Canning safety: Separating facts and fiction
Late summer is canning season. And if your garden has been thriving, you’re probably thinking about canning some of your favorite vegetables to enjoy later this year and in the cold winter months. But to keep your food safe, you’ll need to know some facts from fiction.
In a recent article Gina Taylor, a WVU Extension Service Family and Community Development Agent, debunked a few myths and provided expert advice on safely preserving your food.
The first myth is about open kettle canning. Open kettle canning is a process where food is heated or cooked in an open pot, and then put into a jar with a lid placed on. The lid seals from the jar or bottle cooling.
Taylor explained that open kettle canning is a dangerous practice. “Foods prepared in this manner present a serious health risk – particularly with regard to low-acid foods such as vegetables, meat, seafood and poultry. All foods should be canned using a boiling water bath canner or a pressure canner, depending on the level of acid in the foods, Taylor said. “Low-acid foods that are not canned properly, can present a risk for botulism.”
Botulism is a rare but potentially deadly illness caused by a poison most commonly produced by a germ called Clostridium botulinum. The germ is found in soil and elsewhere and can survive, grow and produce a toxin in certain conditions, such as when food is improperly canned or held at too low of temperatures. The toxin can affect your nerves, paralyze you, and even cause death.
You cannot see, smell or taste botulinum toxin — but taking even a small taste of food containing this toxin can be deadly.
“That is why it is very important to get your canner up to the proper temperature — 240 degrees F — to destroy the bacteria,” Taylor said. “This high temperature is only possible in a pressure canner because regular boiling water only reaches 212degrees F.”
The next myth Taylor addressed was that food in unsealed jars is still safe to eat.
“Canning takes some time and effort, and one of the most frustrating parts of canning is when a few jars don’t seal. What should you do when a few jars don’t seal? Throw the contents away? Not necessarily. Unsealed jars can be re-canned if they are discovered within 24 hours.”
“To re-can unsealed jars, simply remove the lid and check the jar sealing surface for tiny nicks. Change the jar, if necessary. With two-piece metal lids, use a new prepared flat lid. Reprocess the jars using the same processing time described in your recipe.”
If there is any doubt if safe canning guidelines have been followed, do not eat the food. Home-canned and store-bought food might be contaminated with toxins or other harmful germs if:
- the container is leaking, bulging or swollen
- the container looks damaged, cracked or abnormal
- the container spurts liquid or foam when opened
- the food is discolored, moldy or smells bad
If the container or the food inside has any signs of contamination, throw it out. If any of the food spills, wipe up the spill using a solution of 1/4 cup bleach for every two cups of water.
Never taste food to determine if it is safe. Do not taste or eat food that is discolored, moldy or smells bad. Do not taste or eat food from cans that are leaking, have bulges or are swollen or look damaged, cracked or abnormal. Do not taste or eat food from a can that spurted liquid or foam when it was opened.
“Lids should not be used a second time since the sealing compound becomes indented by the first use, preventing another airtight seal. Screw bands may be reused unless they are badly rusted, or the top edge is pried up, which would prevent a proper seal.”
The last myth Taylor addressed was about green beans — “Are the green beans that are put in a boiling water bath canner safe to eat because I boil the jars longer than recommended?”
“Green beans are a low-acid food and must be canned in a pressure canner to eliminate the growth of the bacteria clostridium botulinum.”
Taylor explained that simply extending the canning time in a boiling water bath canner is not enough to destroy deadly bacteria. “Green beans must be canned at a temperature of 240 degrees F, which can only be achieved using a pressure canner.”
University Extension Programs
For more information and to learn how to safely can your food, there are several University Extension Programs with information and canning courses.
Utah State University’s Preserve the Harvest extension offers an online lecture series on preserving your garden harvest, as well as an online canning course.
Other resources on the page include information and instruction on:
- Selection, preparation and pretreating of foods
- Food storage and packaging
Iowa State University is another institution offering free instructional courses on food preservation.
ISU’s Food Preservation 101 is a one-hour online course. During which, nutrition and wellness specialists will:
- Discuss various food preservation techniques – pressure canning, hot water bath canning, dehydration and freezing.
- Provide science-based, reliable food preservation resources.
- Answer general food preservation questions.
Food Preservation 101 will be hosted numerous dates and times between May and Sept. For more information and to register, visit their website.
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