Fermenting Versus Canning

Updated 06/11/17


noun     fer·men·ta·tion     \ˌfər-mən-ˈtā-shən, –ˌmen-\

“[The] process by which microbes consume sugars and produce acid, alcohol and gases.” — from The Good Gut

“The transformative action of microorganisms.” — from The Art of Fermentation

Often when I discuss fermentation, people say to me “Cool! I’ve always wanted to try canning.” Before I started fermenting food, I likely thought the terms fermenting and canning identified the same process (if I thought about it at all, which I probably did not). In fact, fermenting and canning differ completely.


A (Very) Brief History of Food Processing

For thousands of years, people have processed food through various fermentation methods. Submerge some salted cabbage in liquid and after a few days, you have tangy sauerkraut. When mixed together, flour and water will bubble into a yeasty starter for baking mouth-watering sourdough bread. Honey and water transform into delicious mead with a pretty impressive alcohol content (let’s say low double digits). Through fermentation—and other methods of food preservation, such as salting, smoking and drying—people “put up” food to get them through winters and lean harvests.

In the 19th and 20th centuries, Western diets radically changed. As people moved away from farms to cities, they also moved away from fresh produce. Without access to fresh food, what would they eat? As Harold McGee writes in his classic On Food and Cooking, technology came to the “rescue”:

This situation was alleviated to some extent by the development of rail transportation, then canning around 1850, and refrigeration a few decades later.

These developments made industrialized food possible.

Nutrition and Health

The process of canning—a fairly new development—involves sterilizing food in hermetically sealed containers. I used to make delicious plum jam. I filled mason jars with my jam, placed the jars in a huge pot (called a kettle) filled with water and boiled the jars for about fifteen minutes. The heat kills any harmful bacteria in canned food, making it safe to store at room temperature. The heat also kills all beneficial bacteria. (Low-acid foods such as beans and corn must be canned in a pressure canner, according to the USDA and CDC.)

The good bacteria present in fermented foods offer all sorts of benefits. Fermented vegetables contain higher levels of B vitamins, such as thiamin, riboflavin and niacin, and fermentation preserves vitamin C. Phytates in grains, nuts, seeds and legumes bind to minerals, making nutrients unavailable for absorption. Fermentation breaks these bonds so the body can absorb the previously unavailable nutrients. Eating fermented food also helps maintain a healthy gut. Get your hands on a copy of The Good Gut for a fascinating read on the importance of gut health. (You can read my review of the book here.) Your gut health is responsible for, well, everything it turns out.

In my own life, eating more fermented food has made a huge difference in my health. I used to catch every bug circulating and today I simply do not get sick. My younger daughter eats very little “weird” fermented food and still gets sick but I never catch it. I also feel less anxious. I had chalked that up to aging and wisdom until someone pointed out to me that I eat an awful lot of fermented food. Many recent studies show a connection between the gut and anxiety, depression and even autism.

kraut source hot peppers
My latest ferment: hot peppers using my new Kraut Source fermenting device


The anaerobic bacterium Clostridium botulinium thrives in airless containers. When this bacterium takes hold, it produces the nerve toxin that causes potentially fatal botulism. Botulism symptoms include “double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth and muscle weakness” (CDC). However, before you toss your canning equipment, do know that food-borne botulism has sickened only 210 people in the US between 1996 and 2014.

Even with these low numbers, people often tell me they worry about accidentally killing their loved ones by feeding them botulism-laced fermented food. But as Sandor Katz writes in The Art of Fermentation, “it is improperly canned foods, not ferments, that can harbor botulism.” Hardy botulinum spores can survive the canning process, however, they can’t survive the acidic environment of fermented food, nor can Salmonella, Escherichia coli (E. coli) or Listeria.

Food Preservation

Although fermented food has a long shelf-life, canned food lasts even longer—years and years. The refrigerator will slow down fermentation but it won’t stop it. Eventually your ferment will taste too sour for your liking or it will simply rot. So if the apocalypse hits, you can bet I’ll kick myself if I have no canned tomatoes. But until then, I’ll continue to enjoy my fermented food.


Canning requires a lot of energy to boil the water, whereas fermented food seems to magically cook itself. Many ferments require no cooking or heating at all. However, without a cool basement or cold cellar, I do store most of my finished ferments in the refrigerator, which does consume quite a bit of energy. Canned food can sit on a shelf at room temperature indefinitely.

Fermentation requires very little of our energy to prepare. To brew kombucha, you brew tea, sweeten it, backslop a bit of kombucha from a previous batch, add the SCOBY and wait. To ferment vegetables, you chop them, salt them, pack them in a jar and wait. Some dairy ferments require even less work. To make kefir, you add some kefir grains to milk and wait. I think the “and wait” step has (in part) led to a demise in people fermenting food. Not that people can much either—or cook at all. Our addiction to convenience has rendered most of us helpless. But that is thankfully changing.

The kids complain about having a kombucha-only fridge but you can clearly see we have plenty of food!

