Preserving food for future use is a practical way to stretch food dollars and prepare for emergencies, such as hurricanes or extended power outages. The three primary methods for preserving food are canning, freezing, and drying.
Canning is the process in which foods are placed in jars or cans and heated to a temperature that destroys microorganisms and inactivates enzymes. The heating and later cooling forms a vacuum seal. The vacuum seal prevents other microorganisms from recontaminating the food within the jar or can. Acid foods, such as fruits and tomatoes, can be processed or “canned” in boiling water, while low acid vegetables and meats must be processed in a pressure canner at 240 degrees F (10 pounds pressure at sea level).
Freezing reduces the temperature of the food so that microorganisms cannot grow, however, many will survive. Enzyme activity is slowed down but not stopped during freezing.
Drying removes most of the moisture from foods. Thus microorganisms cannot grow and enzyme action is slowed down. Dried foods should be stored in airtight containers to prevent moisture from rehydrating the products and allowing microbial growth.
Click here for the latest USDA canning guidelines.
Click here for the latest USDA freezing guidelines.
Click here for the latest USDA drying guidelines.