Home canning is a great way to store a summer's garden bounty -- but improper processing can lead to some serious health issues. So can keeping canned items for more than a year. Any jar of beans or other food this cloudy, discolored and lacking a label indicating the date it was canned should be tossed out immediately.

This story was originally published in 2019.

Home canning is a great way to preserve the season’s freshest produce to enjoy all year. Though it may seem daunting, with a little knowledge and the right supplies, you can learn to become a successful canner.

But experts caution it’s important to understand that canning is a science, so recipes from reputable sources need to be followed exactly.

“Canning is not one of those things that you can just wing it and you will be OK. A lot could go wrong,” said Lisa Fishman, a regional supervisor and nutrition education professional with the University of Maine Cooperative Extension.

Still, Fishman wants to see more people embrace the practice. “I want to see a lot of people canning their own [food] and saving money … but I want people to do it the right way,” Fishman said.

Author Marisa McClellan, who teaches water bath canning and has written several cookbooks about canning, including the recently released “Food in Jars Kitchen,” agrees. “Yeah, [canning is] cooking, but it’s also science.”

Water bath canning is a great entry point for people who are interested in trying canning.

What you need to know to try water bath canning

What you need:

  • A large pot — Although you can purchase pots made specifically for canning, you don’t need a specialty one. “Being the thrifty Mainers we are, you can use any pot that is deep enough to cover the cans by two inches that you can fit a rack in the bottom of it,” Fishman said.
  • A rack for the jars — This sits inside your pot. Likewise, you don’t need special gear. Just something large enough to fit so the jars don’t sit on the bottom of the pot.
  • Something to lift the jars — Jar lifter tools are available, but anything that will grip and lift jars will do.
  • Jars with the two piece lids — Be sure that you purchase or use jars intended for canning. “There are a lot of beautiful jars out there. The spaghetti jars are made to look like canning jars. Those jars are not tempered to be used for multiple cannings,” Fishman said. So stick to real canning jars.
  • A ladle for filling the jars — Again, you don’t need something special for this. “You can use any kind of implement you can find in your kitchen to ladle food into a jar and you can jerry rig things to lift jars,” Fishman said.

What to do:

  • Consider taking a class to learn the basics. The UMaine Cooperative Extension offers ones throughout the state. Check out extension.umaine.edu to find ones near you.
  • Find reputable sources for recipes for canning. The “Ball Complete Book of Home Preserving,” for instance, is filled with recipes and information for successful canning. Other good books include “Pressuring Summer’s Bounty,” “Preserving Memories and Food in Jars.”
  • Make sure that you only can high-acid foods using the water bath method. “Most fruit is going to be high in acid on its own,” McClelland said. Blueberries, strawberries, peaches and pears, for instance, are appropriate for water bath canning. However, tomatoes are trickier. “We think of tomatoes as being very acidic but plums are actually way more acidic,” McClelland said. Both Fishman and McClelland said that tomatoes today have been bred to be less acid than those grown 50 years ago — which means that things your grandmother canned with the water bath method may no longer be safe to do so. “We don’t necessarily know how acidic a tomato is anymore,” Fishman said. “The USDA actually recommends that you bolster your acidity of home canned tomatoes with bottled lemon juice.” Bottled is important because it has a standardized acidity level — something that can’t be guaranteed with fresh produce.
  • Don’t use outdated information. Books from prior to the late 1980s are based on outdated canning information. They shouldn’t be used.
  • Check with your local cooperative extension if you aren’t sure a recipe is appropriate for water bath canning or if you have questions. They are the experts and there to help.

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