Ishizuchi Kurocha (石鎚黒茶) is a post-fermented Japanese tea. The first part of the name references Mount Ishizuchi in Ehime and kurocha means black-colored tea, not to be mistaken for kocha which is black tea. Post-fermented or dark teas are called ato-hakkou (後発酵).
Ishizuchi Kurocha has been produced for centuries. Locals rarely drank it, except during seasonal events and when served to visitors. The tea was sold in bulk to shippers from Setouchi for use as a beverage, as an ingredient in porridge, and as a dye for fishing nets and other textiles In the 1950s, chemical dyes became popular and demand for the tea decreased significantly.
Until recently, the only person in Japan who knew how to produce Ishizuchi Kurocha was Mr. Masaki Sogabe. Mr. Sogabe retired several years ago around the age of 90. Concerned that the process might be lost, Satsuki-kai (さつき会), a life research group based in Saijo, learned the process and began producing Tengu Kurocha (天狗黒茶) which takes its name from Tengu peak on Mount Ishizuchi.
Ishizuchi Kurocha is produced in Komatsu, now part of Saijo in Ehime Prefecture. Attempts are currently being made to produce Kurocha in Hinohara village near Tokyo, with the approval of Mr. Sogabe.
Ishizuchi Kurocha is produced in very small quantities. In mid-summer, tea plant branches are cut, washed, and then steamed. During the steaming, the leaves will fall from the branches and be gathered for a two-step fermentation process. For the first stage, the leaves are stored in wooden boxes for four to five days during which it will develop aerobic fungi. For the second stage, the leaves will be removed and hand-rolled before being stored in plastic bags to ferment for two to three weeks during which Lactobacillales (lactic bacteria acid) will develop. Finally, the tea leaves are dried in the sun for two to three days. The fermentation process also produces organic amino acids like GABA.
Add 3 grams of tea leaves to 12 ounces of boiling water and simmer for 1 to 2 minutes before serving. Ishizuchi Kurocha may also be served cold.