Why We Sometimes NEED To Pressure Can

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The last time I gave a presentation on pressure canning, I made a mistake somewhere. I don’t know what I did wrong, but when I later ran into one of the attendees, and asked if she had started canning yet, I got a surprising answer. She gave me a very embarrassed look, and simply said “you scared me out of it; I’m going to dehydrate instead.”

I was baffled by that statement. My goal was not to scare anyone away from preserving food, but to teach the proper and safe way to do so. There are after all health risks involved. And as most preparedness minded people suspect, healthcare services may be greatly reduced in the future, so preserving food in a safe manner is important. So I’m going to try to give you the important info you need when it comes to pressure canning. But don’t let this information deter you from pressure canning. Pressure canning is an absolutely wonderful way to preserve food.

One of the most common statements I hear when it comes to canning is “don’t change the recipe”. But no one can ever answer me when I ask why you would not change the recipe. We’ve become accustomed to following our grandma’s favorite recipe, and fear for unknown reasons why we would not change it.

My goal here is to tell you why you don’t want to change the recipe, and to also give you the knowledge of what you can do in a situation where you have no choice but to change the recipe, because of lack of ingredients. While following recipes is fine, having an understanding of why we do something a certain way, gives us the power to control our situation when we have to.

There are different methods of food preservation, but when it comes to canning, there are mainly two techniques, though some folks might want to tell you about other ways. For your and your families safety, stick with the two well tested over time methods. The two recommended techniques are water bath canning, and pressure canning. I am not referring to other storage methods to kill general pests on grains.

I am referring to pressure canning low acid foods. Here is an article that tells you how to water bath can and what you can and shouldn’t water bath can.

Also, here is how to water bath can without electricity.

And here are some things you should not do.

Simply put, pressure canning takes a lot of energy, which isn’t always necessary, nor do we always have that extra energy. Generally, water bath just means that you submerge your jars filled with food to be preserved for a certain amount of time while the water is boiling. This method usually means the contents of the jar reach 212 degrees Fahrenheit. Unfortunately, there are some bacteria, one in particular I’ll mention shortly, that are not killed by this process. It’s just not hot enough to disable the bacteria because it needs to get to a minimum of 240 degrees Fahrenheit.

Clostridium botulinum is your enemy when it comes to food preservation. This bacteria thrives in moist and oxygen free environments, which sounds a lot like the inside of a jar of home canned food. The neurotoxin that this bacteria produces is responsible for botulism poisoning, which can lead to months of treatment, assuming you live through it. If no antitoxin is available, victims must be hospitalized and placed on a respirator. Even if treated quickly, depending on severity, full recovery may take years

Worse yet, the bacteria that produces this toxin isn’t killed with standard temperature in water bath canning. Thus, we turn to the pressure canner to solve this problem.

The good news is, we’ve done such a good job at proper food preservation by following recipes to a “T” that cases of botulism poisoning are quite rare. However I fear this will change when more people have to resort to home canning for food preservation, which is what prompted me to write this.

Like Russian Roulette, botulism poisoning isn’t something you want to take chances with. It’s one of those things that I’d rather be overly cautious with, than be regretful later that I didn’t take one extra step. It takes less than three molecules of botulinum toxin to result in poisoning, and a teaspoon of food has millions of molecules. In fact, according to Wikipedia and JAMA, “It is the most acutely lethal toxin known, with an estimated human median lethal dose (LD-50) of 1.3–2.1 ng/kg intravenously or intramuscularly, and 10–13 ng/kg when inhaled.” Scientists even claim that one gram could kill millions of people.

I am ever so thankful that our ancestors have learned a way around such problems. The bacteria clostridium botulinum is easily destroyed by higher temperatures, which can be achieved by the process of pressure canning. Basically, a pressure canner results in a sealed environment that prevents heat from being able to escape, and allows the heat to build up. As the molecules move faster within the canner, the temperature gets higher as the pressure builds up. According to the Presto pressure canner manual, at five pounds pressure, the temperature is 228 degrees Fahrenheit. At 10 pounds pressure, 240 degrees, and at15 pounds pressure, 250 degrees Fahrenheit. Now that’s hot enough to kill the botulism bacteria and its spores. But note, there are differences in temperature based on elevation, so make sure you are following that manual!

