Berny Unruh: Canning is serious business

Staff Writer
Hays Daily News
Berny Unruh

My grandmother had a huge garden and she spent many days in the summer and fall canning produce for us to use during the winter months. I remember hearing the “ping” as the jars sealed.

One of the most important things to remember that canning is serious business and the rules must be followed to prevent a foodborne illness. There are two main points to remember when canning foods at home:

• Use a current (not older than 8-10 years) recipe from a credible tested source such as Extension Office, USDA, National Center for Home Food Preservation or a Ball canning book.

• Follow the directions EXACTLY.

I often hear that a family has been using a certain recipe for many years and nothing bad has happened. But canning is a science that’s continually being researched and over time things do change. The best way to stay updated on the rules is to only use current recipes from credible sources.

In addition to following an approved recipe, it’s important to use the proper equipment and methods. Currently, there are only two approved methods for canning food: using either a water-boiling canner or a pressure canner.

Other canners and methods used in the past, like open-kettle and steam canning are no longer recommended. Open-kettle canning and the processing of freshly filled jars in conventional ovens, microwave ovens, and dishwashers are not recommended, because these practices do not prevent all risks of spoilage.

The latest questions coming into the Extension Office have been about the electric pressure cookers. Many of the instruction books that come with these small appliances give instructions for canning. The problem is these cooking appliances cycle to keep the heat and pressure up so the heat and pressure are not consistent for the entire pressure-cooking time. Do NOT use the electric pressure cookers for canning.

It is also important to use proper canning containers. Regular and wide-mouth Mason-type, threaded, home-canning jars with 2-piece self-sealing lids are the best choice. They are available in ½ pint, pint, 1½ pint, quart, and ½ gallon sizes. The standard jar mouth opening is about 2-3/8 inches. Wide-mouth jars have openings of about 3 inches, making them more easily filled and emptied. Half-gallon jars may be used for canning very acid juices. Regular-mouth decorator jelly jars are available in 8 and 12 ounce sizes. With careful use and handling, Mason jars may be reused many times, requiring only new lids each time. When jars and lids are used properly, jar seals and vacuums are excellent and jar breakage is rare.

We have had phone calls about the shortage of canning supplies available for purchase. Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids but only for canning acid foods. However, you should expect more seal failures and jar breakage. These jars have a narrower sealing surface and are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. A tiny scratch or crack in glass may cause cracking and breakage while processing jars in a canner. Mayonnaise-type jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for use in canning any food at home.

Jars with wire bails and glass caps make attractive antiques or storage containers for dry food ingredients but are not recommended for use in canning. One-piece zinc porcelain-lined caps are also no longer recommended. Both glass and zinc caps use flat rubber rings for sealing jars, but too often fail to seal properly.

As you can see, canning is a very involved process. There are a lot of do’s and many do not’s, and it’s hard to keep track of them all. The best advice is to make sure you have credible recipes that have been tested by a credible company, follow them exactly, and if you do have questions call the Extension Office.

Berny Unruh is the Family and Community Wellness Agent for the Cottonwood Extension District. She can be reached at 785-628-9430 or at