Deep Dive: Douchi (Fermented Soybeans)
One of the oldest Chinese ferments still working its magic
Hi! This is an ongoing series where I explore Chinese pantry staples, from black vinegar and Shaoxing wine to fermented tofu. You can find the full list here.
It’s wild to think that douchi, one of China’s oldest fermented foods, has been flavoring Chinese tables for more than 2,000 years.
Dòuchǐ (豆豉) is often translated as fermented black beans, which is only partly accurate. The most well-known varieties are dark brown or black. However, it’s made from yellow or black soybeans, not black turtle beans. Unassuming as they look, these little beans pack deep savory flavor and umami, making them a true workhorse of the Chinese kitchen.
While strolling through markets in southwestern China, from Guizhou to Yunnan during my recent trip in China, I discovered that douchi comes in far more forms than I had imagined. Piled high in baskets and tubs were beans in shades of beige, red, orange, and brown. The sheer diversity challenged my own understanding of the ingredient and the English translation of “fermented black beans.”
Even if you’ve never cooked with douchi, chances are you’ve tasted it in mapo tofu, steamed pork ribs at a Cantonese dim sum restaurant, or the black bean sauce from takeout dishes.
Long before I learned how to cook, I fell in love with its savory depth through Lao Gan Ma’s chili oil with fermented soybeans, spooned over canteen meals at my boarding school some 20 years ago1. It also builds the flavors of some of my favorite Sichuan dishes, from bubbling hot pot to salt-fried pork.
History and Production of Douchi
Douchi's history stretches back more than two millennia. It appeared as early as the Spring and Autumn and Warring States periods (roughly 700–200 BCE), and by the Western Han Dynasty, it was already a widely consumed food2. The lexicon Shiming defines it as “harmonizing the five flavors,”3 a testament to its importance in the ancient Chinese pantry.
At the time, the most common form was unsalted douchi, known as mild douchi (dan douchi, 淡豆豉). Douchi and salt formed a seasoning pair known as yan chi (盐豉). Before soy sauce, oyster sauce, and many of the condiments that define Chinese cooking today, salt and douchi were among the most essential flavorings.
Detailed production methods were later recorded in the Northern Wei agricultural text Qimin Yaoshu (Essential Techniques for the Welfare of the People). The book outlines several large-scale methods for making douchi and features both the fermented beans and their liquid in around 80 recipes, from marinades and soups to steamed dishes. Over the centuries, production techniques evolved, and regional variations emerged with the addition of different spices and seasonings.
The basic process hasn’t changed much over the centuries. Dried soybeans are soaked and cooked, then kept in a warm, dark place to allow mold (typically Aspergillus or Mucor) to inoculate the beans, either naturally or with a starter culture.
From there, the process varies by style. Cantonese Yangjiang douchi, for example, undergoes washing and a second fermentation. The beans are then mixed with salt and water, fermented for several months, and finally sun-dried.
Types of Douchi
A traditional saying goes: “Northerners love jiang, southerners love chi”4. It reflects a divide between northern cuisines, which tend to favor sauces and pastes, and southern cuisines, where douchi plays a larger role.
Today, the most famous regional varieties are from Guangdong, Sichuan, Hunan, and Jiangxi. There are a few different ways to divide douchi, such as the material, mold type, and flavor. Unseasoned douchi is rare now, mostly reserved for medicinal use.
Here I’m breaking them down into dry and wet douchi and comparing the four products made in Guangdong, Sichuan, Hunan, and Guizhou. This is by no means an exhaustive list. You will find douchi in Jiangxi, Shandong province, and unique compressed discs made by the Hani ethnicity in Yunnan5.
Dry douchi
Cantonese Douchi丨广东豆豉
The most famous and accessible version outside of China comes from Yangjiang (阳江), Guangdong. Made from small black soybeans inoculated with Aspergillus oryzae, it is fermented twice and sun-dried. The final product is small and relatively dry.
