To preserve foods by canning two things must be done. First, sufficient heat must be provided to destroy all microscopic life that will cause spoilage in food; and second a perfect seal must be made which will prevent the re-entrance of microorganisms. These problems of preventing spoilage have been practically solved by the improved methods of canning which are explained below.
Only the freshest of fruits and vegetables should be canned. Canning does not improve the taste of the product; it only preserves it for future use.
Methods of Canning
Open Kettle: This method involves cooking the product completely and pouring it into sterilized jars, using sterilized equipment throughout. The jars are then sealed and stored. The open kettle method is recommended only for preserves, pickles, and foods canned in thick syrup. For other foods use the following methods.
Cold Pack: Cold, raw foods are put into jars and covered with boiling-hot syrup, juice of water. (Tomatoes are pressed down in the jar so they are covered with their own juice.) Jars are partially or completely sealed, following manufactures directions. Jars are then processed in boiling water or in steam to simultaneously cook the food and sterilize the jars.
Hot Pack: Fruits and vegetables are preheated before packing causing shrinkage before food goes into jars. This is the preferred method as preheating the food before packing prevents “floating”, (especially with fruits) and assures a full pack. Processing time is also lessened when food is hot-packed.