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Preserving the Summer Bounty

Sharon McDonald, MEd, RD, LDN, Extension Educator | Penn State Extension | July 17, 2019

As we approach the heart of home food preservation season remember to always preserve food using tested and research-based guidelines. This is especially critical if you can foods as a preservation method. The greatest food safety concern with improperly home canned foods is Botulism. Just recently, an individual canned frozen peas in a water bath canner following a recipe for canning peaches! Two individuals developed botulism. Fortunately, they did not die as they quickly sought medical help and were treated.

Foods can be classified into two categories – high acid and low acid. High acid foods include most fruits, jam, jelly, pickles and pickled foods. Because of their higher acid level (pH below 4.6) they can be canned in a water bath or atmospheric steam canner following tested recipes. Processing by these methods will destroy spoilage microorganisms and other bacteria that may be present. Low acid foods (pH of 4.6 or above) include vegetables, meats and combinations of these foods. Low acid foods must be canned in a pressure canner to destroy Clostridium botulinum spores. These spores are not destroyed at boiling water temperatures. They are destroyed at temperatures around 240°F which can only be reached under pressure. When it comes to tomatoes, their acid level is on the borderline, right around pH 4.6, therefore when canning tomatoes in a boiling water bath be sure to add additional acid in the form of lemon juice or citric acid.

Following tested and research-based recipes/guidelines is also important. Penn State Extension, National Center for Home Food Preservation, USDA and other cooperative Extension services are the best sources for recipes/guidelines when it comes to home canning. Recipes from these sources have process directions that will assure the destruction of microorganisms that may be present in filled jars. While a google search will bring up hundreds of recipes and recommendations, when it comes to home canning be sure to look at the reference and error on the side of safety by using a reputable reference as listed above.

One method of canning that is no longer recommended is open kettle or hot fill. While putting hot food in a mason type jar with a lid will create a vacuum seal, it is not an airtight seal. Without further processing, microorganisms that cause spoilage and illness are not destroyed.

For more information visit the Penn State Extension home food safety page, Let’s Preserve or plan on attending our workshop Home Food Preservation: Introduction to Preserving on August 22nd from 6-8 PM at St. Paul Lutheran Church in Pine Grove Mills.

Register at or call 1-877-345-0691. For additional information contact Sharon McDonald, or 814-865-6953.

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