Gardens and farmers markets are overflowing with delicious summer vegetables. Why not save some vegetables and fruits for the months ahead? Unless foods are preserved, microorganisms such as mold, yeast and bacteria will cause spoilage soon after harvesting. The three main methods of preserving foods are canning, freezing and drying.
Canning is the method of packing jars and processing to a temperature that destroys microorganisms. Processing kills bacteria, yeasts and molds that can cause food spoilage and food-borne illness. Processing can be done in a water bath canner or a pressure canner, depending on the acidity level in the food. Acid foods such as fruits and tomatoes can be canned in boiling water, while low acid vegetables and meats must be processed in a pressure canner at 11 pounds pressure for a dial gauge or 10 pounds for a weighted gauge.
1. Use only standard canning jars. Other commercial jars are not resistant to temperature extremes that may cause breakage. Check all jars for cracks, chips or nicks on the top edge. Any flaw could cause breakage or prevent sealing.
2. Wash canning jars in a dishwasher or in hot soapy water and rinse well. Keep jars hot in the dishwasher or hot water until ready to fill them.
3. Only use a two piece canning lid. The set is a flat metal lid and a screw on band. The sealing compound on the flat lid will form the vacuum seal needed during cooling of the jars. The bands may be cleaned and dried after use and be reused in future canning. Never reuse a metal lid.
4. A water bath canner is a large deep kettle with a lid and a rack to hold jars. Fill with water to 1-2 inches above the jars for processing. Use a water bath canner to process acid foods such as fruit, acidified tomatoes, and properly pickled vegetables.
5. A pressure canner is used to process low acid foods including meats, seafood, poultry, and all vegetables. A pressure canner has a tight-fitting lid with a gasket and a pressure gauge. A weighted gauge fits over the air vent tube. It permits pressure in the canner to rise to the desired point and then releases excess steam by jiggling. Check the vent tube to be sure it hasn’t been bent or damaged during use. A dial gauge has a needle that moves along a numbered scale to indicate the pressure inside the canner. Each year check with your FCS agent at the NC Cooperative Extension in Yadkinville at 679-2061, for a dial gauge check to be sure of accuracy.
6. Select high quality, unblemished fruits and vegetables for canning. Pack acid foods to within a half inch of the top of the jar. Low acid foods should be packed to within 1 inch of the top of the jar. Fill the remaining space in the jar with water or juice. Wipe the jar rims clean, put on the lid with the sealing compound next to the jar rim, and screw the band down firmly so that it is hand-tight. Do not use a jar wrench to tighten bands! If the band is too tight the lid may buckle under pressure. There must be enough give for air to escape from the jars during processing.
7. Because many new varieties of tomatoes have a variety of ph values, it is now recommended to add acid to the canning process whether you use boiling water bath or a pressure canner. To insure the correct acidity, add 1 tablespoon of bottled lemon juice or 1/4 teaspoon citric acid or 2 tablespoons vinegar per pint. For quarts, add 2 tablespoons bottled lemon juice, 1/2 teaspoon citric acid or 4 tablespoons of vinegar to each jar.
8. Read the manufacturer’s instructions for use of your pressure canner. Center canner over the burner and heat on high. Heat until the water boils and steam flows freely from the vent port for 10 minutes. After the venting, place the counter weight or weighted gauge on the ventport. For a dial gauge canner allow the pressure to rise to 8 lb. and then turn the burner down slightly for the pressure to continue to rise slowly. For weighted gauge canners, let the canner heat quickly until steam begins to escape from the gauge, or the gauge moves and jiggles. Adjust the heat down slightly. Start timing when the dial gauge indicates that the recommended 11 lb. pressure is reached or when the weighted gauge begins to jiggle or rock 2-3 times per minute. Adjust the heat under the canner to maintain a steady pressure. When the amount of processing time is reached, cut off the burner and allow the canner to cool down naturally. It is very dangerous to try to open the canner before the pressure is completely down, wait 10 minutes before carefully opening the lid. Using a jar lifter, place jars on towels or a cake rack for cooling. Do not remove the bands or disturb the jars for 12 to 24 hours. Enjoy the popping sounds of the jars as they seal!
9. Carefully follow processing directions from research based materials obtained from the NC Cooperative Extension office, Marilyn_Wells@ncsu.edu, the Ball Blue Book, the National Institute of Food Preservation, or www.soeasytopreserve.com. For further information call Marilyn Wells at the Yadkin Center, NC Cooperative Extension office at 679-2061.