Best Food Forward: Smooth stove tops complicate canning

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Do you have a smooth glass or ceramic stove top? Do you plan on preserving foods this season? Heard the rumor that you should use a flat-bottomed canner or just not can on a smooth stove top?

If so you may want to keep reading.

Many smooth-top stoves have a sensor so that the heat won’t go above a certain point and break the top. This sensor does not allow the burner to maintain an even temperature high enough for a canner to work safely. When the temperature fluctuates in the canner, the canning process is shortened; the bacteria are not eliminated, causing the product to be potentially unsafe.

A flat-bottomed canner alone would not solve this problem for all stove tops. If yours has the sensor, the heat will still fluctuate and it won’t get hot enough to get the big canner full of water to a full boil.

If you can confirm with your stove’s manufacturer that a flat-bottomed canner will work, here are some tips to help you.

• The pot must not be more than 1 inch wider that the heating element.

Canners that exceed the burner diameter by more than 1 inch can trap and reflect heat to surfaces of the stove that are not intended to get that hot, and thus crack the stove top. The damage can range from discoloration of white tops, actual burner damage, cracking of the smooth tops, or even fusion of the metal pot to the glass top.

• Avoid dragging.

Scratching of the stove surface can occur if the canner is slid or pulled across the cook top. This often happens with large, heavy filled canners, so people need to be careful.

• Auto-shutoffs prevent sufficient heating.

As mentioned above, many of these cooktops have automatic shut-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 underprocessed and cannot be salvaged as a canned food. The process time must be continuous at the intended temperature, or microorganisms may survive. Also, if the pressure drops quickly, most likely liquid and maybe even food will be lost from the jar.

• Use flat-bottomed canners.

You must use a flat-bottomed canner. Even if boiling-water canning is approved by the manufacturer, it may be necessary to fashion your own canner out of a very large flat-bottomed stockpot with a bottom rack inserted. Many canners are not flat enough to work well on a smooth cooktop and therefore won’t maintain a full boil over the tops of the jars. The pot used as a canner must also be large enough to have plenty of water boiling freely around the jars, and at least 1 to 2 inches over the tops of jars. If the canner is too small, then it starts boiling faster than expected and the total required heat the jars receive in the canner, even before the process time begins, can be too short.

Pressure canning

Most of the manufacturers of pressure canners do not recommend their use on a smooth-top stove. The weight, along with the diameter, prevents them from safe use on a smooth-top stove. There is one brand of pressure canners that does state they are safe for smooth-top stove use. Please, check out the specific pressure canner manufacturers’ recommendations.

Most of all, if you plan to use a smooth-top range for canning, check with the manufacturer for guidelines and follow them. If there are no recommendations, then be cautious.

Don’t forget to call the WSU Food Preservation Hot Line (360-397-6060) if you have any food preservation questions. Master food preservers will answer your call within 24 hours.

Sandra Brown is the food safety and nutrition expert for the Washington State University Cooperative Extension in Clark, Cowlitz and Wahkiakum counties. Reach her at 360-397-6060, ext. 7712 or browns@wsu.edu. The WSU Cooperative Extension in Clark County is at 11104 N.E. 149th St., Building C-100, Brush Prairie, WA 98606.