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Canning

Recommended Jars and Lids

Food may be canned in glass jars or metal containers. Metal containers can be used only once. They require special sealing equipment and are much more costly than jars.

Regular and wide-mouth Mason-type, threaded, home-canning jars with self-sealing lids are the best choice. They are available in ½ pint, pint, 1½ pint, quart, and ½ gallon sizes. The standard jar mouth opening is about 2-3/8 inches. Wide-mouth jars have openings of about 3 inches, making them more easily filled and emptied. Half-gallon jars may be used for canning very acid juices. Regular-mouth decorator jelly jars are available in 8 and 12 ounce sizes. With careful use and handling, Mason jars may be reused many times, requiring only new lids each time. When jars and lids are used properly, jar seals and vacuums are excellent and jar breakage is rare.

Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods. However, you should expect more seal failures and jar breakage. These jars have a narrower sealing surface and are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. Seemingly insignificant scratches in glass may cause cracking and breakage while processing jars in a canner. Mayonnaise-type jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for use in canning any food at home.

Jar Cleaning

Before every use, wash empty jars in hot water with detergent and rinse well by hand, or wash in a dishwasher. Unrinsed detergents may cause unnatural flavors and colors. These washing methods do not sterilize jars. Scale or hard-water films on jars are easily removed by soaking jars several hours in a solution containing 1 cup of vinegar (5 percent acidity) per gallon of water.

Sterilization of Empty Jars

All jams, jellies, and pickled products processed less than 10 minutes should be filled into sterile empty jars. To sterilize empty jars, put them right side up on the rack in a boiling-water canner. Fill the canner and jars with hot (not boiling) water to 1 inch above the tops of the jars. Boil 10 minutes at elevations of less than 1,000 ft. At higher elevations, boil 1 additional minute for each additional 1,000 ft elevation. Remove and drain hot sterilized jars one at a time. Save the hot water for processing filled jars. Fill jars with food, add lids, and tighten screw bands.

Empty jars used for vegetables, meats, and fruits to be processed in a pressure canner need not be presterilized. It is also unnecessary to presterilize jars for fruits, tomatoes, and pickled or fermented foods that will be processed 10 minutes or longer in a boiling-water canner.

Lid Selection, Preparation, and Use

The common self-sealing lid consists of a flat metal lid held in place by a metal screw band during processing. The flat lid is crimped around its bottom edge to form a trough, which is filled with a colored gasket compound. When jars are processed, the lid gasket softens and flows slightly to cover the jar-sealing surface, yet allows air to escape from the jar. The gasket then forms an airtight seal as the jar cools. Gaskets in unused lids work well for at least 5 years from date of manufacture. The gasket compound in older unused lids may fail to seal on jars.

Buy only the quantity of lids you will use in a year. To ensure a good seal, carefully follow the manufacturer's directions in preparing lids for use. Examine all metal lids carefully. Do not use old, dented, or deformed lids, or lids with gaps or other defects in the sealing gasket.

When directions say to fill jars and adjust lids, use the following procedures: After filling jars with food and adding covering liquid, release air bubbles by inserting a flat plastic (not metal) spatula between the food and the jar. Slowly turn the jar and move the spatula up and down to allow air bubbles to escape. (It is not necessary to release air bubbles when filling jams, jellies or all liquid foods such as juices.) Adjust the headspace and then clean the jar rim (sealing surface) with a dampened paper towel. Place the preheated lid, gasket down, onto the cleaned jar-sealing surface. Uncleaned jar-sealing surfaces may cause seal failures. Then fit the metal screw band over the flat lid. Follow the manufacturer’s guidelines enclosed with or on the box for tightening the jar lids properly.

Do not retighten lids after processing jars. As jars cool, the contents in the jar contract, pulling the self-sealing lid firmly against the jar to form a high vacuum.

  • If rings are too loose, liquid may escape from jars during processing, and seals may fail.
  • If rings are too tight, air cannot vent during processing, and food will discolor during storage. Over tightening also may cause lids to buckle and jars to break, especially with raw-packed, pressure-processed food.

Screw bands are not needed on stored jars. They can be removed easily after jars are cooled. When removed, washed, dried, and stored in a dry area, screw bands may be used many times. If left on stored jars, they become difficult to remove, often rust, and may not work properly again.

 

This document was extracted from the "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, USDA (Revised 2015).

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.