Pressure or Boiling Water Bath Canning

Now that many novices have planted gardens and will be preserving the fruits and vegetables for the first time, it is more important then ever to discuss how to safely preserve these foods at home.

A common question we receive at Cooperative Extension is: How long do I process my green beans in a boiling water bath? The answer is: Green beans and any other low acid food cannot safely be canned use the boiling water bath method of canning.

There are only two safe ways of canning, depending on the type of food being canned. The boiling water bath method is safe for high acids foods like fruits, tomatoes, pickles and jellies. Pressure canning is the only safe method of canning vegetables and meats, because they are low acid foods.

Clostridium botulinum bacteria are the main reason low-acid foods must be pressure canned to be safe. Clostridium botulinum is a common soil microorganism that produces a very lethal poison called botulism. Botulinum spores can survive boiling water temperatures (212 degrees F.) and live in the absence of air – (such as, in a sealed canning jar). When this occurs, deadly botulinum toxin can be produced.

The spores of Clostridium botulinum can be destroyed by canning the food at a temperature of 240 degrees F. or above for a specific period of time. This temperature can only be achieved by processing the foods under pressure in a pressure canner.

Acidic foods – most fruits, acidified tomatoes, jellies and jams, and properly pickled vegetables – contain enough acid that the Clostridium botulinum spores cannot grow and produce the deadly poison. So, these foods can be safely canned in a boiling water bath canner. Because tomatoes and figs have less acid than other fruits, acid in the form of lemon juice or citric acid must be added to insure they are acidic enough for boiling water bath canning.

We caution folks, to be sure to use the most up-to-date methods and recommended processing times when canning any foods at home. Why go to all the trouble and expense of preserving foods at home and not follow the proper procedures to make sure the food is safe and wholesome.

You can receive free information and directions on canning fruits and vegetables as well as all other food preservation methods at your County Extension Center. Call or come by today.