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, people diets radically changed. As they 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.
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.
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.