Many people fear home canning. And it’s true. There are home canning mistakes that can kill you, or at least make you very sick.

This doesn’t mean that you should be afraid to home can. Home canning is very safe, as long as you follow safe canning practices.

In this article I cover some home canning mistakes that can kill you, and how to avoid them.

Home Canning Mistakes that Can Kill You

The top potentially lethal mistakes home canners make include using the wrong type of device for canning, not adapting canning recipes for altitude, making up their own canning recipes without using principles set forth by the USDA, using unapproved thickeners and hurrying up the cooling process.

Keep reading, to dive into all the details of how to can safely at home.

Making Up Your Own Canning Recipes

Pro Tip: One of the best ways to avoid making mistakes with canning recipes is to follow a trusted guide such as The Ball Complete Book of Home Preserving (on Amazon).

Let’s say that you have a favorite chicken pot pie filling recipe that you would love to add to your prepper pantry. Should you make up a big batch, and can it? Maybe. But unless you understand safe canning principles, you may inadvertently can something that isn’t safe.

There are a couple of ways to avoid illness or even death when it comes to canning recipes.

The first option is to only follow tested canning recipes found on sites such as the National Center for Home Food Preservation. If you follow recipes on those types of sites, you’ll know beyond a doubt that they are safe recipes, because they have been thoroughly tested.

But let’s get back to the chicken pot pie filling example. How can you safely can that at home? As you’ll see a bit further in this article, using thickeners is one of the canning mistakes that can kill you. And since chicken pot pie filling is thick, it’s unsafe to can.

Having said that, you can safely can your chicken pot pie filling minus the thickener, and then add the thickener when you want to use it. When it comes right down to it, this is the same thing as canning chicken soup.

First, can an approved chicken soup recipe. Then when you’re ready to make your chicken pot pie, heat up the “soup” and add thickener such as corn starch or a roux made with flour to thicken the soup.

While this process isn’t as easy as opening a can of already thickened chicken pie filling, it gets you half-way there. By the time you’ve heated the oven and gotten the pie crust ready, your home-canned chicken pie filling can be thickened and ready to go.

As you gain experience, you can use your own recipes but only if you understand the principles that govern safe canning.

Adding Unapproved or Extra Thickeners When Canning

Don’t add thickeners when canning things like chicken pie filling. Instead, add thickeners right before using.

In the chicken pot pie filling example above, I mentioned the dangers of adding thickeners when canning.

Too much, or the wrong kind of thickeners, can make it more difficult for heat to penetrate the food you’re canning. Without proper heat penetration for the appropriate amount of time, botulism risk increases.

“Unapproved thickeners” extend beyond thickeners such as flour and cornstarch. Food such as rice, noodles, barley, and dumplings should be avoided. If you want to include a starch such as noodles in a canned soup, wait until you plan to serve the item to add the starchy item.

The exception to this is that it is safe to add potatoes to soups and other canned items when pressure canning.

There are also approved thickeners that can be used for canning such as Clear Jel, which is typically used in fruit pie fillings. It’s important to note that just because Clear Jel is an approved thickener for canning doesn’t mean that you can add it to any canning recipe, or use it in any amount.

Not Adapting Canning Recipes for Altitude

Adapting canning recipes for altitude is an important part of canning safely.

Altitude impacts both pressure canning and water bath canning. Most canning recipes are based on altitudes of lower than 1,000 feet or 305 meters above sea level. If you are in an altitude higher than that, you must adapt canning recipes based on your altitude.

With pressure canning, you adapt recipes by adding more pressure. For instance, in a lower altitude, when using a pressure canner with a weight, you would use a weight for 10 pounds of pressure. If you’re canning in an altitude above 1,000 feet, you need to use 15 pounds of pressure.

You also need to adapt water bath canning recipes if you’re in an altitude higher than 1,000 feet. For instance, if you’re between 1,000 feet and 3,000 feet, you need to add an additional five minutes of processing time to water bath recipes.

The reason this matter is because water boils at a lower temperature in higher altitudes. It’s important to adjust canning recipes for altitude because if you don’t, the food you’re canning won’t be processed long enough to kill microorganisms.

Pro tip: To gain a better understanding of how altitude impacts canning, be sure to check out my article, How Altitude Impacts Canning | How to Adapt Canning Recipes Based on Your Altitude

Hurrying Up the Cooling Process

All canning recipes include the appropriate amount of processing time. For instance, according to the National Center for Home Food Preservation, the processing time for canning beans is 75 minutes for pints and 90 minutes for quarts.

