Health Law

Proper canning steps ensure food safety, prevent botulism

By Marler Clark

I moved to Seattle in 2002 and have never experienced a heat wave in late May and early June like the one we are enjoying now. There are few places I'd rather be than Seattle in the summertime, and to our benefit this year, everyone in the Seattle area who planted their garden around Mother's Day is enjoying watching their tomatoes bloom, mint grow full, and and snow peas sprout.

Where I grew up, every one of my neighbors had a huge, amazing garden full of strawberries, corn, potatoes, pumpkins, and a variety of other vegetables. We kids complained every summer while we weeded rows and picked potato bugs off leaves, but we loved the fresh produce on our dinner tables. Unfortunately, most of our moms decided to stop gardening when we kids got old enough to hold jobs and the free weeding disappeared. One of my neighbors, however, continues in the tradition of her Midwest roots and grows massive amounts of tomatoes, pickles, and other veggies that are great for canning and can be enjoyed year-round.

Because my neighbor has canned for as long as she can remember, she is fully aware of the food safety risks improperly canned foods can pose to an unassuming person. I never worry about suffering botulism poisoning when I eat her canned salsa, but people who are new to canning should read up before jumping in to what can be an extremely dangerous endeavor.

Connie Aclin, extension educator with the LSU AgCenter, wrote a recent article about the necessity for following proper canning procedures to prevent foodborne illness, particularly botulism, that appeared in the Shreveport Times:

For example, pressure canning is the only recommended method for canning meat, poultry, seafood and vegetables. The bacterium Clostridium botulinum is destroyed in low-acid foods when they are processed at the correct time and pressure in pressure canners. Other methods, like boiling water bath or "open-kettle" methods for these foods poses a real risk for botulism poisoning.

Whether food should be processed in a pressure canner or boiling-water canner to control botulinum bacteria depends on the acidity in the food. Acidity may be natural, as in most fruits, or added, as in pickled foods. Low-acid canned foods contain insufficient acidity to prevent the growth of these bacteria.

Botulism is a serious, sometimes deadly, illness caused by the bacterium Clostridium botulinum. When ingested, the bacterium produces a toxin, which causes paralysis. Classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated, and have a weak cry and poor muscle tone. These are all symptoms of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to cause paralysis of the arms, legs, trunk, and respiratory muscles. In foodborne botulism, symptoms generally begin 18 to 36 hours after consuming contaminated food, but they can occur as early as 6 hours or as late as 10 days after consumption.

Botulinum toxin causes flaccid paralysis by blocking motor nerve terminals at the myoneural junction. The flaccid paralysis progresses symmetrically downward, usually starting with the eyes and face, then moving to the throat, chest, and extremities. When the diaphragm and chest muscles become fully involved, respiration is inhibited and unless the patient receives treatment in time, death from asphyxia results.

If you're planning to can this summer of fall, call your local university extension office about proper canning procedures to prevent botulism. The Oregon State University Extension offers online information and a hotline you can call with canning questions.

Full post as published by Food Poison Blog on June 04, 2009 (boomark / email).