Kimchi is a ferment commonly associated with North and South Korea. It can be very spicy or not, depending on your taste, and is usually based on Napa cabbage with a number of other vegetables thrown in. The chopped veggies are brined and then mixed with a paste of garlic, ginger, onion, red pepper, fish sauce and a little sugar, and allowed to ferment at room temperature until desired funkiness is reached. Then it can be refrigerated to slow everything down to a glacial crawl.

The microbiology is similar to what’s happening in sauerkraut, with the added fun and funk of fish sauce or shrimp paste, and lots of garlic and ginger. It’s absolutely possible to make a vegan kimchi, omitting the fish sauce or shrimp paste. The flavor will be different but still delicious; more like a kimchi-kraut.

The Napa cabbage and other vegetables (radish varieties, turnip, spring onion, red onion, any brassica, red pepper, carrot…) provide the microbes that start the fermentation process. Brining the vegetables deters pathogens, and so does excluding oxygen and decreasing pH due to the acid byproducts of the microbes. In this environment, beneficial bacteria and yeasts can happily ferment with wildly funky and delicious results.

Millions of local bacteria and yeasts cover the vegetable’s outer surfaces. We are also covered with the same microbiota (micro = small, biota = life), as are the inside surfaces of our gastrointestinal tract. Our insides are actually continuous with the outside if you think about it. Our microbiome is defined as the genetic material of the microbes inside us, but the words are used interchangeably. It’s grammatically and scientifically slightly erroneous, but whatever gets the message across…

When you slice and smash up the chosen vegetables for kimchi, you are exposing the insides of the plant cells to the microbiota on the outsides of the leaves, as well as those in the air and any equipment you are using. The bacteria and yeasts obligingly start to eat the sugars stored in the plant cells and give off heat, metabolic byproducts; acids and alcohols, and CO2. They eat and breathe just like we do. Though they are really really small, they will have the last laugh at all living organisms, because there are a WHOLE LOT more of them and when anything dies, the microbes on the outside get in and consume them, liberating the organic molecules bound up in the life form for consumption by other organisms. Ah, the circle of life.

If you look at a microbial timeline in a vegetable ferment of a particular salinity and temperature, you’ll see one organism initially predominate, creating an environment favorable for another to take over. In turn, they adjust the environment for others to proliferate and so on until a final pH, microbial and flavor profile stabilizes. It’s mostly lactobacillus species that does the job eventually. We taste it, say YUMMY! and put the whole thing in the fridge. The cooler temperature slows fermentation to a crawl such that your jar of kimchi becomes slowly more fermented, but likely you’ll eat it before it becomes unpleasant.

For nerding out purposes, The predominant bacteria in kimchi are genera Lactobacillus, Leuconostoc, and Weissella among many others. Basically, the Leuconostoc bacteria starts off and prepares the environment for takeover by Lactobacillus and Weissella creating a pathogen-free and tasty ferment very quickly. If it’s warm in your kitchen, you’ll have kimchi in less than a week. for a more complex and funky kimchi, you can continue to wait a few days, tasting as you go.

Similar to Sauerkraut, an anaerobic (oxygen free) and halophilic (salty) environment will allow Leuconostoc to start rapidly proliferating, creating a byproduct of acetic acid, lowering pH to create an environment that inhibits other pathogenic microorganisms, and encourage Lactobacillus and Weisella to do their kimchi thing.

food source + microorganisms ————— time ———————-> ferment

sugar in vegetable leaves on leaves, surfaces, 5-10 days kimchi!!!

and other ingredients equipment, in air at room temperature

Lets make some! Here’s the recipe.