Archive for Tuesday, July 20, 2010

Sullivan: Canners can’t always trust old methods

July 20, 2010

People still canning green beans at home using the boiling water canner instead of a tested pressure canning process are risking food loss and even worse, possible death or serious poisoning.

The K-State Research and Extension Office is receiving phone calls from people canning dozens and dozens of jars of green beans in boiling water and then losing all that work and food due to spoilage. Beans canned this way looked fine coming out of the canner, but are now turning cloudy and jars are popping open, even sometimes with force. These beans are definitely spoiling from being under-processed. But it could be worse: even if the jars still look good, it is possible that they contain botulism toxin from this unsafe canning practice.

Jars of improperly canned vegetables and meats can contain the deadly botulism toxin without showing signs of spoilage such as being seen in the reports mentioned. Those that do show signs of spoilage could also contain botulism toxin because they are showing other signs of under-processing.

Spores of Clostridium botulinum bacteria, as found naturally in soils, are very, very heat resistant. Even hours in the boiling water canner will not kill them if they are inside your jars of beans. Left alive after canning, they will eventually germinate into actively growing bacterial cells that will produce a deadly human toxin when consumed. The bacteria like the conditions inside closed jars of low-acid foods (such as vegetables and meats) sitting at room temperature, so they must be killed during the canning process for safe storage.

You can find the USDA-recommended procedures for canning green beans at home here:


The list of available vegetable canning processes is found at this menu:


And those for tomato and tomato products are here:


You can read a little more about botulism and ensuring safe home canned foods here:


And principles about safe canning at home are here:


Please be safe when canning foods for you and your family. Knowledge and recommendations change over time with scientific developments. You should use up-to-date recommendations and methods and not just rely on practices of past generations.

K State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well being of Kansans. Supported by county, state, federal and private funds, the program has county extension offices, experiment fields, area extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan. For more information, visit the Leavenworth County Extension Office at 613 Holiday Plaza, Lansing, 66043, call the office at (913) 364-5700, or visit our website at


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