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Foodborne botulism is a rare, but life-threatening condition resulting most commonly from improperly home-canned foods.
Clostridium botulinum bacteria produce toxins that can be present in foods. Clostridium botulinum toxins create heat-stable spores in oxygen-free environments. In order to starve spoilage microorganisms (yeasts, molds, etc.) from the ability to grow, oxygen is driven out of canning jars during processing, creating a desired “popping” sound of lids sealing to jars. When ingested, clostridium botulinum neurotoxins attack the body’s central nervous system resulting in drooping of the face and eyelids, difficulty swallowing, and in severe cases, victims face the inability to breathe due to paralysis of the diaphragm.
So how do you preserve food? Follow a tested recipe! Tested recipe resources include the book “So Easy to Preserve,” the 100th edition of the “Ball Blue Book,” and the National Center for Home Food Preservation’s website. Tested recipes have been researched to ensure safety by examining the pH, water availability and processing times.
Clostridium botulinum grows at a pH at or above 4.6 (pH is a measurement of how acidic or alkaline something is with low numbers being more acidic). For that reason, high-acid foods can be canned using a boiling water bath canner to reach a temperature of 212 degrees. High-acid foods include fruit products, acidified or pickled foods and fruits with the exception of figs.
Low-acid foods, however, must be pressure-canned. When foods lack the proper acidity to prohibit clostridium botulinum from growing, they must be pressure-canned in order to reach a temperature of 240 degrees. Low-acid foods include meats, poultry, seafood and vegetables, excluding rhubarb and tomatoes.
Yes, this means you should not be using the boiling water bath method for tomatoes, green beans and potatoes!
When following a tested recipe, be sure not to alter the recipe in any way, including the processing time. Processing times are studied to determine how long it takes for the oxygen to be driven from the jars to create a seal. Altering the sugar or salt content of a recipe can allow pathogens to grow. When water is not bound by salt or sugar, it is available for microorganisms to use and grow.
Drying, freezing and fermenting foods from your garden are safe alternative ways to preserve. Dehydrating preserves food by stopping the growth of microorganisms by removing the water.
When freezing, it is necessary to blanch vegetables before placing in the freezer. By blanching, the enzymes responsible for loss of flavor, color and texture are stopped. Blanching also removes dirt and microorganisms while softening the vegetables for easier packing.
Fermenting foods is the final method of food preservation. Fermentation is all about managing pH levels by allowing the pH to rise to the point that good bacteria thrives to achieve flavor, but low enough that harmful bacteria is killed off. Fermentation takes quite a bit of time, but the finished product is something to be proud of.
Once foods have been fermented, you can store them in the refrigerator, freezer or even home-can the product by following an approved recipe. Dried and fermented foods vary in their shelf-life. Frozen and home-canned foods are of good quality for up to one year. After a year, the foods are safe to eat, but the quality diminishes.
If you are planning to break out the pressure canner this year and have a dial gauge lid, you’ll want to have the dial tested for accuracy. The N.C. Cooperative Extension in Wilson County can test your dial gauge if it was manufactured by Presto. If your dial gauge needs testing but is not a Presto canner, you can send your dial gauge back to the manufacturer for testing. For questions or approved canning recipes, contact the N.C. Cooperative Extension, Wilson County Center, at 252-237-0111.