The famous black bean sauce, known as chizhi (豉汁), is typically made with chopped Yangjiang douchi, garlic, soy sauce, and sometimes dried tangerine peel, Shaoxing wine, and oyster sauce. It is indispensable in classic dim sum dishes such as steamed pork ribs (豉汁排骨) and chicken feet (豉汁凤爪). Douchi also features prominently in dishes like douchi chicken (豆豉鸡), stir-fried beef with peppers (豉椒牛肉), and seafood preparations such as stir-fried clams (豉汁炒花甲) and steamed fish.
Sichuan Douchi 丨四川豆豉
Sichuan varieties, most famously Tongchuan douchi (潼川豆豉) and Yongchuan douchi (永川豆豉) from Chongqing, rely on Mucor molds (the same used for fermented bean curd). Compared to the Cantonese douchi, these beans are larger, softer, and glossier because they skip the final sun-drying step.
These are essential in Sichuan classics like mapo tofu (mapo doufu, 麻婆豆腐), salt-fried pork (yan jianrou, 盐煎肉), twice-cooked pork (hui guo rou, 回锅肉), cold dressed rabbit (ban tuding, 拌兔丁), and steamed pork belly over fermented mustard greens (xian shaobai, 咸烧白). They also form the flavor for hot pot and dry pot bases.
Hunan Douchi丨湖南豆豉
Hunan is another region with a deep affinity for douchi, and a long tradition of producing it. Some have even been found at an archaeological site from 2000 years ago.
The best comes from the city of Liuyang (浏阳), using local small black soybeans. The beans are first steamed, then soaked and steamed again before being inoculated with Aspergillus oryzae. The finished douchi is dry and mild compared to the Sichuan and Guangdong varieties.
Douchi are used in a lot of steamed and stir-fried dishes, some similar to how it’s used in Sichuan and Cantonese cuisines. For example, dishes like home-style braised doufu (家乡豆腐, jiaxiang doufu), Hunan’s version of home-style tofu, steamed cured meats (腊味合蒸), and mostly famously, Hunan’s quick stir-fries with green pepper, lajiao chaorou (辣椒炒肉), also known as small-fried pork (小炒肉, xiao chaorou).
To compare the three dry douchi I have:
Flavor Intensity: Sichuan > Guangdong > Hunan
Texture (Wet to Dry): Sichuan > Guangdong > Hunan
Size (Large to Small): Sichuan > Hunan > Guangdong
Wet and Water douchi丨湿豆豉&水豆豉
Wet and water douchi are far less known outside China. Unlike the more familiar dry varieties, this style traditionally relies on wild bacteria (Bacillus subtilis) rather than mold, although some also use a Mucor starter culture.
Cooked soybeans are wrapped in dried grass or leaves and left to ferment until they become sticky, producing wet douchi (shi douchi, 湿豆豉), a close relative of Japanese natto. When the fermented beans are seasoned with spices and mixed with liquid, they become water douchi (shui douchi, 水豆豉).
This style is common across southwestern China, particularly in Guizhou and Yunnan where it is made at home or sold fresh at markets. (Both provinces also produce the more familiar dry black douchi.) In Guizhou, water douchi is commonly served as a side dish or incorporated into dipping sauces alongside scorched chili flakes, fish mint, and wild litsea pepper oil (木姜子油).
It is difficult to find outside its home regions, though Lao Gan Ma does carry a commercial version. It’s slightly funky in smell, spiced with chili and ginger, less salty than the dry varieties, and can be eaten as a rice side dish or dipping sauce.
Choosing and Storing Douchi
If you are new to the ingredient, Cantonese Yangjiang douchi is the best all-purpose entry point. It is often labeled as “preserved / fermented black beans” or “dried black beans”. Before I could source regional varieties here in Germany, I happily swapped Yangjiang douchi into Sichuan and Hunan recipes without issue. As you venture deeper into the world of douchi, however, you may find yourself seeking out regional styles, perhaps Sichuan douchi for a truly good plate of mapo tofu.
