What You Need to Know about Home Canning and Botulism

Recently, Rene from Faith, Farm, and Family Table typed to me: "I want so badly to can meat but I am terrified of poisoning my family...I know you just have to follow the process of pressure cooking, but is there any other major things I should know?" Rene's fear of pressure canning in general or canning meat in particular is incredibly widespread...but, like many fears we have, are easily dashed aside when hit with a good dose of facts.

Water Bath vs. Pressure Canning
The difference is important!

First, let's define some important terms, so we're all on the same page.

A water bath canner is a large pot with a loose lid. In fact, you can use any large pot for water bath canning, as long as it has a lid and a rack on the bottom that prevents the jars from touching the bottom of the pan.

A pressure canner is also a large pot, but it must be made for the specific purpose of home canning. It's lid fits tightly and has a pressure relief valve and a gauge that helps canners monitor the pressure inside the pot. It is not the same thing as a pressure cooker. (Although some pressure canners may also be used as pressure cookers, no pressure cooker can safely be used as a pressure canner.)

Okay, now that' out of the way, let's talk about not killing your family through home canning.

The Big Fear: Botulism

Botulism spores are nearly everywhere in our environment. When placed in a low-acid, oxygen-free, high-moisture environment (like a sealed canning jar), those relatively harmless spores grow into a toxin that kills without prompt treatment. (Even with treatment, patients may spend the rest of their lives with damaged bodies.) Botulism spores can't be killed by boiling, freezing, drying, most household cleaners, or even by radiation. As Erica Strauss of Northwest Edible Life has pointed out, just a single pint jar of pure botulism toxin would kill everyone on the planet. No wonder home canners are mindful of it.

Thankfully, botulism poisoning is rare. In the U.S., the Centers for Disease Control (CDC) receive about 145 reported cases of botulism poisoning yearly. Only 15% of these cases are associated with food. However, among those cases 38%, are from improperly home canned vegetables.

What Kills Botulism

There are two ways to ensure your home canned food does not kill somebody (or make them seriously ill). The first involves the acidity level of the food, and the second has to do with heating the food.

Botulism spores hate a high-acid environment. That means if your canned food is high enough in acidity, botulism can't make you sick. Foods that are safe to water bath can must have a high acidity level - 4.6 or higher. Anything below that level of acidity must be pressure canned, or indeed, it might make someone very, very sick.

(As an aside, the most common excuse for water bath canning low acid foods, like vegetables, is "But my grandmother did it and we're all still alive!" First, water bathing low acid foods was never the norm. Ever since home canning in jars became a thing in the 19th century, experts recommended water bathing only high acid foods. Second, that comment is rather like saying, "But I drive home drunk every night and I haven't gotten into an accident yet!" And, in fact, many people who water bath low acid foods do get sick. Not all food poisoning is botulism, after all, and most food poisoning is mistakenly thought a "24 hour stomach bug.")

So, to be clear, jams, fruits, fruit juices, and pickles made with the correct acidity are generally safe to water bath can. (But always check The National Center for Home Food Preservation (NCHFP) to be sure. Certain fruits - like white peaches - are not high acid.) Non-pickled vegetables and meats are low-acid and must be pressure canned to be truly safe. 

So why does pressure canning work with low-acid foods? Because it gets the temperature of the food up to 240 degrees F. (much hotter than the boiling water in water bath canning can every reach), and botulism spores can't survive that temperature. (Even then, however, that temperature must be kept for a certain length of time for the spores to completely die off.)

The Easy Way to Prevent Botulism Poisoning

Hopefully, now you can see why tested safe recipes - recipes that have been tested in a food science lab - are vital to safe home canning. Despite what some people say, home canners have no reliable way to test the food they are canning, nor do they have a way to know they've processed food long enough to kill botulism. 

When we hear about home canners giving themselves or others botulism poisoning, they've always made egregious choices. For example, in 2013, a Washington man nearly died of botulism after consuming elk meat he'd processed in a pressure cooker (not a pressure canner - first problem) for a far shorter time than he should have (second problem). When the lids started coming off his jars while in his pantry, instead of throwing the meat away, he ate it (fourth problem). In 1997, an Illinois man came near death after eating home canned pickled eggs. That's right; there is no approved home canning recipe for eggs of any type. And in 2015, someone poisoned a bunch of folks at their church picnic (killing one) by serving water bath canned potatoes. 

However, if you just follow a tested safe recipe, you home canned food is perfectly safe, as long as the seal remains intact.

As you become more experienced, you'll find you can change the spices in recipes like stew, or create your own soup using NCHFP's guidelines. But never change what type of canner you use, or how long the processing time is, or can anything the NCHFP or a current Ball book says shouldn't be canned. (That includes all dairy, eggs, grains, and anything so dense it can't be heated through - like pureed pumpkin or very thick applesauce.)

So how easy is that? Just use approved recipes from a source like Ball or NCHFP. Easy peasy!

Just in Case...

If you simply follow tested recipes, it's highly unlikely you'll ever get food poisoning from your home canned foods. However, there are a few other guidelines you should bear in mind:

* Never store your home canned food with the rings on. Sometimes jar lids unseal. If you leave the ring on the jar, it may reseal; bacteria will enter the jar, and you'll never know the food is contaminated. If you leave the ring off the jar, however, it will not reseal...so when you discover the open jar in your pantry, you will throw the whole thing away, rather than eat it.

* Don't stack anything (other jars, commercially canned food, etc.) on top of jars. Again, this can make lids open and reseal, just like keeping the rings on does.

* Store your home canned food in place where temperatures don't fluctuate and it is neither hot nor cold. (If you're comfortable, so are your jars of home canned food.)

* Pay attention when you open a jar of home canned food. If the seal isn't tight, don't eat the food in the jar.

* If you find a jar with a bulging lid, it is contaminated; don't eat it.

* If you open a jar and liquid or foam squirts out, the contents aren't safe to eat.

* Smell the food while it's still in the jar. If it smells off in any way, do not eat it.

* If there is any mold in the jar, toss the jar.

* If you do suspect any home canned food is spoiled, place the jar and food in a plastic bag, seal it, and dispose of it in the trash. Wipe up any spills with diluted bleach (1/4 cup bleach to 2 cups of water, according to the CDC).

Knowledge is power, my friends. And home canning isn't difficult. It is perfectly safe to use a pressure canner. Just use a trusted recipe!

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