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But wait! This gets even more complicated! There is also a time factor involved. How long do you keep the contents under such high heat and pressure? Several factors make a difference here. Elevation, jar size, and contents all matter. Yikes, it’s too much to keep track of! Not really. Most pressure canners come with a general manual, follow that and you should be fine. If in doubt, go the maximum time at the maximum elevation and maximum jar size; that is always a safe bet. Lost your manual? No problem. Get tested recipes for free here.

Even more good news! Got a canned jar of green beans as a holiday gift? Not sure you trust how they processed the food? Would hate to see that good food go to waste? I have a solution for you. Boil the food for a minimum of 10 minutes. I personally boil for 20 minutes, but I overdo things sometimes.

The toxin that is produced can not handle boiling temperatures for extended periods of times. If you boil your food for a minimum of 10 minutes, you should be safe. Note that boiling the food directly in cooking has a different effect than the boiling used in water bath or pressure canning. In the case of cooking the food, you are destroying the botulinum toxin, but not the actual bacteria. In the case of pressure canning, you are actually killing the botulism bacteria which produce the botulinum toxin so that they can not continue to live and produce the toxin. So if you cook the food to destroy the toxin, you need to eat it right away before the bacteria can produce more of the toxin.

Even better news about botulism: The pressure canning requirement only applies to low acid foods. That means that most fruits that have a high acid content don’t need to be pressure canned. In such cases water bath canning is more than enough, and adding acid (such as vinegar) to recipes can create an acidic environment that the bacteria doesn’t like. So while the botulinum toxin is stable in acid, the botulism bacteria does not like acidic environments and will not reproduce or produce the toxin while in such an environment. Aha! That’s why you don’t change a recipe: for fear of changing that darned pH level of food. If a recipe says to add one cup of vinegar then add a full cup already! Here is a handy chart of different levels of acidity based on food.

Notice that tomatoes are borderline and should be treated as an alkaline (low acid) food.

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Why not just pressure can all our food at maximum temperature? Well, outside of the energy required, some of us like our food to have flavor rather than taste like water. It’s just reality that pressure canning takes a lot of energy and greatly reduces the flavor of food. But in a worst case scenario, where you have to preserve your food and your manuals have all burned down in a fire, remember what the maximum requirements are for the largest jar size at your elevation, and how long to can them for, and just do that with all low acid foods. Yep, just memorize the maximum amount of required pressure and length of time, and you’ll be fine. Your food might not taste the greatest when you’re done with it, but at least you know you won’t die from it. Again, if in doubt, boil that food for 20 minutes just before eating, as a secondary safeguard to make sure you and your family don’t end up dying from paralysis due to botulism poisoning. SHTF is going to be hard enough, no reason to make it any tougher.

Oh, and if you do end up finding botulism, it seems there’s quite a market for it: http://www.webmd.com/beauty/botox/botulinum-toxin-botox

Yes, I do always try to find the bright side in things.

And if I managed to scare you away from pressure canning (hopefully not), you can always dehydrate food instead.

About Paylie Roberts

Paylie Roberts is the author of the recently published non-fiction book Memories of Poland, Lessons From Growing Up Under Communism. She is also the author of two novels: Bugging Out To Nowhere, and Life After Bugging Out. She has a Bachelor’s degree in biology, and lives with her husband, two German shepherds, and various livestock, somewhere between the Cascade Range and the Rocky Mountains.

View all posts by Paylie Roberts

2 Responses to “Why We Sometimes NEED To Pressure Can”

  1. Miriam Says:

    This is a very good article but the big question – and one you said you would answe in this article is “why not change the recipe”. Either I missed it, you were too subtle for me, or it’s not there. Could you answer that question?


  2. Paylie Roberts Says:

    Changing the recipe can change the pH which can change the requirements of pressure canning vs water canning, as well as the time it takes to effectively complete the canning process.


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