Canning extra vegetables and fruits from your garden is a great way to save money and enjoy them year-round, but you must take care when processing foods at home.
“Getting recipes off of Pinterest or other Internet sites can be risky, because you cannot be sure the food will be safe once processed,” cautioned Wenquing Xu, consumer food specialist for food safety with the LSU AgCenter.
For example, you might want to alter a recipe by cutting the sugar content. But the sugar not only sweetens the fruit, it acts as a binder to absorb excess water that can harbor bacteria, said Xu.
By cutting the amount of sugar, you may inadvertently provide an opportunity for deadly microorganisms to form in the jar, said Xu.
Though safe, low-sugar recipes are available from trusted sources, modifying your own recipe could prove disastrous, she said.
In the United States, an average of 21 cases of food-borne botulism are reported each year, according to data from the AgCenter.
Most of the cases are associated with home-processed and home-canned foods, especially low-acid foods such as vegetables, seafood, meats and poultry.
Old family recipes may be suspect as well, Xu said. The U.S. Department of Agriculture has made significant changes in recommendations for home canning since 1994.
“It’s best to use recipes from trusted sources, such as the LSU Cooperative Extension, the USDA or the National Center for Home Food Preservation,” Xu said.
Canning deactivates enzymes in the food, that cause flavor loss and changes texture over time.
Xu says the food’s acid content, or pH, determines how it should be processed.
There are two types of canning: boiling water canning for acidic foods, which includes most fruits and pickles, and pressure canning for low-acid foods, such as vegetables.
Some foods, such as tomatoes, figs and Asian pears, require additional acid to be safely processed in a boiling water canner, according to LSU AgCenter information.
Adding powdered citric acid that is made for the canning, or commercially bottled lemon juice, will help prevent microbial growth. Add 1 tablespoon of lemon juice or ¼ teaspoon of powdered citric acid per pint directly into the jars before you add the tomatoes, figs or pears. For quart jars, use 2 tablespoons of lemon juice or ½ teaspoon of powdered citric acid.
The USDA does not recommend canning summer squash or zucchini. Instead, preserve these vegetables by pickling or freezing.
Here are a few other canning tips:
Always use jars made especially for canning because they can withstand the extreme temperature changes involved. Make sure there are no chips or nicks on the jars.
Sterilize jars, lids and screw bands according to manufacturer’s directions.
Screw bands can be used repeatedly as long as they are not dented or rusted.
Always use new flat metal lids for a proper seal. The underside of the lids contains a sealing compound, which creates a tight seal.
“When offering safety information on home canning to people, it’s sometimes hard for them to understand why they may need to do something differently from what they have done in the past,” Xu said. “So I tell them it’s like buckling your seat belt. Long ago, most people didn’t see the need.”