It’s important to note that this processing time takes into consideration the time that heat and pressure remains in the canner during the time when the canner is cooling down. You may have noticed that until the pressure drops, you’re unable to open the lid on the canner.

If you’re in a hurry, you may be tempted to remove the pressure weight (or in the case of the Nesco canner, turning the pressure valve from airtight to exhaust). Removing the weight does indeed cause the steam to shoot out of the canner much faster.

While I understand the temptation to hurry up the cool down process when canning, doing so results in your canned food being under-processed, and thus unsafe.

It can also cause siphoning (liquid coming out of the jars). In some cases, the rapid change in temperature may also cause jars to break.

Because of this, it’s important to allow the pressure to come down naturally before attempting to remove the canner lid. In my experience, this takes anywhere from one hour to 90 minutes.

Since the time that it takes to come down from pressure naturally is often as long as the actual canning process, it’s important to take that amount of time into consideration before starting a canning project.

As an example, I don’t pressure can anything unless I’m going to be home for at least three to four hours. I also don’t start canning anything when I’m hoping to go to bed within the next couple of hours.

Pressure canning is a time-consuming process, and it’s best to do it when you’re not in a hurry.

Using the Wrong Type of Canner

There are essentially three types of canners that are approved for home canning:

Each of these types of canners are to be used in specific ways, for specific types of food.

Pro Tip: To better understand the difference between pressure canners and water bath canners, read my article, Pressure Canning Vs. Water Bath

Both water bath canners and steam canners can be used for high acid foods such as fruit. It’s important to use pressure canners for low-acid foods such as beans, meat, and most vegetables.

Some people swear that you can use water bath canners for low acid foods such as the ones mentioned above. This topic arises a lot from both people in the United States who only have water bath canners, as well as from people in Europe, where pressure canners are hard to come by.

It is true that you can safely water bath can low acid foods. However, it’s not nearly as safe nor as convenient as pressure canning.

RoseRed Homestead

In this video, RoseRed Homestead demonstrates the folly of attempting to use a water bath canner for canning low-acid foods.

In the video, Pam (RoseRed Homestead) explains the algorithm used by the food industry to determine the temperature needed to kill botulism spores. She used that information to figure out how many hours it would take to safely water bath can low-acid foods. Here’s what she found:

  • For those at sea level, you would need to water bath can low acid foods for a minimum of six hours
  • At a higher elevation, such as 5,000 feet, you would have to water bath can low acid foods for a minimum of 18 hours

You have to ask yourself if you really want to process food in a water bath canner for so many hours, when you can safely process the food in a pressure canner for much less time.

Pressure canning is the safest and most efficient way to get foods into the kill zone when canning so that the risk of botulism is decreased, if not eliminated completely.

Using Pressure Cookers Instead of Pressure Canners for Canning

There can be a lot of confusion when it comes to understanding the difference between pressure cookers and pressure canners.

There are a few differences between pressure canners and pressure cookers. Once you understand those differences, you can see why pressure cookers aren’t safe for pressure canning.

The first difference is size. Pressure cookers are often smaller than pressure canners. The size difference matters because with a smaller size, both the heat up and cool down times are less in pressure cookers. This causes a similar problem under the point related to speeding up the cooling process mentioned above.

The shorter processing time can result in under-processed food, which can lead to botulism.

The other difference between pressure cookers and pressure canners has to do with regulating the amount of pressure. Pressure canners have weights that regulate the amount of pressure during the entire processing time.

The Nesco Smart Canner has a similar mechanism in that it has two different valves available, one for 10 pounds of pressure for those in a lower altitude, and one for 15 pounds of pressure for those in altitudes above 1,000 feet.

The weight (or in the case of the Nesco, a valve) is missing on pressure cookers, and because of that, they don’t maintain the right amount of pressure during the processing time. Without the weight or valve, it’s impossible to ensure that your food has been processed long enough and because of that, it’s unsafe.

Adding Extra Vegetables to Salsa Canning Recipes

Peppers and onions are a delicious addition to salsa, but when canning adding extra onions and peppers can throw off the acidity level, and make the salsa unsafe for canning.

If, like me, you like to wing it when you cook, when canning, you may be tempted to throw in extra onions, peppers, and other vegetables to salsa recipes.

As an example, let’s say that you’re using this salsa recipe on the Fresh Preserving site. In addition to vinegar and a few other ingredients, the recipe calls for 10 cups of cored, peeled tomatoes, 5 cups of seeded bell peppers, 5 cups of chopped onions, and 2 1/2 cups of seeded chili peppers.