23 Replies to “Fermenting Versus Canning”

  1. It is not possible for there to be botulism in foods that are hot water bath processed – the jams, jellies, pickles and fruits, because the acid content in those foods are too high. However, botulism can be a threat in low acid foods (vegetables, meats, broths) which should only be pressure canned. Pressure canning can seem daunting, but newer pressure canners are fairly easy to use and once you learn how to use your pot, you’re set. They don’t use as much water as hot water bath canning, but it’s not recommended you use the pressure canner for items you would hot water bath – it reaches a much higher temperature, which affects the texture of the food you are preserving. It’s fantastic though for putting up broth. I do love having jars of homemade broth on the shelf, ready to go when I want them.

    It inevitably happens someone in my canning classes thinks they’ve signed up for a fermenting class and I end up spending a huge chunk of time trying to explain the difference to them. Because I do both, I can explain it, but the concept can be hard for people to wrap their head around.

    1. Thanks for the info, Becky. I would love to have some canned broth on hand. That sounds ideal!

  2. I just picked up a copy of the Good Gut yesterday based on your recommendation. Looking forward to a good read! Thanks for another great post A.M.

    1. Great Karen! Let me know how you like it 🙂

  3. I started the Good Gut, it’s a really fun read!

    1. Isn’t it great?! I’ve told everyone I know to read it. We’re eating all the wrong stuff!!! (Most of us anyway…) The information all makes such sense. I’m glad you’re enjoying it 🙂

  4. That’s an inspiring summary. Do the Kraut Source lids make a lot of difference for you?

    1. Thanks Aggie 🙂 So I am always able to come up with some sort of trick to keep the vegetables submerged. I usually put a cabbage leaf in the jar over the kraut and then a smaller jar on top of the cabbage. When I screw the lid on top of the jar, it shoves everything down. But I have to say this is a great little gadget and I’m going to get a lot of use out of it. This is the first time I’ve tried it and it works very well.

  5. I like your new device. And thanks for a very clear explanation of the fermenting process. I get a little weary of explaining it to my guest – I will refer them to this post in the future.

    1. Thank you so much Hilda 🙂 It’s a handy little device. The company sent it to me to try (I am not getting paid to write about it) and it takes care of submerging everything. I find that’s pretty much the only trick to fermenting successfully, keeping it all down in the jar.

  6. Thank you so much for this story! I’ve always been intimidated by the idea of canning and prefer the refrigerator pickles, kimchi, sauerkraut anyway. I always thought maybe I should finally knuckle down and figure out the other method but you’ve provided a very good reason to continue my easy, tasty ways of preserving veggies instead! PS, I am absolutely obsessed with these sweet golden beet pickles I made last month. They were soooooo good–sour is great but, man, a good sweet pickle is just super yum. 🙂

    1. You’re welcome, Lori. I’m too lazy to can 😉 I have to try making some of those pickles. You mentioned those before and I thought they sounded delicious. How did you make them?

      1. OK, so first of all you are *not* lazy and second of all, I finally found the recipe (I tore out the page & didn’t note which magazine!) I think it’s this one from Martha Stewart: http://www.marthastewart.com/1125582/sweet-pickled-shaved-golden-beets . I especially like that it lasts so long. I’ve been digging into the jar for weeks now and have to find another local organic vendor of golden beets very soon!!!

      2. Thank you on both counts Lori 🙂

  7. Great article!

    One thing you might be aware of for your workshops: Fermented foods contain a lot of histamine, which can cause problems for some people. I had been fermenting like crazy, but began having headaches whenever I ate fermented food. Kombucha, in particular, whether made by me or bottled, gives me a headache instantaneously. It got worse and worse, and then things like yogurt, and even non-fermented, high-histamine foods like tomatoes and avocado were causing headaches. I did some research and found that the histamines in fermented foods can trigger headaches, hives, and other problems for some people, particularly if their entire diet is high-histamine, or they have another allergy that is causing their body to release histamine.

    Interestingly, probiotic supplements don’t usually contain histamine (it’s a bacterial by-product, and in probiotics, the by-products are removed), so they are usually okay.

    The whole thing frustrates me, because 1. I love fermented foods, 2. I love fermenting, and 3. some part of me suspects that it is all due to a gut-microbe imbalance, but I sure can’t take the “cure” if the “cure” is eating more ferments!

    1. Thanks for the info Sadie. I will look this up. Fortunately I have yet to meet a ferment that doesn’t agree with me. That’s a bummer you can’t eat them 🙁 I hope you can heal your gut (if that’s the problem…I would be willing to bet money on it) and enjoy them again.

  8. Hi there. Sorry, I thought I responded to this. That sounds awful–the headaches and not being able to eat the foods you love 🙁 If the problem is a gut-microbe imbalance, I hope you can fix it and then enjoy your ferments again. Thanks for the info.

  9. Michele Sharik says: Reply

    I use a steam canner instead of a water bath canner. Same results and uses so much less water!

    Here’s a link to more info (and it includes a link to the UW Extension that studied the safety of steam canning vs water bath canning):


    1. The Zero-Waste Chef says: Reply

      Thanks so for much for this info. It looks like a great resource. I have heard from several people who have steam canners and they love them.

  10. This is so informative! I personally enjoy fermenting better, as you get all the healthy probiotics at the end of the ferment. Canning kills all of them! Thank you for sharing.

    1. The Zero-Waste Chef says: Reply

      I’m with you Billy. Fermenting is so healthy (and delicious!).

  11. Jackie Schemenauer says: Reply

    So informative as always! I have been using the terms interchangeably. Now to see if the old glass lids for madon jars are ok with fermenting.

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