A K-State food scientist provides tips for canning at home, particularly for first-timers.
MANHATTAN, Kan. – Headlines the past few years have mentioned the comeback of canning, or preserving, foods at home. Preserving foods is a hobby for some, while many people view it as a way to cut down on grocery costs and control the ingredients that go into making homemade salsas, jams, jellies, pickles and many more fruits, vegetables and meats.
Karen Blakeslee, food science extension associate for K-State Research and Extension and coordinator of the Rapid Response Center, teaches food preservation courses and said she’s recently seen a surge of young adults, ages 20 to 40, with an interest in canning food at home.
Blakeslee said where these first-time food preservers are learning to can foods could be a problem, though, because not all the information available is correct, especially some information from the Internet. Improperly canning foods increases the risk of people getting foodborne illnesses.
“As extension professionals, we are offering hands-on canning classes in many locations across Kansas to teach people the importance of handling food safely,” she said.
In the courses, Blakeslee mentions these simple tasks are necessary before the canning process begins:
· Wash your hands before handling food.
· Start with a clean kitchen.
· Make sure food is washed well before you can it or freeze it.
· Make sure equipment, including the jars you plan to use, is washed and clean. Check jars for cracks and scratches to prevent breaking that could occur during the canning process or later on in storage.
· Use the right canning procedures and equipment based on what foods you plan to preserve.
Determine your method
“For high-acid foods, such as fruits, jams, jellies and pickles, we can use the boiling water-bath method,” Blakeslee said. “With a boiling water bath, you use a large stockpot, rack and lid. It’s simple, and you don’t necessarily have to buy a specific water-bath canner.”
Make sure the stockpot is tall enough to hold the filled jars and the water, she said. The water needs to cover the tops of the jars by at least 1 to 2 inches.
“Foods such as vegetables that are not pickled and meats are low-acid foods and must be pressure-canned,” Blakeslee said. “There is no other option.”
Several manufacturers make pressure canners, and she said there are two main kinds available: weighted gauge and dial gauge. The dial gauge pressure canners must be tested every year to make sure the gauge is accurate. If it’s off by more than 1 pound, up or down, consider getting replacement parts or a new pressure canner. Most local extension offices in Kansas have a pressure gauge tester available and can test it at no cost.
“One thing we caution you not use is a pressure cooker, which basically looks like a sauce pan,” Blakeslee said. “They are not designed for canning. They’re not big enough or strong enough.”
She said a pressure canner, however, could have multiple uses. People can use it as a pressure cooker to cook a large pot of baked beans, for example. When not using the pressure part of the pressure canner, people can use it as a water-bath canner or stockpot.
Focus on temperature
Blakeslee recommends cleaning and preheating the canning jars before placing food in them. Submerge the jars in boiling water for 10 minutes to sterilize.
“An alternative is to wash the empty jars in your dishwasher and leave them in the closed dishwasher until ready to use,” she said. “If the food you are canning processes for more than 10 minutes, pre-sterilizing the empty jars is not necessary as the jars get sterilized during the processing.”
The water bath should reach boiling temperature, 212 degrees Fahrenheit, and the pressure canning method requires at least 240 degrees F to prevent botulism, a rare but serious paralytic illness that could be foodborne. It is caused by a nerve toxin produced by bacteria, according to the Centers for Disease Control and Prevention.
Another important thing to remember is to adjust processing times for altitude, Blakeslee said. People might not realize that most food preservation recipes, whether they’re from extension, the U.S. Department of Agriculture, or even the Ball Blue Book, list process times for altitudes of 0 to 1,000 feet. Always refer to the general instructions for more information.
“Eastern Kansas is below 1,000 feet, but most of central and western Kansas is above 1,000 feet,” she said. “If you’re using a boiling water bath, you have to add extra time to get up to 212 degrees F. If you’re pressure canning, you will need to add pressure to get the temperature up to 240 degrees F.”
Canned food storage
Blakeslee said to make sure the jars are sealed before storing them. The lid on a sealed jar will concave following a “ping” sound. After processing, let the jars cool completely before checking lids and rings to allow the jars to seal on their own. People should lightly press on the lid to make sure it is tight and not bouncing up and down. They can choose to leave the rings around the lids on or take them off.
“If you leave the rings on for storage, I recommend that you clean the jars well,” she said. “Remove the ring, clean it and the jar to remove any residue, and let dry. This will help prevent the ring from rusting and will be easy to remove later.”
Blakeslee recommends people consume home-canned food within one year. If the environment changes frequently where the canned goods are stored, that could influence the safety and quality of the preserved food.
“The best storage conditions are cool, dry and dark,” she said. “If you have it out in the garage, by your furnace or above your dryer -- anyplace where large temperature changes can occur -- that can change the safety of the product. Dark storage conditions will prevent light from causing color changes of the food in the jars.”
Blakeslee recommends that first-time canners or anyone needing a refresher course attend one of the hands-on classes offered by K-State Research and Extension. To find out more, contact your local extension office.
More information about canning and food safety is available online on the Rapid Response Center’s website or K-State Research and Extension’s food safety website.