Canning mistakes to avoid: Part 2

Preventing these mistakes can save you time, money and your life.

September 7, 2017 - Author: Michelle Jarvie, Michigan State University Extension

Summer may be dwindling, but canning season is still in full swing. Canning, and other forms of food preservation, aim to stave off the growth of spoilage organisms and dangerous bacteria so that fruits, vegetables, and meats can be enjoyed all year long. While not a terribly difficult process, canning is a science and there are some important steps required in order to make sure the food is safe. The following are common mistakes made during the processing portion of canning, and tips at preventing them: 

Not maintaining a sterile environment

Bacteria and spoilage organisms can enter your food at any time during the process of canning. It is important to make sure all jars and equipment are sterilized during use. Jars should be boiled for a minimum of 10 minutes (unless they are going to be processed for at least 10 minutes in boiling water bath), and all tools used for filling jars should be sterilized in boiling water as well. Your hands can also contaminate jars, so make sure to frequently wash hands, and avoid coughing or sneezing during the canning process. If you or someone in your home has been sick with a gastrointestinal illness, it is best not to handle food for 24-48 hours after your last symptom.

Re-using lids

The lid you took off last year’s raspberry jam might still look fine, but canning lids were designed to be used only one time. Never reuse lids.

Too little or too much headspace

Headspace is the space between your product and the underside of the lid. The amount of headspace needed is dependent on the product and the size of the jar, and vary from 1/4 “ to 1”. Not leaving enough headspace can cause boil over, in which product boils up under the lid and could prevent proper sealing, or promote mold growth. Leaving too much headspace can be problematic because there may be too much air to fully expel in the amount of processing time, leaving oxygen behind for bacteria and other organisms to grow in. Measure the headspace on every jar with an accurate tool.

Not adjusting for altitude

Do you know the elevation where you live? Many people don’t, but if you live at 1000 feet or higher, you need to adjust your processing time and/or pressure when canning. If you don’t know the elevation where you life, contact your local township office or MSU Extension office.

Failing to properly cool

When my mom and I can at home, my dad likes to make sure all the jars are facing the same direction and are evenly spaced in their cooling area, but handling jars during the 12-hour period immediately after processing is not recommended. Canning is the entire process from preparing the food, to putting it in jars and processing it, AND cooling properly. Jars should remain untouched for 12 hours to complete the process. After that, you can label them and move them to where they will be stored.

Avoiding these common mistakes will help ensure that your preserved food will be safe to eat all year long. For more information on canning, or to take a class, contact your local Michigan State University Extension office.

Tags: food preservation, msu extension

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