Perhaps you really love onions, or you want more heat that comes from peppers. Is it okay to add extra onions or peppers? Or maybe you like corn in your salsa, and want to throw in a couple cups of corn. Is it safe to do that? In a word, no.

The reason for this is that most salsa canning recipes are water bath recipes. As such, they require the food you can to be high-acid. In the case of this salsa recipe, both the tomatoes and the vinegar provide the right amount of acidity to make this recipe safe for water bath canning.

If you add additional low-acid foods such as corn, or more peppers and onions, you risk decreasing the level of acidity, and thus make the salsa unsafe to water bath can.

Especially if you’re newer to canning and don’t know how to safely adapt recipes, for safety reasons, it’s best to stick with approved canning recipes.

Water Bath Canning Tomatoes without Adding Acid

Add acid when water bath canning tomatoes.

Tomatoes are often water bath canned. This is true when it comes to water bath canning salsa, canned tomatoes, tomato sauce, and so on.

One reason it’s safe to water bath can tomato-based recipes is because of the acidity level. However, the acidity level in tomatoes varies. If the acid level is too low, botulism can occur.

The good news is, it’s easy to add acid to tomatoes. You can add lemon juice, citric acid, or vinegar when canning tomatoes.

Check out the table below to know how much acid to add when canning tomatoes.

Acid TypeJar SizeAmount
Lemon JuicePint1 Tablespoon
Lemon JuiceQuart2 Tablespoons
Citric AcidPint1/4 Teaspoon
Citric AcidQuart1/2 Teaspoon
5% Acidity VinegarPint2 Tablespoons
5% acidity VinegarQuart4 Tablespoons

Pro tip: If using citric acid, be sure to use food grade citric acid such as this Ball Jar Citric Acid on Amazon.

Note that vinegar impacts the taste of the product more than lemon juice or citric acid, so I personally recommend only using it if you really like the taste of vinegar or if you have no other choice.

Allowing Food to Cool Before Canning

When you look at the canning recipes or instructions on sites such as the National Center for Home Food Preservation, you’ll notice that the instructions often include the words “hot pack” or “cold pack.”

What this essentially means is whether the product you’re canning is hot or cold when you put it into the jars. If the chart or recipe you’re following calls for “hot pack” the assumption is that the food is hot when you put it into the canner. The processing time in the recipe is based on that assumption. So, if the food you’re putting into the canner is cold instead of hot, the food may not process completely, and thus will be unsafe.

Follow Instructions to Can Safely

The bottom line is that home canning can be done safely, and following instructions from trusted sources helps ensure you don’t make potentially deadly canning mistakes.

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Here are some of my favorite canning tools

Thank you for reading this article. I hope you found it helpful as you strive to stock your pantry with delicious home-canned food! Here are some tools that I use as a canner that I’m hoping you’ll also find helpful. These are affiliate links, so if you do decide to use any of them, I’ll earn a commission. Please know that these are the tools that I actually use and recommend and believe in 100%!

Nesco Smart Canner: You can see that many of the posts on my site show me using the Nesco canner. This is by far my favorite canner to use, and because of that, it’s the one that I recommend. Note that the Nesco and Carey Smart Canners are the exact same thing. So, if you go to Amazon and see that Nesco canners are out of stock, but the Carey is available (or cheaper!), then by all means buy a Carey. As long as you have either a Nesco or Carey, you can follow along with what I demonstrate on this blog.

Tattler Reusable Lids: I use both Tattler and Harvest Guard reusable canning lids. They are both American made, made by the same family. I prefer to buy my Tattler lids from Lehman’s, since they are a small, family-owned company. You can get Tattler lids from Lehman’s here, but if you prefer to buy from Amazon, you can get them here.

Metal Canning Lids: I have always been a fan of Ball canning lids. However, due to cheap knock offs on Amazon that claim to be Ball lids, I no longer purchase them from Amazon. You can get them from Lehman’s here. Another solid brand that Lehman’s sells is Superb. They are thicker and seem to have better quality gaskets. Here are the regular mouth lids and here are the wide mouth lids.

Norpo Canning Tools Boxed Set: I love this set of canning tools because it truly includes all the basics that you need, whether you’re water bath or pressure canning. Occasionally I’ve lost one of the items in the set and to replace it, had to buy it separately. It’s definitely more cost effective to buy the entire set.

The Ball Complete Book of Home Preserving: This is the first canning book that I purchased, and it’s still the one that I refer to most often. Especially when you’re first learning to can, it’s important to use trusted recipes and instructions that you know are safe. This book provides some great canning recipes to get you started, and also gives a lot of great “how to” canning information. When in doubt, look it up in the Ball Complete Book of Home Preserving!

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