Many of you have been busy preserving the summer's harvest. There is nothing more satisfying than seeing jars of fruits and vegetables on the shelves or a freezer full of neatly organized frozen foods.

There are several extension bulletins available as a resource in preserving foods. The Let's Preserve series of 15 bulletins is available in the Willcox and Sierra Vista offices, as well as the Freezing Fruits and Vegetables and Home Food Drying bulletins.

Several years ago SD and Penn State began intensive research on home food preservation, due to the increasing reports of food poisoning from home canned foods at the Center for Disease Control. There have been several changes in the way USDA and Cooperative Extension teach home canning procedures as a result of the research.

In the article Gifts From the Desert in the September 1992 Master Gardener Newsletter, the procedure for making prickly pear jelly stated, "Pour the liquid into sterilized jelly jars and seal with melted paraffin or cap the jars and put them in the freezer." Due to the research done at Penn State, USDA, and Cooperative Extension, they no longer recommends sealing jelly with paraffin. Boiling water bath canner is recommended for processing jellies, jams, and spreads. For an altitude from 1000 to 6000 feet, process half-pints or pints for 10 minutes. I would like you to note this correction.

Individuals moving into high altitude areas of Arizona often have difficulty using traditional canning recipes. Adjustments in the time and the pressure are necessary when canning food in high altitudes. To use the boiling water bath canner correctly, when processing any food item 20 minutes or less, add 1 extra minute process time for each 1000 feet above sea level. If your instructions require you to process the food item over 20 minutes, add 2 minutes of processing time for every 1000 feet of altitude above sea level.

Low acid food like vegetables, meats and poultry must be heated to 240?F for the appropriate time in order to destroy heat resistant micro-organisms that cause botulism and other types of food spoilage. A pressure canner must be used to obtain a temperature of 240?F. Pressure canners do not destroy micro-organisms, but high temperatures applied for an adequate period of time will. Two serious errors in temperature in pressure canners occur due to the following:

* Air trapped in a pressure canner lowers the temperature obtained at 5, 10, or 15 pounds of pressure and results in under processing of food items. Dial gauge canners do not vent air during processing. To be safe, all types of pressure canners must be vented for 10 minutes before they are pressurized.

* Internal canner temperatures are lower at higher altitudes. To correct this, canners must be operated at increased pressures for appropriate altitude ranges. The rule is to increase canner pressure 1/2 pound for each 1000 feet above sea level.

Home food preservers are asked to upgrade processing times for favorite recipes. USDA and Cooperative Extension encourage home food preserves to the use the new research information to insure a safe food supply.

Another question I am frequently asked is what can be done with jars of canned food which did not seal properly. The food must be refrigerated and used within one or two days. If the food is to be reprocessed, begin at the beginning. Reprocessing food must be done within 24 hours of the original processing. Treat the food as if it were being processed for the first time. There will be changes in texture, color, and possibly flavor. Loss of nutrients may also occur.

If a group would like the lesson UPDATE ON FOOD PRESERVATION, please call me at 384-3594 to schedule the class. This lesson may be adjusted for experienced or beginner home food preservers.