Processing is essential to ensure safety when canning fruits. Because fruits are acidic, the boiling water bath method may be used for processing. Although spoilage can occur in home-canned fruits, contamination with Clostridium botulinum, the bacteria that causes botulism, is not a threat.However, some people prefer to pressure-process fruits. This is also an acceptable method.

Organisms that cause food spoilage — molds, yeasts and bacteria — are always present in the air, water and soil. Also, enzymes that may cause undesirable changes in flavor, color and texture are present in raw fruits. Use recommended processing methods and times when canning fruits to destroy spoilage organisms and stop the action of enzymes.

General canning procedures

Jars and Lids

Mason-type canning jars are the best choice. The standard jar mouth is about 2-3/8 inches. Widemouth 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 only.

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 may expect more sealing failures and jar breakage. These jars have a narrower sealing surface and are tempered less than Mason jars. Mayonnaise-type jars are not recommended for use with foods that will be processed in the pressure canner. Use two-piece self-sealing lids. Buy only the quantity of lids that will be used in a year and follow the manufacturer’s directions for preparing the lids.

Sterilize 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 altitudes of less than 1,000 feet. At higher elevations, boil one additional minute for each additional 1,000 feet elevation. Remove and drain hot sterilized jars one at a time just before filling. Save the hot water for processing filled jars. Fill jars with food, apply lids, and tighten screw bands. It is unnecessary to presterilize jars for fruits that will be processed 10 minutes or longer in a boiling water canner.

Filling Jars

After filling jars with food, 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. Adjust the headspace and then clean the jar rim (sealing surface) with a dampened paper towel. Place the 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.

Prevent Darkening

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 ascorbic acid. This procedure is also useful 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 three grams. Use one 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.
* Store the jars in a relatively cool, dark place, preferably between 50 degrees and 70 degrees Fahrenheit.
* Can no more food than you will use within a year.

Sweetening Fruit

Adding syrup to canned fruit helps to retain its flavor, color and shape. It does not prevent spoilage of these foods. The guidelines in Table 1 for preparing and using syrups offer a new “very light” syrup, which approximates the natural sugar content of many fruits. Quantities of water and sugar to make enough syrup for a canner load of pints or quarts are provided for each syrup type.

Procedure: Heat water and sugar together. Bring to a boil and pour over raw fruits in jars. For hot packs, bring water and sugar to boil, add fruit, reheat to boil, and fill into jars immediately.

Other sweeteners: Light corn syrups or mild-flavored honey may be used to replace up to half the table sugar called for in syrups.

For more information visit http://www.ag.ndsu.edu/pubs/yf/foods/he174w.htm