Meju (Korean: 메주) is a brick of dried fermented soybeans.[1] While not consumed on its own, it serves as the basis of several Korean condiments, such as doenjang (soybean paste), ganjang (soy sauce), and gochujang (chili paste).[1]Meju is produced by pounding, kneading, and shaping cooked soybeans, and undergoes fermentation with Aspergillus oryzae and/or Bacillus subtilis.[1][2]
Meju is usually made between October and December, typically around ipdong in early November.[17] However, the specific time and the process followed when making meju varies across regions, and depends on which food it will be used to make. Meju for Korean royal court cuisine was made around the fourth month of the lunar calendar, while meju made for home cooking was made around the tenth or twelfth month of the lunar calendar.[17] In Sunchang, meju for gochujang was made around August and September.[17] Traditionally, meju for ganjang and doenjang (which are produced together) are made entirely of fermented soybeans, while meju for gochujang are made using soybeans mixed with rice, barley, or wheat. If wheat is used, the ratio between soybeans and wheat is 6:4; if glutinous rice is used, the ratio between soybeans and glutinous rice is 5:2.[17]
Soybeans are washed, soaked overnight, and cooked.[17] They are usually boiled in a gamasot (cauldron), but can also be steamed in a siru (steamer), for at least three to four hours and usually five to eight hours.[17] Cooked beans are drained in a sokuri (bamboo basket) and pounded in a jeolgu (mortar) while still hot.[17] About 1.8–3.6 litres (0.40–0.79 imp gal; 0.48–0.95 US gal) of pounded soybeans are chunked, compressed, and shaped into a cube or a sphere to form meju.[17] The meju bricks are then dried in a cool shaded area until firm.[17] When the bricks harden, they are tied with rice straws to the eaves of the house for air-drying, during which the rice stalks transfer Bacillus subtilis bacteria to meju bricks.[17][18] Fungi and bacteria, mainly Bacillus subtilis and various Aspergillus strains, are responsible for the fermentation of meju.[2][19] Well fermented meju bricks are washed and sun-dried for later use.[17]