Released August 4, 2008

ST. PAUL, Minn. — It is important to do research before deciding whether or not to use a smooth cooktop for home canning. If we surveyed 10 people about canning on a smooth cooktops we would get 10 different responses with some success stories, but also some horror stories about jars not sealing and damaged cooktops.

The National Center for Home Food Preservation encourages home canners to consider the following issues:

• Smooth cooktop technology varies and can influence how the heat is transferred and maintained. Some manufacturers tell customers not to can on them. Others provide recommendations on the diameter of the canner compared to the diameter of the burner. Some recently designed canners have a curved bottom, so the portion of the canner touching the cooktop is the same diameter as the burner on a smooth cooktop.
• High heat over a long period of time can damage a smooth cooktop because heat is reflected back down on the burner. Damage can vary from cooktop discoloration, burner damage, cooktop cracking or fusion of metal to the glass top. Canning many batches in one day may also damage the heating element or cooktop.
• If a heavy canner is slid or pulled across the surface, the cooktop may be scratched. The scratches may lead to cracking over time.
• Many cooktops have automatic cut-offs when heat gets excessive. If the cooktop burner under a canner shuts off during processing, the product will be under processed and could cause a foodborne illness. Also, if the pressure drops suddenly, liquid and food can siphon out of the jar.
• Many water bath canners do not have flat bottoms and it can be difficult to maintain a full boil during processing. It may be possible to use a flat-bottomed stockpot with a bottom rack to hold jars if there is at least 1 inch of water over the tops of the jars.

Before making a decision to can on a smooth cooktop, contact the cooktop manufacturer. Do not rely only on the advice of an appliance salesperson. Today’s manufactures know their cooktops and may have suggestions. When visiting with the manufacturer, explain what you will be doing, describe the canner size, what the canner is made from and how long the canner will be on the burner.

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http://www.extension.umn.edu/extensionnews/2008/canningonsmoothcooktop.html

Contacts: Carol Ann Burtness is a food science educator with University of Minnesota Extension.

Catherine Dehdashti, (612) 625-0237, ced@umn.edu