Suan cai (酸菜, suāncài, “sour vegetable”) is the name for soured vegetables across China, made from different greens in different
regions. In the Northeast (Dongbei: Heilongjiang, Jilin and Liaoning) it means napa cabbage (大白菜, dàbáicài) fermented in salted
water until it turns sour (Chinese Wikipedia). The cabbage, water and salt are the whole recipe; Dongbei suan cai is
made “without any added condiments” (Xu et al., 2024).
Pickled vegetables have a long written history in China. Classical texts call them zū (菹): a poem in the Book of Songs (Shijing)
describes melons “peeled and pickled” (是剝是菹) as an offering to the ancestors (Shijing, Xin Nan Shan), and the
farming manual Qimin Yaoshu has a chapter of 菹 recipes that includes salted cabbage (菘) (Qimin Yaoshu, chapter 88).
In Dongbei it’s a winter food. The Northeast was once too cold to grow leafy vegetables through the winter, so households pickled
the autumn cabbage (Yang et al., 2014), traditionally starting in early October (Wang et al., 2026).
Households differ in the details. Whole heads are aired for anything from two days to two weeks, and the wilted outer leaves are
trimmed off. Most accounts then blanch them in boiling water for 1–3 minutes, though one study of a traditional batch only washed
them. The heads are layered in a big earthenware crock (缸, gāng) with about 1% salt and covered with water (some families use the
water left from washing rice), usually under a heavy stone that keeps them pressed down and air out. The crock stays indoors in the
cold for a month or more: around 10°C in a recent review, and just above freezing in other accounts (Wang et al., 2026;
Yang et al., 2014; Chinese Wikipedia). That cold start works over a long northern winter, but it’s slow
and hard to judge, so for a home batch start it warmer (see below).
The same name covers different ferments elsewhere in China. The suan cai in Sichuan’s sour fish soup (酸菜鱼, suāncài yú) is made
from mustard greens, not napa cabbage, and so is the suan cai of Shanxi, northern Shaanxi and central and western Inner Mongolia,
where it is called huangcai (黄菜, huángcài) (Chinese Wikipedia). Sichuan’s everyday pickle in a reused, spiced brine
is pao cai. In Thailand and Vietnam, mustard greens make the closest relatives (Wikipedia), such
as Vietnamese dưa muối.
How Suan Cai Is Eaten
Suan cai is almost always cooked. To use it, a cook lifts out a head, rinses it to take off some of the sourness and slices it
very thin. The best-known dishes are suan cai with boiled pork belly (酸菜汆白肉, suāncài cuān báiròu), suan cai with blood sausage
(酸菜血肠, suāncài xuècháng) and suan cai stewed with frozen tofu (酸菜炖冻豆腐, suāncài dùn dòng dòufu). It also goes into stir-fries and
hot pot, and the tender centre of the head is eaten raw (see the FAQ on eating it raw). Pork is its usual partner; in pork dumplings, suan cai makes the usual
vinegar dip unnecessary (Chinese Wikipedia).
The line “Cui Hua, shang suancai!” (“Cui Hua, bring out the suan cai!”) comes from Xue Cun’s song “Dongbei ren dou shi huo Lei
Feng” (东北人都是活雷锋, “Northeasterners are all living Lei Fengs”). The song became a nationwide internet hit in 2001, and the line
became a catchphrase (Beijing News, 2018). Suan cai is also made commercially in Northeast China and sold mostly in the three northeastern
provinces (Wang et al., 2026).
What the Studies Say About Salt
Published descriptions don’t agree. One study describes traditional suan cai as cabbage in “a 0.5–3.5% salt solution”, left at
18–20°C for a month (Yang et al., 2020, household study). Another gives “2–6% salt”
(Cao et al., 2022), and a 2024 paper says 2–10% (Li et al., 2024). Traditional accounts start lower, at
about 1% of the cabbage (Wang et al., 2026; Yang et al., 2014).
Two studies compared levels directly. A team from Dalian fermented Northeast suan cai at 0.5, 1.5, 2.5 and 3.5% salt (w/w; the
abstract doesn’t say of what). At 2.5%, the lactic acid bacteria were significantly more numerous. The pH also fell fastest and the
most acid built up there, and the tasting panel scored it best (Yang et al., 2020). Another Dalian group preferred
6% salt for the flavour and Lactobacillus count in its own suan cai (Liang et al., 2020), so the studies don’t agree
on a single best level. This recipe uses 2.5%, the lower of the two tested favourites.
