Kimchi is the universe. It’s the cosmos. It’s life,” declared Susan Park. The Seoul native and Korean food historian based in Los Angeles chuckled as she said this to me, an acknowledgement that no words can adequately sum up the eminence of kimchi’s role in Korean cuisine and culture.
Behind the Recipes
The Art and Science of Korean Kimchi
Korea’s age-old tradition of preserving napa cabbage with salt, gochugaru, and garlic is one of the world’s greatest lessons in lacto-fermentation and community.
By and
Published Aug. 6, 2024.
Kimchi is the universe. It’s the cosmos. It’s life.
Indeed, the making and sharing of it, an age-old ritual known as kimjang, is a marvel of humanity, a sacred act that bands people together—whether it’s an entire village in rural South Korea preserving acres of vegetables to sustain itself over the long, harsh winter or a small family working through a case or two of cabbage in an apartment kitchen thousands of miles from the mother country.
Savoring kimchi’s communal vibe and its sour, funky character is restorative, a way to connect with one’s roots from anywhere.
Kimchi is a marvel of science too. The many hands that start the preservation process eventually pass the baton to lactic acid fermentation, which ushers the vegetables along a dynamic journey that makes the ferment safe to eat indefinitely, as well as spectacularly tangy and complex.
And kimchi can take hundreds of forms—from minty, sawtoothed perilla leaves slathered in a pungent paste to crunchy radish planks steeped in a clear, refreshing brine.
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The Enduring, Evolving Tradition of Kimjang
Long after Susan Park, a California-based Korean food historian and nonprofit director, and her family emigrated from Seoul to Los Angeles in 1975, her parents continued to do kimjang—not because they didn’t have access to kimchi (there was plenty available in nearby Koreatown) but because the ritual of making and sharing kimchi is as essential to Koreans as kimchi itself.
Throughout much of Korea’s history, harsh winters and food insecurity made the preservation of crops vital to survival.
Kimjang, which refers to both the act of making kimchi and the occasion itself, emerged as a communal event where families and neighbors would gather to collectively salt, season, and pack vegetables into onggi (earthenware vessels) before burying them in the ground to ferment. Over time, it also became a way to preserve one’s cultural heritage. In fact, in 2013, the United Nations Educational, Scientific and Cultural Organization (UNESCO) inscribed kimjang, or gimjang, on its list of Intangible Cultural Heritage traditions.
Now that most Koreans have year-round access to fresh produce, refrigeration, and commercial kimchi, Park said kimchi has shifted from a food necessity to a food preference and that the tradition of kimjang has adapted accordingly.
Many modern Korean households do kimjang on a small scale and have kimchi refrigerators that are calibrated for favorable fermentation conditions. Korean newscasters report annually on the kimjang index—the price of the raw materials for kimchi as well as the weather conditions as they relate to the harvest—and kimchi-making is woven into the elementary school curriculum.
“It’s still very much a part of Korean culture,” Park said. “There’s just no Korean food without kimjang.”
But according to Park, baechu kimchi, the kind made with napa cabbage, is “the iconic food of the Korean people.”
Most traditionally it features halved or quartered heads (known as tongbaechu or pogi kimchi), but plenty of cooks cut the leaves into bite-size pieces for mak (“easy”) kimchi. Either way, the cabbage gets salted, rinsed, and then smothered with brick-red gochugaru (Korean chili flakes); aromatics such as garlic, scallions, and ginger; and an umami-rich paste that transform the thick ribs and frilly chartreuse leaves into a wilted pickle that’s tangy, juicy, a little spicy, and fizzy with effervescence.
Once you make a batch (a simple, rewarding, fascinating project and a natural entry point into lacto-fermentation), you’ll feel its gravitational pull every time you open the fridge—not only because there’s nothing easier or more satiating than kimchi alongside a scoop of rice but also because kimchi is a culinary spark plug.
It’s the ruddy, sour core of Korean classics such as kimchi jjigae (kimchi stew) and kimchi bokkeumbap (fried rice) and can be a dark horse in anything from grilled cheese and burgers to creamy dips and grain bowls.
Here’s an in-depth look at how it works and my formula.
Salting
Method: Layer cabbage in bowl with salt and let sit for 2 hours, tossing periodically.
Explanation: Salt works hard on the cabbage. It draws out water so the kimchi isn’t too liquidy, removes sulfurous flavor, collapses some of the leaves’ cells so it’s easier for good bacteria to get in and do their job, softens the leaves’ structure so they shrink and pack tightly in a container, and slows the action of pectin-digesting enzymes that would otherwise make the cabbage mushy.
Meanwhile, it pulls water from bad microbes, diminishing their numbers so they can’t spoil the cabbage and clearing the way for beneficial microbes such as several species of lactic acid bacteria (LAB) to carry out the fermentation process by converting sugars into lactic acid. It’s important that the salt measure about 2 to 3 percent of the weight of the cabbage: enough to inhibit unwanted microbes but not so much as to make the kimchi too salty.
“By adding salt, we’re actually making a quite sophisticated selection of what microbes will grow,” said Arielle Johnson, flavor scientist and author of Flavorama: A Guide to Unlocking the Art and Science of Flavor (2024), when she lectured at Harvard University in 2022 about fermentation.
Recently when Johnson and I spoke about lactic acid fermentation (or lacto-fermentation), she noted that some species of bacteria can’t tolerate salt, while others, such as LAB, can (to a certain degree). That’s a good thing, because it allows you to more or less fix the game for the good bacteria by eliminating the bad kind.
