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Canning fruits and vegetables is a good way to keep fresh produce from going to waste. Oklahoma State University Extension can help consumers test the dial gauge on home pressure canners to make sure it’s accurate, which will help ensure food safety.

OSU Extension checks canning equipment for safety

Tuesday, June 15, 2021

Media Contact: Trisha Gedon | Communications Specialist | 405-744-3625 |

With home gardens ripe for picking and farmers markets bursting with fresh fruits and vegetables, many Oklahomans also are gearing up for canning season.

Canning the bounty from a garden is a great way to get that fresh-picked taste all year long, said Barbara Brown, Oklahoma State University Extension food specialist.

“Canning can help gardeners avoid waste of excess produce by preserving the food for months. However, making sure your canning equipment is in proper working order is essential to help ensure food safety,” Brown said.

Most OSU Extension offices across the state are able to test dial gauges for National, Magic Seal, Maid of Honor and Presto branded pressure canners. The dial gauge is the only part of the canner that needs to be tested to ensure it is in proper working order; the weighted gauges don’t need testing.

To have a gauge tested, contact the nearest local OSU Extension office. If that office does have testing available, bring only the canner lid with the gauge, not the entire canner.

“When tested, if your dial gauge is more than 2 pounds per square inch different — either higher or lower — than the master gauge, it must be replaced to ensure the food canned in that machine is safe to consume,” she said.

The gauge doesn’t need to be tested every time it’s used, but Brown does suggest testing:

  • Before every canning season
  • If the gauge has been submerged in water, dropped or if the glass is broken or missing
  • If any parts are rusty
  • If the pointer isn’t on the “0”
  • If, for any reason, you don’t think the gauge is accurate

Brown also suggested examining the rubber gasket on the canner lid. It should be flexible and soft, not brittle, sticky or cracked.

Gardening interest has increased over the past year partly due to people spending more time at home during the pandemic. It’s a great way to help cut food costs and eat a healthier diet. However, Brown said, home canning can be deadly if proper safety precautions aren’t taken during the canning process.

“About 30% of botulism outbreaks reported to the Centers for Disease Control and Prevention from foods prepared at home were from home-canned vegetables,” she said. “Botulism is a serious illness caused by a germ called Clostridium botulinum, which is found in soil. The germ can multiply and produce toxins in improperly canned food. This is why the first step to safe canning is to make sure your equipment is in proper working order.”

Check with your local OSU Extension office for more food safety tips, or go online to see more of OSU Extension’s food safety information.

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