Korea.
Fresh kimchi is crisp and salty; ripe kimchi is tangy and fizzy; over-ripe kimchi is sour, soft — and perfect for stew. The fridge decides which you have.
The Korean table is rice (bap), soup or stew (guk, jjigae) and banchan (반찬), several small side dishes shared by everyone: kimchi, seasoned vegetables (namul), braised tofu, small fried fish. Its seasonings are the three jang, fermented over months from meju — blocks of cooked soybeans fermented by moulds and bacteria (XIV.7): ganjang (soy sauce), doenjang (soybean paste) and, with chilli powder and glutinous rice, gochujang. Sesame oil, garlic, scallion and gochugaru (Korean chilli flakes) complete the pantry. Bibimbap, bulgogi, jjigae and the many kimchi stews show how they combine.
Kimchi is lactic fermentation (XIV.3, XIV.4): napa cabbage salted to draw out water and season it, then rubbed with a paste of gochugaru, garlic, ginger, scallion, fish sauce or salted shrimp and often a little rice porridge, packed tightly so that lactic acid bacteria — Leuconostoc first, then Lactobacillus — sour it. Its ripeness follows acidity: about 0.6–0.8 % lactic acid and pH near 4.2 is the peak — tangy, crisp, lightly fizzy; above about 1 % it is over-ripe, sour and soft, best for cooking. Fermentation speeds up steeply with warmth, so kimchi is left a day or two at room temperature and then held cold; kimchi refrigerators keep it at about −1 to 0 °C for months. The workshop ripens kimchi.
Below: the acidity of kimchi over the days you choose at the storage temperature you choose (teaching model: logistic rise to about 1.4 % lactic acid, the time scale tripling for every 10 °C colder, calibrated to optimum ripeness in about two days at 20 °C), with the optimum band.
- Know the three jang and banchan.
- Make napa cabbage kimchi.
- Control ripening with temperature.
- Use over-ripe kimchi in cooking.
Warm to start, cold to keep
In the teaching model kimchi reaches its optimum after about 2 days at 20 °C, about 13 days in a fridge at 4 °C and about 22 days in a kimchi refrigerator at −1 °C — the reason Korean households can eat the November kimjang through the winter. Many cooks leave fresh kimchi out for a day to get the fermentation going, then refrigerate it; open jars release fizz and smell, so they are kept tightly packed and pressed down under the brine.
Napa cabbage kimchi: quarter 2 kg napa cabbage lengthwise, salt between the leaves with about 120 g coarse salt (and a little water), leave 6–8 hours turning once until the white ribs bend without snapping; rinse three times and drain well. Make a paste of 50 g gochugaru, 6 garlic cloves, 20 g ginger, 3 tbsp fish sauce, 1 tbsp salted shrimp, 1 tbsp sugar and a few spoons of cooled rice-flour porridge; add sliced scallion and julienned radish. Rub the paste between every leaf, pack the quarters tightly into a jar, press out air, leave at room temperature a day, then refrigerate. Over-ripe kimchi goes into kimchi jjigae with pork belly and tofu, or kimchi fried rice.
Keep two jars from one batch of kimchi, one at room temperature and one in the fridge. Taste both every two days.
Terms
- Jang (장)
- Fermented soy seasonings: ganjang, doenjang, gochujang.
- Banchan (반찬)
- Shared small side dishes.
- Kimjang
- The communal making of winter kimchi.
- Over-ripe kimchi
- Very sour kimchi, best for stews and fried rice.
Sources
- Korean kimchi science (e.g. K.-Y. Park et al., Journal of Medicinal Food 17 (2014) 6–20): kimchi is best at about 0.6–0.8 % titratable acidity (as lactic acid) and pH about 4.2; it ripens in a few days near 20 °C and over weeks near 0–4 °C. UNESCO inscribed kimjang, the communal making of winter kimchi, in 2013.
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.