For halved heads in water, work the salt out on the cabbage and the water together, because the two even out over the first weeks.
Salt equal to 2.5% of their combined weight is at or above the Yang study’s 2.5%, whichever way that was measured, and inside the 2–6%
range other researchers give. Dissolved in the water alone it makes a brine of about 5%, which falls to about 2.5% as it evens out with
the cabbage. That is more than the traditional 1%, for a reason: in the Yang study the lower levels acidified more slowly, and in a home
kitchen, warmer than a 10°C winter crock, a slow acid start gives spoilage microbes and nitrite more time. Don’t cut it: NCHFP lists a brine
that is too weak as a cause of soft, slippery pickles (NCHFP). It’s the same arithmetic as for Balkan
kiseli kupus, the closest European relative, and our salt and brine calculator does it for
other vegetables.
Nitrite: the Reason to Wait Four Weeks
Napa cabbage carries nitrate. In the first days of fermentation, bacteria turn some of it into nitrite; as lactic acid builds up,
the nitrite is broken down again. Every suan cai study we found that tracked nitrite shows this rise and fall
(Wu et al., 2015), and three put numbers on it:
- In a lab batch of blanched napa cabbage in 2% brine at 10°C, nitrite in the brine went from 0.55 mg/kg to a peak of 32.15 mg/kg
on day 7, above China’s limit of 20 mg/kg, while the pH had fallen only from 6.8 to 4.7. By day 14 it was down to about 0.06 mg/kg,
with the pH near 3.6 (Xu et al., 2024). - In suan cai from three households in Dalian, nitrite peaked on day 3, at up to 29.50 mg/kg, then fell below 20 mg/kg and ended the
month at 0.58–0.73 mg/kg. One household’s batch reached pH 3.30 by day 7; the other two took until day 23
(Yang et al., 2020, household study). - A Dalian Medical University study of the bacteria and nitrite concluded that Northeast suan cai “should not be eaten until 4 weeks
of fermentation” (Zhou et al., 2018).
The household figures show why the calendar matters more than a sniff test: two of the three batches took 23 days to reach pH 3.3.
Wait at least four weeks. Eat it only when the leaves are sour and translucent right to the centre, and rinse it before cooking, as
Dongbei cooks do. Salted, pickled vegetables are also linked with stomach cancer in observational studies from East Asia, which is one
more reason to treat suan cai as a side or a stew ingredient; our dưa muối page sets out that evidence.
Cold Crock, Slow Ferment
The studies cover a range of temperatures: 10°C in the nitrite study, 15°C for 30 days in a study of halved cabbages with 6% salt
(Cao et al., 2022), and 18–20°C in traditional household practice as researchers describe it. NCHFP warns that
shredded sauerkraut may not ferment below 60°F (about 16°C) (NCHFP), but the 10°C suan cai study reached pH 3.6
in two weeks, so the cabbage in brine does sour in the cool (slowly: at 10°C it took two weeks just to pass the nitrite peak).
For a home batch, aim for 18–20°C (64–68°F), the temperature researchers give for traditional household suan cai. In a cooler room,
down to 15°C (59°F), expect it to take 5–6 weeks: NCHFP gives that long for sauerkraut at 60–65°F (16–18°C) and warns that below 60°F
it may not ferment (NCHFP). Either way, the batch is ready when it’s sour and translucent to the centre, not on a
fixed date.
The microbes come from the cabbage itself: Lactobacillus and Leuconostoc are among the main bacteria (Zhou et al., 2018),
with Weissella abundant in household batches (Yang et al., 2020, household study). Wu’s study also found yeasts and
a Penicillium mould (Wu et al., 2015), which is why the cabbage has to stay pressed under the water. A flat white film on
the surface (kahm yeast) can be skimmed; fuzzy or coloured mould, sliminess or a rotten smell means the batch goes. Our guide to
telling kahm yeast from mould shows the difference. If you’d rather shred and dry-salt your cabbage, that’s
a classic shredded sauerkraut.