Home canning is rife with horror stories, from exploding jars and moldy jams to — heaven forbid — the woes of botulism. As an amateur homesteader, I have made a number of false starts at home canning. When my bumper crop came in from my garden last summer, I even purchased a set of canning jars and bought a home canning guide. Now I use the jars as cups and the booklet is gathering dust on my bookshelf, squeezed between cookbooks and back issues of Bon Appetit magazine. I was too intimidated by the potential pitfalls to take the plunge.
Canning is a method of preserving food by storing it in containers that are sterilized and sealed by heat. It is a relatively new method of food preservation when compared to techniques like smoking meat and making sausage. It all started at the end of the 18th century, when Napoleon Bonaparte offered a reward to whoever could develop a safe food preservation method for his army. Nicholas Appert took on the challenge. He debuted his method in 1809, which involved heat-processing food in glass jars reinforced with wire and sealing them with wax.
Since then, canning has evolved to improve its safety and effectiveness. There are three main methods for canning: pressure canning, steam canning and water bath canning. Each has its advantages — steam canning is faster and more water-efficient than both pressure and water bath canning, for example — but sometimes, using the wrong type of canning for a recipe can get you sick.
Even through the tried-and-true techniques, rookie mistakes can lead to canning catastrophes. Hot jars can explode if they are put on cold countertops. If the rims of the jars aren’t wiped before sealing, then nasty bacteria can get into food. Using old home canning recipes can also lead to disaster. Not only have fruits like tomatoes changed in acidity over time, but even slight inaccuracies in homemade recipes can make you sick. Sorry, Grandma.
Despite the risks, I have gotten to a point where I feel like my fear of canning is holding me back. Canning is an essential homesteading skill, and a great way to preserve a bountiful harvest to eat all throughout the winter. Plus, there are so many fun recipes to try with canning. If I had known how to can last summer, I could have made a yummy cherry tomato jam instead of eating my whole harvest one by one before they went bad (though that wasn’t the worst alternative). I decided to face my fears of foodborne illnesses and Mason jar shrapnel.
Learning to try
I recruited Kate McCarty, food systems professional at the University of Maine Cooperative Extension. She teaches a variety of canning and food preservation classes through the University of Maine Cooperative Extension, so I figured she’d be well equipped to handle my canning anxieties.
I challenged Kate to find a recipe using seasonal produce that we could make — in February. She chose a recipe for balsamic onion jam from “The All New Ball Book of Canning and Preserving,” with a splash of maple syrup (we are in Maine, after all).
Kate explained that, especially for beginners, choosing a trusted source for canning recipes is essential. She said that new canners will often make the mistake of using an online recipe and, without the experience that comes with years of canning, will not be able to recognize when measurements or timing are off. She recommended sticking to recipes from university cooperative extensions, Ball or the U.S. Department of Agriculture (USDA), which have been tested in a lab for safety (and, presumably, deliciousness).
Kate brought a bunch of materials to the Penobscot County extension office in Bangor, including a water bath canner (basically, a giant stock pot with a rack in the bottom), 4-ounce glass Ball jars with new screw bands and lids (Kate said you can use the rings nearly infinitely, but lids should only be used once because the sealing agent wears away; luckily, they can be purchased in separate packs), coated hand-held grip clamps to remove the jars, the cookbook and all the ingredients for our recipe.
Kate’s equipment was fairly fancy, but she said you could get started for cheap by purchasing a less expensive water bath canner or digging around the thrift store. She warned against purchasing used jars, though, as they could be damaged or overpriced (new jars are fairly inexpensive, anyway, so anything over $1 a piece is too expensive).
A trying experience
Kate and I filled the pot with water to boil and washed the jars, lids and screw bands. We lowered the jars into the boiling water to heat up (not sterilize — Kate said that is only necessary for recipes with short canning times — but to prevent breakage when we added hot jam to the jars). Then, it was time to make the onion jam.
First, we prepared the ingredients. We chopped the onions and mixed the balsamic vinegar and maple syrup along with a few spices: bay leaf, salt and white pepper. We sauteed all the ingredients together in a separate pot until the onions were translucent and everything emitted a pungent but delicious odor.
Then, we added the pectin, a powdery substance extracted from fruit sources for home canning recipes. Kate explained that pectin — a polysaccharide that gives fruit its firmness — helps jam set. Otherwise, we would have to boil the jam to a set point (which could take almost half an hour and requires a canning thermometer) and add significantly more sugar to help everything gel together. With the pectin, we could get away with a cup of sugar and a few cups of apple juice.
