Once upon time, I thought I was the Invincible Canner.
Oh my, anything I could put in a jar and seal was a success. Astounding! I was invincible! Unbeatable! Indomitable! I could can... ANYTHING!
Take refried beans, for example. My family eats a fair bit of refried beans. They're easy to make, but rather time-consuming; and it bugged me to buy cans of refried beans at the store. So, being the Invincible Canner that I was, I concluded I would can my own refried beans.
This turned out to be much more challenging that I thought.
But I finally succeeded and proved -- told ya so! -- that I was the Invincible Canner.
Therefore it was annoying to get a comment on my Refried Beans blog post from a Master Canner (with actual bona fide credentials), informing me that refried beans were too viscous to safely can at home because home-canning equipment is not sufficient to render this food safe.
What was she talking about? My jars sealed just fine, thank you -- didn't she know I was the Invincible Canner? Who was I, goddess of the pressure canner, to listen to this mere mortal, just because her qualifications exceeded my own?
So when the Invincible Canner decided to write some inexpensive ebooklets on canning in order to share my passion for this science with lots of others, I invited everyone to send me their basic canning questions so I could be sure to address them all.
And then the research started. I'd been canning for over twenty years and thought I knew it all. Boy was I wrong.
This research gave me a Master Canner education (without the credentials) and taught me an astounding amount of information I didn't know before. Who knew, for example, that milk products were unsafe to can? And fats, such as lard? And -- oh shucks -- the list of unsafe viscous foods included refried beans. Crud. My critic was right.
In short, this research toppled me off the Invincible Canner pedestal I had put myself on, and knocked some humility into me. And humility, as anyone knows, can be painful to acquire.
One of the things I learned is just because a jar seals does NOT mean the contents will be safely preserved for all eternity. Botulism is an insidious little bugger, and it can lurk in foods with certain chemical compositions regardless of whether a jar has successfully sealed.
That's why it's important to consider research done by such organizations as the U.S. Department of Agriculture, which does exhaustive research and testing on safe canning procedures. Normally I wouldn't trust a government agency any farther than I could throw it, but I trust the USDA to give reliable guidelines for canning. In other words, I don’t think the government is trying to undermine our self-sufficiency efforts by advising us not to can puréed pumpkin -- know what I mean?
I hear far too many people say, "I've always done it this way and I've never gotten sick" while trying to justify unsafe canning procedures. And you know what? They're right. People drive for years and years in perfect safety without wearing a seatbelt...until they get into an accident. People smoke for years and year in perfect health... until they get lung cancer. People can for years and years in perfect safety using unsafe canning procedures... until they get botulism.
This is why I trust the USDA's guidelines for what constitutes safe canning procedures over anyone's "I've always done it this way and I've never gotten sick" experience. Past performance does not guarantee future results.
I don't mean to sound like a know-it-all when it comes to canning; I'm merely saying that I learned a whole lot while writing these ebooklets, and I've revised my own canning techniques as a result. I'm also begging people to be safe. Canning is a remarkable science, and it's also become one of the most researched subjects in the food industry. That's why guidelines are continually being updated.
Here is the portion on what isn't safe to can from my ebooklet Canning FAQs: 100 Basic Questions about Canning. I harvested this info from many different sources, but it's all confirmed by USDA guidelines:
51. What should NOT be pressure canned?
There are some things that home canners shouldn’t can at home, even with a pressure canner, and even if those products are available commercially. Commercial canneries have additives, preservatives, and processing controls not available to home canners. They also have professional processing equipment which we can’t duplicate at home.
The foods not recommended for home-canning include:
• Foods packed in oil. Canning in oil is not recommended because oil coats and insulates botulism spores and creates an anaerobic micro-environment which allows the spores to survive high heat. To kill botulism spores encased in oil would require pressure canning at such high temperatures and for so long that the food itself would be destroyed. (A small amount of oil, for example sautéing before canning, is acceptable.)
• Highly viscous foods. Items such as refried beans, peanut butter, pumpkin purée, or squash purée should not be home-canned. (Cooked cubed pumpkin can be canned at home, but cubed squash will compress during heating and become too thick; it should not be home-canned).
• Lard. Too dense and too fatty to safely can at home.
• Pickled eggs. Too dense to safely can at home. There are no tested recipes for canning pickled eggs.
• Dairy products. Soups (or other foods) made with cream, milk, butter, or other dairy products are not recommended for home-canning. Like oil, dairy products are low-acid and support an environment which fosters botulism growth at room temperature. The fat in dairy products can protect botulism spores and toxins from heat during the canning process. When milk is over-heated, the milk proteins drop out of suspension and separate. The amount of heat that would need to be used to kill botulism is so extreme that the food would be rendered inedible. For this reason, canning milk or canning butter is not recommended as a safe procedure for home canners.
• Cornstarch. Cornstarch is a thickener which breaks down during processing; more importantly, it retards heat penetration. For thickening agents, use Clear-Jel, which is a modified corn starch formulated for canning. Clear-Jel does not break down in acid food mixtures, and it does not thicken so much that it interferes with heat-killing of pathogens. Please note that processing times listed in published reference books are not sufficient for using any thickeners other than Clear Jel. Unfortunately this product generally can’t be found in grocery stores. Some online sources include:
- The Ingredient Store www.theingredientstore.com
- Kitchen Krafts www.kitchenkrafts.com
- Walton Feed www.waltonfeed.com
• Flour. Some people believe they can make “cakes in a jar” or other foodstuffs which contain flour. This is strongly inadvisable. Home canned flour products (breads, doughs, etc.) are considered very prone to botulism. No one has yet been able to come up with a reliable recipe and canning direction that doesn’t produce botulism some of the time. Flour products are low-acid and “baking” them in a jar is not “canning” and is not recommended.
The reasons behind the inadvisability of canning these foods are generally due to one of two things: either scientific research has demonstrated that home-canning of such foods is potentially hazardous; or the only way to can them is at such high pressures that the results are unpalatable. In other words, if it’s not possible to kill off botulism spores while producing a palatable product, then the food is placed on the “not recommended” list.
There will always be people who think the rules don’t apply to them, or believe they’re special enough to refute the science behind safe canning. This is the kind of sloppy canning techniques I continuously warn about. Remember, past performance (“Granny always did it!”) does not guarantee future results. Canning is a highly developed science, and to assume the rules don’t apply to you is asking for trouble. Be safe.
Now of course, I'm not the Canning Nazi. Whatever you do in your kitchen is your own business. If you choose to water-bath tomatoes with low-acid ingredients like onions and bell peppers "because granny always did it," fine. If you don't think the USDA guidelines are worth following, I won't agree; but I won't argue either. If you believe you can refute the USDA guidelines because you, too, are the Invincible Canner, then so be it. Just don't say I didn't warn you.
I am passionate about canning because I believe it is one of the most remarkable ways to preserve food on this earth. It gives me tremendous pleasure to share and invite canning stories, tips, recipes, and advice. But at least on this blog, I will always try to post advice that's backed up by science.
I no longer believe I'm the Invincible Canner. I now know there are things that are not safe to can in my beloved All American pressure canner. And since I want my family to be able to depend upon me to provide food that is safe to eat, I won't can up things the USDA specifically advises against.
Now let the arguments begin...