Avoid Open Kettle Canning
Posted: July 5, 2012
Open kettle canning involves heating the food to boiling, pouring it into the jars, applying lids, and allowing the heat of the jar to cause the lid to seal. Many years ago, it was commonly used for pickles, jams and jellies, and sometimes used for juices, tomatoes and applesauce.
The reason open kettle canning is no longer recommended is that the food is not heated adequately to destroy spoilage organisms. Molds and yeasts can enter the jar while you are filling the jar; processing heats the head space of the jar destroying them.
Instead, process jars in a boiling water bath or in a pressure canner to make sure they are adequately heated and to drive air out of the jar and form a strong vacuum seal.
Open kettle canning is not safe! It is especially dangerous when used for canning tomatoes or tomato products where the acid level may be low enough to allow bacterial growth. Never open kettle can low acid foods (meats, vegetables, soups) that should be pressure canned.
Just because a lid “pops,” it doesn’t mean the contents inside the jar are safe. The time saved with open kettle canning is not worth the risk of food spoilage or illness.
Visit the Penn State Food Preservation web site at http://extension.psu.edu/food-safety/food-preservation or call your local Penn State Cooperative Extension office for more home food preservation recipes.