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Canning
Ensuring High-Quality Canned Foods
Begin with good-quality fresh foods suitable for canning. Quality varies among varieties of fruits and vegetables. Examine food carefully for freshness and wholesomeness. Discard diseased and moldy food. Trim small diseased lesions or spots from food.
Can fruits and vegetables picked from your garden or purchased from nearby producers when the products are at their peak of quality—within 6 to 12 hours after harvest for most vegetables. For best quality, apricots, nectarines, peaches, pears, and plums should be ripened 1 or more days between harvest and canning. If you must delay the canning of other fresh produce, keep it in a shady, cool place.
Fresh home-slaughtered red meats and poultry should be chilled and canned without delay. Do not can meat from sickly or diseased animals. Ice fish and seafoods after harvest, eviscerate immediately, and can them within 2 days.
Maintaining color and flavor in canned food
To maintain good natural color and flavor in stored canned food, you must:
- Remove oxygen from food tissues and jars,
- Quickly destroy the food enzymes,
- Obtain high jar vacuums and airtight jar seals.
Follow these guidelines to ensure that your canned foods retain optimum colors and flavors during processing and storage:
- Use only high-quality foods which are at the proper maturity and are free of diseases and bruises.
- Use the hot-pack method, especially with acid foods to be processed in boiling water.
- Don't unnecessarily expose prepared foods to air. Can them as soon as possible.
- While preparing a canner load of jars, keep peeled, halved, quartered, sliced, or diced apples, apricots, nectarines, peaches, and pears in a solution of 3 grams (3,000 milligrams) ascorbic acid to 1 gallon of cold water. This procedure is also useful in maintaining the natural color of mushrooms and potatoes, and for preventing stem-end discoloration in cherries and grapes. You can get ascorbic acid in several forms:
Pure powdered form —seasonally available among canners' supplies in supermarkets. One level teaspoon of pure powder weighs about 3 grams. Use 1 teaspoon per gallon of water as a treatment solution.
Vitamin C tablets —economical and available year-round in many stores. Buy 500-milligram tablets; crush and dissolve six tablets per gallon of water as a treatment solution.
Commercially prepared mixes of ascorbic and citric acid —seasonally available among canners' supplies in supermarkets. Sometimes citric acid powder is sold in supermarkets, but it is less effective in controlling discoloration. If you choose to use these products, follow the manufacturer's directions. - Fill hot foods into jars and adjust headspace as specified in recipes.
- Tighten screw bands securely, but if you are especially strong, not as tightly as possible.
- Process and cool jars.
- Store the jars in a relatively cool, dark place, preferably between 50° and 70°F.
- Can no more food than you will use within a year.
Advantages of hot-packing
Many fresh foods contain from 10 percent to more than 30 percent air. How long canned food retains high quality depends on how much air is removed from food before jars are sealed.
Raw-packing is the practice of filling jars tightly with freshly prepared, but unheated food. Such foods, especially fruit, will float in the jars. The entrapped air in and around the food may cause discoloration within 2 to 3 months of storage. Raw-packing is more suitable for vegetables processed in a pressure canner.
Hot-packing is the practice of heating freshly prepared food to boiling, simmering it 2 to 5 minutes, and promptly filling jars loosely with the boiled food. Whether food has been hot-packed or raw-packed, the juice, syrup, or water to be added to the foods should also be heated to boiling before adding it to the jars. This practice helps to remove air from food tissues, shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food permits filling more food into each jar.
Hot-packing is the best way to remove air and is the preferred pack style for foods processed in a boiling-water canner. At first, the color of hot-packed foods may appear no better than that of raw-packed foods, but within a short storage period, both color and flavor of hot-packed foods will be superior.
Controlling headspace
The unfilled space above the food in a jar and below its lid is termed headspace. Directions for canning specify leaving 1/4-inch for jams and jellies, ½-inch for fruits and tomatoes to be processed in boiling water, and from 1- to 1¼-inches in low acid foods to be processed in a pressure canner. This space is needed for expansion of food as jars are processed, and for forming vacuums in cooled jars. The extent of expansion is determined by the air content in the food and by the processing temperature. Air expands greatly when heated to high temperatures; the higher the temperature, the greater the expansion. Foods expand less than air when heated.
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.