Canning and Preserving

When selecting fruit or vegetables for canning, choose the freshest available, preferably picked that day. Going to U-pick farms, farmers' markets or using fruits and vegetables from your own garden is a great way to ensure freshness. Avoid overripe or under-ripe fruits, as that will affect the acidity and stability of the final product. Cucumbers, especially, need to be at their peak of freshness to make great pickles.

Using the proper ratio of sugar, acid and pectin--an essential gelling agent--is critical for jams and jellies, as it determines the texture and flavor of the final product. Pectin is found naturally in many fruits: apples, quince, plums, red and black currants, gooseberries and oranges all contain high pectin levels. Under-ripe fruit contains more pectin than ripe fruit, but is not recommended for preserving due to its lack of flavor. Most recipes call for added pectin, in either liquid or powdered form; there are also special pectins available for making low-sugar preserves. Jams and jellies made without pectin must be cooked longer, depending upon the amount of natural pectin in the fruit. 

(For more recipes, see our Jams, Jellies and Marmalades article.)

Acid is necessary in preserving not only for flavor and texture, but in preventing bacterial growth. In making pickles, acid is an important part of the fermentation process. In fruit preserves, lemon juice is typically used as the acid, while vinegar is more common in vegetable preserves. Preserves made with low-acid foods must be processed in a pressure canner to prevent any bacteria from growing (see Pressure Canning below).

Sterilize your jars by simmering them in a water bath for at least five minutes before using. Jars should remain hot until filled. You may reuse jars and rings from previous years as long as they are in good condition, but new lids must be used each time to ensure a good seal. Inspect the rims of jars for any chips, as these will compromise your seal. Soak the lids in hot water for at least ten minutes to soften the rubber edge. This will help the lids grip the tops of the jars when you screw on the rings. Small jars are preferable, as large jars (over one quart) take longer to process--and since it takes longer for the heat to reach the center of the preserves, the outer layer can become overcooked.

Fill jars nearly to the top. The amount of "headspace" you need depends upon the recipe, so be sure to follow directions. For jams and jellies, it is usually 1/4-inch; fruit preserves and tomatoes need half an inch of headspace, and any low-acid foods that will be processed in a pressure canner will need one inch or more to account for expansion of the contents during processing. Run a thin spatula around the insides of the jars after they have been filled to remove air bubbles, and wipe the rims of the jars with a damp paper towel--any food residue on the rims could prevent a proper seal. Place the warm lids onto the rims and screw the rings into place firmly, but not as tightly as you can. The rubber seal on the lid will be soft from the warm water, so you don't want to crush it out of place. Rings can be tightened further once the jars have cooled.

Processing is the final step in the canning process. This step seals your jars and ensures that the contents are sterile. Most fruits and vegetables can be processed in a hot water bath. The water should cover the lids of the jars by one inch, and should be kept at a low simmer or just below the boiling point. Processing times vary based on acid levels and even your altitude. After processing, as the jars cool, the lids will become sunken in the center and you may hear a little "ping." If you can press down on the center of the lid and make it move, the jar is not properly sealed: refrigerate and consume within two weeks. You can also check the lid and jar rim for imperfections, reseal, and process again within 24 hours.

Foods with low acid levels, such as pumpkin or meats, must be processed in a pressure canner. This method raises the temperature of the water bath and speeds up the process without damaging the food. Pressure canners are not the same as pressure cookers, so don't be tempted to use one! For more processing information, contact your agricultural extension office.

Store your jars away from direct sunlight and in a cool, dry place. Food should be consumed within one year, although many items will not spoil for longer periods. If you see mold, discoloration or smell something off, discard the contents immediately--but don't just trust your nose. Some bacteria can produce toxins that are undetectable by sight or smell, so if a jar's seal has been compromised, throw it away.

Many older canning methods that our grandmothers may have used--such as sealing jars with paraffin wax--have been determined to be unsafe. Every state has an agricultural extension office dedicated to farming, food preservation and other safety issues regarding the home. These are invaluable resources for information on preserving and freezing your harvest. West Virginia even provides community kitchens, so gardeners can do their canning while working with experts to ensure success! Find your local extension on the link to USDA offices or look in the government pages of your phone book.

Does the whole process of canning seem intimidating? Get your feet wet by starting with Freezer Jam or Refrigerator Pickles.