When shopping for dry douchi, look for beans that are firm, plump, and free from unwanted white mold. Once opened, I prefer to store them in an airtight container in the refrigerator. They keep for a long time, though well past their best-before date, they may develop a slightly sour or bitter taste.
Bonus: Douchi in other forms
While navigating the Asian grocery store, you will likely encounter douchi pre-processed into other pantry shortcuts:
Chili oil with fermented soybeans (风味豆豉辣椒): Lao Gan Ma’s version remains a personal favorite, and frankly, it is vastly underrated compared to their popular chili crisp. It is excellent over plain rice or tossed with noodles.
Douchi Dace (豆豉鲮鱼): This classic Cantonese canned fish pairs fried dace with savory fermented soybeans. It makes a quick meal over steamed rice, can be stir-fried with youmai cai (油麦菜, also known as a-choy or celtuce leaves), or used anywhere you might otherwise enjoy tinned fish.
Cooking with Douchi
Douchi is eaten as a side dish in many regions, although I find it more versatile in cooking. It appears in steamed, stir-fried, and braised dishes, pairing beautifully with pork, beef, chicken, seafood, tofu, and vegetables.
Before cooking, some suggest to briefly rinse the beans for a cleaner, less intense flavor (I normally skip rinsing). Depending on the dish, you may also want to roughly chop them so they disperse more evenly through a sauce, as in mapo tofu. In many recipes, however, the beans are left whole.
Blooming douchi in oil helps unlock its full aroma. Add it to medium-hot oil at the beginning of a recipe and fry until fragrant before adding the remaining ingredients. For steamed dishes, briefly warm the douchi with minced garlic in oil before mixing it with meat or fish. Some professional chefs even deep-fry douchi for up to 20 minutes, creating a crisp exterior while keeping the beans intact.
If you’re cooking with douchi for the first time, start simple: add a small spoonful to fried rice or stir-fried vegetables. A little goes a long way, and most recipes call for only 1 to 2 tablespoons.
Flavor Pairings
Douchi + garlic
Perhaps the most classic pairing of all. You’ll find it in countless stir-fries, braises, steamed dishes, and sauces.
Douchi + soy sauce, doubanjiang, and tianmianjiang
Douchi works particularly well alongside other fermented sauces
Douchi + chili peppers
In Cantonese cooking, it often appears with fresh bell peppers in stir-fries and steamed dishes known as chi jiao (豉椒). In Hunan, it is frequently paired with dried chilies. Whether fresh or dried, a little heat brings out douchi’s savory character.
Recipes
Mapo Tofu (updated recipe and visuals!)
At my boarding school canteen, we were allowed to bring our own chili oil to season our rice. As a result, I sampled nearly every variety of Lao Gan Ma at a young age, but the chili oil with fermented soybeans was always a classic
Qiu Pangtong, The History of Chinese Cuisine (邱庞同《中国菜肴史》).
Original text from Shiming: “豆，嗜也。五味调和，须之而成，乃可甘嗜也。” (《释名》).
Several traditional sayings reflect the historical divide between douchi-loving southern China and sauce-loving northern China, including “南人嗜豉，北人嗜酱” and “北人不可一日无酱，南人不可一日无豉.” Their precise origins, however, remain unclear.
Yunnan alone is home to numerous regional styles of douchi, including those from Dehong (德宏豆豉), the Hani communities (哈尼豆豉), Mile (弥勒风吹豆豉), and Yimen’s green soybean douchi (易门青豆豉).
Lao Gan Ma’s Douchi is my most favourite type of kind of Douchi, I have it with almost every meal I eat, as soon as I land in China I go to a supermarket or convenient store to get myself one or three bottles and before I leave I buy at least 5-10 bottles so I can have when I get back home to South Africa.
Thank you for sharing this article, it was such a delicious read.
Very insightful!!
Is douchi ever used in zhajiangmian, or is that really a different family of fermented bean products altogether?
I’ve mostly associated zhajiangmian with sweet bean sauce, but I’m curious whether there are regional versions that incorporate douchi as well.