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Heirloom Canners May Not Be Safe

Before you begin this year's canning season, you need to make sure everything is in working order.

Nashville, Ark. – Canning season is right around the corner. Nothing is prettier than seeing a row of fresh canned vegetables sitting on the shelf of your pantry. It is a labor of love to spend the time and effort it takes to home can your produce. However, nothing tastes better than opening that jar of green beans on a cold winter’s night. They taste just like they were picked.

            Before you begin this year’s canning season, you need to take inventory of your canning supplies and make sure everything is in working order. This includes the pressure canner. Pressure canners are an initial investment. Since they can be expensive, many families pass down their canner to younger family members. Or you may find one, fairly inexpensive, at a garage sale and decide to pick it up. While there is definitely nothing wrong with that, it is important that the pressure canner be working properly. The only way to know that is to have it tested to ensure the safety of the food being processed.

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

            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. 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 240ºF.

            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.

            Test your equipment yearly, before the canning season begins for accuracy. I will be testing pressure canner dials at the Nashville Farmer’s Market this Friday at 9:00 a.m. for free. Just bring by your canner lid with dial gauge and the rubber seal. It will take just a few minutes and you can shop for fresh produce while I test your gauge.

            To kick off the canning season, I will also be conducting several food preservation classes this summer. The first one is scheduled for Tuesday, June 12 from 6:00 – 8:00 p.m. We will be learning how to freeze fresh fruits and vegetables correctly. On Thursday, June 14 from 6:00 – 9:00 p.m. we will learn the basics of pressure canning low-acid vegetables. The cost for these workshops is $10.00 each.

            If you can’t make the pressure canner testing at the Farmers Market, feel free to call me at 870-845-7517 to set up a time at our office. If you are interested in a complete list of Food Preservation Classes being offered this summer, call or visit the Howard County Extension Office located on the second floor of the courthouse in Nashville. And, of course, you can call our office at the telephone number above for all your canning questions. All of our information follows USDA guidelines for Home Food Preservation.

Recipe of the Week

            Try this recipe while berries are at their peak. It is super easy to make and is so delicious! This is a great project to do with children or if this is your first time making jam. Keep the jams safe to eat. Do not make any changes to ingredients or directions. Raspberries, strawberries, and blackberries work well in freezer jam recipes. This recipe is from the National Center for Home Food Preservation, (

Freezer Jams

Follow this basic recipe or use the instructions on the powdered pectin package.

2 cups crushed berries

4 cups sugar

1 package powdered pectin

1 cup water

Yield: 5 or 6 half-pint jars or freezer containers

  1. Sterilize canning jars and prepare two-piece canning lids according to manufacturer’s directions.
  2. Sort and wash fully ripe berries. Drain. Remove caps and stems. Crush berries.
  3. Place prepared berries in a large mixing bowl. Add sugar, mix well, and let stand for 20 minutes, stirring occasionally.
  4. Dissolve pectin in water and boil for 1 minute. Add pectin solution to berry-and-sugar mixture. Stir for 2 minutes.
  5. Pour jam into freezer containers or sterilized canning jars (as above indicated in step 1), leaving ½-inch headspace at the top.
  6. Close covers on containers and let stand at room temperature for 24 hours.
  7. Plastic freezer containers with tight-fitting lids work well for storing freezer jams and jellies.

Safe storage:

  1. Store unopened jams in freezer for up to 1 year.
  2. Store unopened jams in refrigerator for up to 3 weeks. Once container is opened, jams should be used within 2-3 days.
  3. Jams will mold or ferment if stored at room temperature.
  4. When jam comes out of the freezer, thaw overnight in the refrigerator. If the jam is too firm, you can soften it by stirring. If it tends to separate, stirring will blend it again.

By Jean Ince
County Extension Agent - Staff Chair
The Cooperative Extension Service
U of A System Division of Agriculture

Media Contact: Jean Ince
County Extension Agent - Staff Chair
U of A Division of Agriculture
Cooperative Extension Service
421 N. Main St, Nashville AR 71852
(870) 845-7517


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