Understanding how to prevent food spoilage and deterioration is the key to canning safety and success. In the air and all around us are invisible microorganisms, such as molds, yeasts and bacteria. Many of these microorganisms are beneficial to us, while others can be harmful under certain conditions. These “spoilers” live and multiply on the surface of fruits, vegetables, meats and all other types of food. Foods affected by bruising, insect damage and disease are more likely to have greater levels of microorganisms associated with spoilage. Enzymes change the color, texture and flavor of food and are found throughout the tissue of each food type. If enzyme activity goes unchecked, food quality will deteriorate. Molds, yeasts, bacteria and enzymes are the major causes of food spoilage and loss of quality.
Controlling the conditions which encourage the growth of molds, yeasts, bacteria and enzymes is an important factor in controlling spoilage and decaying. Washing foods is helpful in removing some of the spoilage microorganisms. Peeling and blanching reduces even greater numbers of spoilage microorganisms. Blanching is also a good way to minimize the effects of enzyme activity.
Canning interrupts the normal spoilage and decaying cycle of food by heating the food contained in a home canning jar that has been closed with a two-piece vacuum sealing cap. When heat is applied at the correct temperature and held there for the time designated by a specific tested home canning recipe, it destroys potentially harmful microorganisms; at the same time, it drives air from the jar. Upon cooling, the lid seals onto the jar. The vacuum that has formed prevents other microorganisms from entering and contaminating the food. This procedure is also known as processing. Correct processing methods and times adequately destroy normal levels of heat-resistant microorganisms. Proper storage and handling of sealed jars also helps ensure that home canned foods will be free of spoilage.
*Adopted from Ball Blue Book® Guide to Preserving