Canning fruits and vegetables is a way to ensure that you have a variety of produce available, even in the middle of winter, when certain foods might otherwise be hard to find. Almost any kind of fruit or vegetable can be canned, but the appropriate method of preserving them is different for each one.
- High-acid foods, such as most fruits, jellies and pickles, should be canned using a boiling-water canner. The high acid content creates an environment in which bacteria, molds and yeasts do not readily grow, so a boiling-water canner is a safe way to preserve them.
- Low-acid foods, such as most vegetables, stews and meats, should be canned using a pressure canner. A pressure canner preserves food at a much higher temperature than a boiling-water canner, which kills more bacteria, specifically botulinum. If you have a recipe which combines low-acid and high-acid foods, it should be considered a low-acid food.
- To can fruits using a boiling-water canner, you will need, in addition to the canner, home canning jars, lids and bands, a rubber spatula, a timer, a recipe, and a home-canning reference book, such as Ball Blue Book of Preserving. All home-canning guidelines were revised in 1989, so to be safe, don't use recipes published before then.
- Prepare your jars and lids according to your reference book. Keep the jars and lids hot until you're ready to use them, either in a pot of simmering water or in a dishwasher.
- The next step is to prepare your produce. Wash the food thoroughly, then remove the skin if necessary, and wash again. Some fruits, such as peaches and plums, may need to be dipped briefly in boiling water to loosen the skins. Treat the fruit to prevent darkening, using either ascorbic acid or a mixture of lemon juice and water. If the fruit has a pit or seeds, remove them and discard.
- Many fruits will require a sugar syrup. This adds liquid to the fruit to aid the preserving process. The sugar to water ratio of your syrup will vary, depending on whether you want a light or heavy syrup. Your home canning book should provide guidelines for both types of syrup. To prepare a sugar syrup, combine the sugar and water and boil over medium heat, stirring frequently. Continue to boil for at least ten minutes. Keep your syrup hot until you're ready to use it.
- Fruit can be canned using either a cold-pack or hot-pack method. For a cold pack, simply put the fruit into the hot jars, then ladle the sugar syrup over it, leaving the recommended amount of headspace. For a hot pack, heat the fruit in the syrup as directed in your recipe, then spoon it into the jars. Ladle the syrup over the top, just as before.
- Slide a rubber spatula around the inside of the jar to release trapped air, then wipe the top of the jar. Top with a lid, then screw on a band. Tighten the band only to the point of resistance. If you over-tighten the lid, air cannot escape, and a vacuum seal can't be obtained. You also run the risk of breaking the jar.
- Process the jars as directed in your boiling-water canner for the full amount of time indicated in the recipe, to be certain all harmful bacteria and molds are killed. Let the canner cool slightly, then remove the jars and set on a towel on a level surface. Leave the jars for 24 hours, then check for a successful seal. Any jars that didn't seal properly should be reprocessed or refrigerated and used within 48 hours.
- To can vegetables using a pressure-canner, wash the produce well. If necessary, remove skins and seeds. Cut larger vegetables into pieces so that they will fit easily into the jars. Wash the veggies again. Boil the food briefly, anywhere from one minute to five minutes, depending upon your recipe. Spoon the vegetables into your prepared jars, just as above, then add boiling water and a half-teaspoon of salt, if desired. Check to be sure the amount of headspace is correct.
- Remove air bubbles, using a rubber spatula, then wipe the top of the jar with a damp, clean cloth. Place a lid and band on top of the jar and tighten.
- Process the jars as directed in your steam-canner for the recommended amount of time. Allow the canner to cool, then remove jars, let sit for 24 hours and check for a seal.
- Canned produce should be used within one year. When canning, use only produce that is at the peak of ripeness. If you live at a higher altitude, you will need to process your jars for a little longer. Your local extension service can provide guidelines, or you can refer to a website, such as HomeCanning.
After you've tried a few basic canning recipes, get creative! There are many recipes for canning almost everything, including soups and seafood. If you would like to adapt your own recipes for canning, remember to process your food using the ingredient with the longest processing time as a guideline.