We had to let the jam boil to a point where it could not be stopped by stirring. Kate said that a phrase often used in canning is a “full rolling boil, one that cannot be stirred down.” All this means is that the mixture doesn’t stop bubbling when you stir it. If I had read this in a recipe without explanation, I would have immediately started doubting the quality of my boil and probably would have scrapped the whole thing entirely. I appreciated Kate demystifying the lingo.
Once the jam was ready, we funnelled it into the hot jars. Because it looked a little syrupy still, Kate took a tiny bit of the onion jam and put it on a plate in the freezer to see if it would congeal. After only a few minutes, our onion jam had a reassuringly gelatinous consistency.
Kate handed me a special tool to measure the proper amount of “headroom,” space in the jar that accounts for the expansion of the material inside so that jam can expand as its cans without breaking the seal on the jar. Then, we wiped the rims of the jars to ensure the lids would seal.
Then, we put the rings on until they were “fingertip tight.” It’s another one of those phrases often used in canning recipes that would have stopped me dead in my botulism-fearing tracks if I were attempting it alone, even though all it means is to tighten the bands with only your fingertips and not your whole hand. Screwing the lids on too loose might let the jam escape, but screwing them too tight could also compromise the sealing process.
We put the filled jars back in the boiling water to seal. After the 15 minutes of boiling and five minutes of rest demanded by the recipe, I lifted the jars gingerly out of the water bath. We put them on a baking rack so they wouldn’t crack when they touched the cold countertop. We listened for the seals to pop. Most of them did, and it was extremely satisfying.
All that was left was for Kate and I to spread some onion jam on a cracker and take a bite. It was delicious: sweet, savory and even a little spicy thanks to the white pepper. I was already thinking of ways to use balsamic onion jam (on a charcuterie board with goat cheese and salty meats, perhaps, or smeared on a juicy burger or pulled pork sandwich).
My tried-and-true takeaways
With a little bit of guidance, home canning is much less intimidating than attempting it with written instructions alone. After my afternoon with Kate, I feel like I have the knowledge and confidence to go out and start canning on my own. Taking a canning class, especially one with your local cooperative extension, is a great way to get started with home canning.
If you are getting started on your own, I have some recommendations for your shopping list: a water bath canner, new jars with lids and screw bands, a pair of canning jar lifters, a tool to measure headspace, liquid and powdered pectin (the type you use will depend on the recipe) and — of course — “The All New Ball Book of Canning and Preserving.” Yes, this might cost a bit at the outset, but I think you will get so much joy out of what you can create.
When it comes to what exactly you preserve through the process, don’t be afraid to be experimental. With the right guide (and choosing the right guide is essential, especially in the early days of your canning journey), the possibilities seem endless. Onion jam, for example, may sound weird at first, but it is scrumptious and versatile. I can’t wait to experiment more, especially once my yearly harvest comes in.
By the way, if you want to try to make onion jam that Kate and I concocted, you can follow along with the recipe below.
Makes about 10 4-ounce jars
Adapted from “The All New Ball Book of Canning and Preserving”
2 pounds onions, diced
½ cup balsamic vinegar
½ cup maple syrup
1 ½ teaspoons salt
2 teaspoons ground white pepper
1 bay leaf
2 cups apple juice
3 tablespoons Ball low or no-sugar pectin
½ cup sugar
1. Prepare jars by washing with warm, soapy water and rinsing well. Fill boiling water bath canner halfway with water and bring to a boil. Place jars in canner and keep warm. Wash lids and screw bands and set aside.
2. Combine onions, vinegar, maple syrup, salt, pepper and bay leaf in a large stock pot. Heat over medium heat for 15 minutes, until onions become translucent, stirring occasionally.
3. Add apple juice and pectin powder and stir to dissolve. Increase heat and bring onion mixture to a full rolling boil, or one that cannot be stirred down. Stir constantly.
4. Add sugar and stir to dissolve. Bring mixture back to a boil and boil for one minute, stirring constantly.
5. Remove bay leaf and ladle hot jam into hot jars, leaving ¼ inch headspace. Wipe rims, apply lids and screw bands until fingertip tight.
6. Process in a boiling water bath for 15 minutes. When processing time ends, turn off heat, remove canner lid and let jars sit for 5 minutes. Remove jars, let cool 24 hours undisturbed. Check for seals, then label, date and store in a cool, dark, dry place.