Seasoning
Method: Microwave mixture of sweet rice flour and water until it thickens. Grind seasonings (including flour paste) in food processor. Coat cabbage with seasoning mixture, adding carrots, scallions, and ginger.
Explanation: The cocktail of seasonings flavors the cabbage and also feeds the LAB so they can vigorously multiply and ferment the vegetables. The faintly fruity heat of gochugaru is standard, as are pungent garlic and scallions and bright, peppery pops of ginger. Many cooks add a hint of sweetness with carrots, Asian pear or apple, and maybe plum syrup, the sugar of which doubles as food for the microbes.
And typically there’s at least one form of jeotgal (salted fermented seafood)—fish sauce, shrimp, oysters, belt fish—that pulls it all together with briny, umami-rich funk. Meanwhile, the pudding-like starch paste helps the seasonings cling to the cabbage and supplies more food for the microbes. I chose pear, fish sauce, and salted fermented shrimp, grinding them to a paste in the food processor before pulsing in the cooled flour paste and tossing the mixture with the cabbage, carrot matchsticks, scallions, and ginger.
The Seasoning Mix
Each component in the paste encourages lacto-fermentation and/or adds flavor and color.
- Sweet rice flour “pudding”: food for LAB; viscosity
- Asian pear: food for LAB; subtle sweetness
- Gochugaru: heat; sweet depth; color
- Fish sauce, salted fermented shrimp: food for LAB; briny umami; complex funk
- Garlic: savory bite and complexity
- Carrots: food for LAB; subtle sweetness; color
- Scallions: Grassy bite; color
- Ginger: pops of bright, zingy freshness
Primary Fermentation
Method: Pack seasoned cabbage into container and cover surface of cabbage with plastic wrap. Cover container and let sit at room temperature to ferment.
Explanation: The LAB thrive as the mixture sits, consuming sugars and producing lactic acid. As that acid builds, it lowers the mixture’s pH and makes it increasingly inhospitable to unwanted bacteria so that the kimchi can be stored indefinitely, and it gives the kimchi its craveable tang. The LAB also generate carbon dioxide, which forms bubbles in the juices that give the cabbage delightful effervescence.
Along the way, there’s more flavor development. The cacophony of constituent parts (garlic, ginger, etc.) that you taste on day one smooths out into a harmonious whole by day two or three. Meanwhile, other cell processes create complex savoriness and funk.
“You get what we call secondary metabolites,” Johnson said, noting the creation of organic acids and molecules, such as diacetyl and butyric acid, that carry buttery, cheesy aromas. “All of these extra little bits of stuff can create what we read as a cheesy flavor.”
Time and temperature are big factors. At room temperature (65 to 70 degrees) the mixture is tangy after two days but can be left up to five to build funk. Slightly cooler temperatures work, too; the reactions slow, so there’s even more flavor development. Just avoid anything warmer, which speeds lactic acid production while secondary flavors lag behind, resulting in kimchi that’s tangy but less complex.
Science: Every Batch Is Unique
Lactic acid bacteria are largely responsible for not only kimchi’s tang and funk but also the unique complexity from one batch to another. Those flavor gradations depend on the species of bacteria, the substrate, and the fermentation temperature, all of which work to produce secondary metabolite compounds that give each batch distinction.
Secondary Fermentation
Method: Refrigerate kimchi.
Explanation: As soon as the kimchi hits your sweet spot for tanginess (in the 65- to 68-degree test kitchen, we liked three days), move it to the fridge for long-term storage indefinitely. Kimchi does not go bad; it simply matures as fermentation chugs along at fridge-cold temperatures. As long as the vegetables are submerged in the brine and there is no visible fuzzy mold at the surface, it’s good to eat.
In fact, kimchi gets better with age. The flavor and textural changes it undergoes are profound and marvelous and give the ferment tremendous range and utility over the course of its life cycle. Eat it when it’s a week or two old if you like a brighter, crisper pickle, or leave it for months or even years if you prefer it softer, sparklier, and deeply pungent. Ideally, you enjoy it at every stage.
“It comforts me to have aged kimchi,” said Park, noting that she usually waits at least a month to start eating hers. “The kimchi I have in my refrigerator right now is about two and a half years old.”
The Life Cycle of Kimchi
Kimchi doesn’t go bad; as long as it’s properly stored (vegetables are submerged in liquid, container is refrigerated), it matures and arguably improves with age. The following are commonly recognized (but not industry-regulated) stages of fermentation; telling them apart is a matter of smelling or tasting them.
Geotjeori (fresh, unfermented)
- Profile: crunchy, sweet, salad-like
- Traditional uses: with rice, kalguksu (knife-cut noodle soup), juk (porridge), bossam (boiled pork belly), Korean barbecue, raw oysters
- Other suggested uses: with rich meats or seafood, cold noodles, or grain bowls
Kimchi (about 2 days–3 months)
- Profile: tangy, crisp-tender
- Traditional uses: banchan (small side dishes essential to every Korean meal); with rice
- Other suggested uses: condiment for tacos, hot dogs, burgers, or sandwiches; blended into creamy dips
Shin Kimchi (at least 3 months)
- Profile: sour, tender
- Traditional uses: kimchi jjigae (kimchi stew), kimchi bokkeumbap (kimchi fried rice), kimchi jeon (kimchi pancakes)
- Other suggested uses: braised and stir-fried dishes, tacos, burger topping
Mugeunji (at least a year)
- Profile: extremely tender, sour, deeply complex
- Traditional uses: kimchi jjigae, kimchi bokkeumbap, kimchi jeon, kimchi jjim (braised kimchi and pork)
- Other suggested uses: braises, stews, stir-fries
