Franklin County

   September 2009
 

Smooth cooktops create problems when canning


Several questions have occurred concerning the safety of canning on smooth cooktops. The National Center for Home Food Preservation recommends owners of smooth cooktops contact the manufacture before attempting to can on any smooth cooktop.

Some manufactures recommend that smooth cooktops not be used for canning at all. Other manufacturers say it is okay to can on them, but put stipulations on the diameter of the canner compared to the diameter of the burner.

First, the cooktop can be damaged by the excessive heat that reflects back down on the surface. This is more likely to occur if the canners used are larger in diameter than is intended for the burner being used. This damage includes discoloration of white tops, actual burner damage, cracking of the glass tops, and/or fusion of the metal to the glass top.

Even if a manufacturer says a burner/cooktop can be used for canning, the cooktop can be scratched if the filled aluminum canner is slid or pulled across the cooktop.

Second, many of these cooktops have automatic cut-offs on their burners when heat gets excessive. If that option is built-in, and the burner under a canner shuts off
during the process time, then the product will be under-processed and cannot be salvaged as a canned food.

If food is not processed at the correct temperature  or correct amount of time,  microorganisms may survive.

Third, many canners do not have flat enough bottoms to work well on a smooth cooktop and still be able to maintain a full boil over the tops of the jars.

One option is to create a canner out of a flat-bottomed stockpot with a bottom rack inserted. The pot must be large enough to allow water to boil freely around the jars, and cover the jars with 2 inches of water.

Before making a decision as to whether or not to can on a smooth cooktop, contact the manufacturer. The manufacture should be able to make recommendations about canning, and may offer up-to-date alternatives or suggestions for suitable equipment for canning.

Clearly state the size  of the  boiling water or pressure canner being used,  how long it must be heated at high heat, how long the hot canner may stay on the burner until it cools after the process time, and that the canner is made from aluminum (if it is).

Source: National Center for Home Food Preservation.  University of Georgia.2006
http://www.uga.edu/nchfp/publications/nchfp/factsheets/smoothtops.html

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