses the surface of dirt and organisms, brightens the color and helps retard loss of vitamins. Blanching also wilts or softens vegetables and makes them easier to pack.

Is it safe to freeze fruits without sugar?

Yes; sugar is not used as a preservative but only to maintain flavor, color and texture.

Can artificial sweeteners be used in place of sugar for freezing fruits?

Sugar substitutes can be used in place of sugar. Labels on the products give the equivalents to a standard amount of sugar. Follow the directions to determine the amount of sweetener needed. Artificial sweeteners give a sweet flavor but do not furnish beneficial effects of sugar, like thickness of syrup and color protection.

SO EASY TO PRESERVE

The University of Georgia Cooperative Extension has now published a 6th edition of its popular book, So Easy To Preserve. The book was reviewed and updated in 2020. Chapters in the 388-page book include Preserving Food, Canning, Pickled Products, Sweet Spreads and Syrups, Freezing and Drying.