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Are Canners Passed Down for Generations Really Safe


My grandmother used to give me a case of quart size, home canned green beans. I never realized the labor of love that they were until I started canning myself. To me there is nothing as beautiful as a jar of home canned produce.

Although I do not have my grandmothers pressure canner, many canners are passed down or bought at estate sales or yard sales. While there is definitely nothing wrong with that, it is important that the pressure canner be working properly.

How do I know if my canner is safe?

The only way to know that is to have it tested to ensure the safety of the food being processed.

If your canner isn’t working properly the foods in the jar can be under-processed, which even in a pressure canner, can increase the chance that botulism spores may still be present in the jars!

How do I get my canner tested?

County Extension Family Consumer Science educators are available to test consumers dial gauge pressure canners to determine accuracy of the gauge. Dial gauges should be tested annually to assure that the pressure indicated on the dial is accurate.

Pressure gauge testing is only done by appointment and only certain pressure cookers can be tested.

Call your local county extension office to get an appointment and to check if your canner is a type we test. There is no charge for this service.

Pressure canning is the only recommended method for canning meat, poultry, seafood, and low acid vegetables.

Pressure canners destroy the bacterium Clostridium Botulinum which can be found in low-acid foods when they are processed at the correct time and pressure in pressure canners.

If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal. Using boiling water bath canners when a pressure canner is intended will pose an increased real risk of botulism poisoning.

Pressure canners for use in the home have been extensively redesigned in recent years.

Models made before the 1970’s were heavy-walled kettles with clamp-on or turn-on lids. They were fitted with a dial gauge, a vent port in the form of a petcock or counterweight, and a safety fuse.

Modern pressure canners are lightweight, thin walled kettles; most have turn-on lids. The older models are still safe, as long as the dial is accurate, they are just heavier.

Newer models will have a jar rack, gasket, dial or weighted gauge, an automatic vent/cover lock, a vent port (steam vent) to be closed with a counterweight or weighted gauge, and a safety fuse.

Pressure does not destroy microorganisms, but high temperatures applied for an adequate period of time do kill microorganisms. The success of destroying all microorganisms capable of growing in canned food is based on the temperature obtained in pure steam, free of air. A canner operated at a gauge pressure of 10.5 pounds of pressure provides an internal temperature of 240°F.

Green beans and tomatoes are among the most popular vegetables for home canning. Because of their low acidity, vegetables such as green beans must be processed in a pressure canner.

We also have the newest edition of So Easy to Preserve for sale in our office as well as free publications with updated U.S. Department of Agriculture recommendations for home canning. If your home canning recipes are older than 5 years old, it is time to come get new ones with the latest recommendations.

Contact your local county Extension office for recipes.


By Carla Due
County Extension Agent - FCS
U of A Division of Agriculture
Cooperative Extension Service
400 Laurel Street, Suite 215 Texarkana AR 71854
(870) 779-3609

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