The produce from your garden and from local farmers' markets and roadside stands is ripe for the picking.  Enjoying fresh produce this time of year is easy.  Enjoying it all year long is possible by preserving this bounty for later months.

Canning, freezing, and drying are the three main mehods of home food preservation.  The availability of safe guidlines for a prticular food helps determine which method best suits your needs.

Canning is the process by which foods are placed in jars and heated to a temperature that destroys microorganisms and inactivates enzymes.  Canning can be a safe and economical way to preserve food at home, but make sure that the proper method is used for each item, that the equipment is used correctly, and that recipes tested for safety are carefully followed. 

Whether food should be processed in a pressure canner or boiling water canner to control Clostridium botulinum (the bacteria that can lead to botulism) depends on the acidity of the food.

The term "pH" is a measure of acidity; the lower the pH value, the more acidic the food is.  Acidity may be an inherent part of the food, as with most fruits, or added, as in pickled foods.

Foods high in acid contain adequate acid to prevent the growth of Clostridium botulinum.  Low-acid foods do not contain enough acid to prevent the growth of this organism and must be processed with a pressure canner.

The acidity level in foods can be increased by adding lemon juice, citric acid, or vinegar.  Acidic foods such as fruits do not support the outgrowth of Clostridium botulinum and can be processed, or canned, in boiling water.

These foods include all fruits, acidified tomatoes, sauerkraut, pickles, and relishes.  If tomato products are acidified, they can be safely processed in a water bath canner.  If not, they must be processed in a pressure canner.  Jams, jellies, and preserves are also processed in a boiling water bath.

Low-acid vegetables must be processed at a temperatire of 240 degrees F, which can be reached inside a pressure canner.  These inlude all vegetables, except acidified tomatoes.  These foods contain very little natural acid.

Mixtures that contain both high-acid and low-acid foods must also be canned in a pressure canner.  An example of such a mixture is okra and tomatoes.  Failure to follow these guidelines could cause botulism, a life-threatening food-borne illness.

In our area, process foods in a weighted gauge pressure canner at 10 pounds pressure.  If you are using a dial gauge presure canner, use 11 pounds of pressure.  In addition, the correct amount of time needed to destroy bacteria must be part of the process.

The time ranges from 20 to 100 minutes.  The exact time depends on the kind of food being canned, the way it is packed into the jars, and the size of the jars.  Never guess at the length of time to process food.  Cutting the time short can be dangerous.

Other unsafe canning methods include open kettle, oven canning, canning in the dishwasher, adding aspirin, steam canners and microwave oven canners. 

Sources for research-based canning recipes and instructions include:  The National Center for Home Food Preservation at www.uga.edu/nchfp, So Easy to Preserve, Fifth Edition, Cooperative Extension Service, The University of Georgia, 2006, and the U.S. Department of Agriculture, (USDA) Complete Guide to Home Canning, 2006 Revision.