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Why log-grown

Most shiitake in the world is grown on sawdust blocks. TAKEHISA buys the other kind.

Modern shiitake production is dominated by substrate cultivation, which is easier to manage and yields more. TAKEHISA has worked since its founding with log-grown shiitake: spawn driven into felled kunugi oak and left to the weather. It takes about two years instead of a few months, the labor is heavy, and the number of growers is falling, which is steadily making it a scarcer ingredient.

Origin and grade

Oita and Kumamoto produce the highest-regarded dried shiitake in Japan, and bidding rights at their auctions are hard to obtain. TAKEHISA holds bidding rights in both through long-standing relationships, which is what keeps the quality it buys consistent year to year.

  • Log-grown shiitake is scarce and getting scarcer
  • Oita is the most sought-after origin in Japan
  • Kunugi oak regenerates itself, so the cultivation cycle sustains the woodland rather than clearing it

How log-grown dried shiitake is made

Spawn goes into the log in winter. The first harvest comes about two years later.

Year one

  1. FellingFrom NovemberKunugi oak is felled with its leaves still on and left lying in the woodland so the moisture draws out through them.
    Felled kunugi oak logs stacked in the woodland, their sawn ends still pale
  2. Cutting and inoculationJanuary to MarchLogs that stored their nutrients before winter are cut to about one meter and driven with shiitake spawn dowels.
    Close-up of a cut kunugi log driven with shiitake spawn dowels, stacked in the shade with others
  3. Laying downThrough to the following autumnInoculated logs are stacked somewhere shaded and thermally stable so the mycelium can run all the way through.

Year two

  1. Raising yardFrom OctoberThe logs move to a raising yard, usually a cedar grove, where conditions suit fruiting.
    Shiitake fruiting from the bark of a kunugi oak log standing in a shaded raising yard
  2. HarvestMarch and NovemberThe March crop is called haruko and the November crop akiko.
  3. DryingAbout 20 hoursHarvested mushrooms go into a drier at 40 to 60 degrees Celsius (104 to 140°F) for roughly twenty hours. Growers do this themselves before shipping.
  4. AuctionDried lots are consigned to the agricultural cooperative and bought at auction. This is where TAKEHISA's selection starts.
    Boxed lots of dried shiitake laid out in long rows in the cooperative's auction hall

Where the umami comes from

Guanylate, and why drying is what creates it.

Guanylate is one of the three major umami compounds, alongside inosinate from bonito and dried sardine and glutamate from kelp and cheese. Dried shiitake is the richest common food source of guanylate, and combining it with a glutamate source multiplies the perceived umami rather than adding to it.

Drying is not preservation, it is a reaction

  1. In a fresh shiitake the ribonucleic acid and the enzyme that acts on it sit in different compartments, separated by cell walls, so no guanylate forms.
  2. Drying breaks those cell membranes down.
  3. Rehydrating extracts both the ribonucleic acid and the enzyme into the same water.
  4. Heating brings them together and guanylate forms, which is the deep savory character.

Rehydrate cold

  1. Above about 5 degrees Celsius(41°F) a nucleotide-degrading enzyme becomes active and breaks down the umami compounds you are trying to extract.
  2. Soaking in cold water in a refrigerator suppresses it.
  3. Warm-water soaking is faster and gives up most of the flavor.

Heat fast, then drop the heat

  1. Between about 45 and 60 degrees Celsius(113 to 140°F) the degrading enzyme converts guanylate into tasteless guanosine.
  2. Above 80 degrees Celsius(176°F) it is deactivated.
  3. So bring the pot up hard and fast to get through that band, then reduce to a medium or low simmer and let the flavor build.

Composition

Shiitake is low in calories and carries vitamins, minerals, and dietary fiber. Drying increases the dietary fiber, vitamin, and mineral content by a wide margin, and raises vitamin D in particular. The flavor is not limited to Japanese cooking: the concentrated savory character carries into soups, risotto, sauces, and plant-forward menus across cuisines.

How to rehydrate

Cold water, in the refrigerator, and time.

  1. Rinse brieflyRinse under running water just long enough to take off the surface dust, then move the mushrooms to a sealable container or bag. Allow room, because they swell.
  2. Cover with cold water and refrigerateFill with cold water at about 5 degrees Celsius (41°F), press the air out, and refrigerate. In an open bowl, hold the mushrooms under with a plate or a drop lid. Plain water is fine. In winter room temperature will do; in summer always refrigerate.
  3. Give it timeKoushin takes about five hours and donko about ten.Sliced product rehydrates far faster, which is often the reason to buy it.
  4. Keep the soaking liquidThe soaking water is a concentrated, aromatic dashi. Use it in miso soup, in simmered dishes, or in a stir-fry. Added to bonito dashi or chicken stock it lifts both.
  • Cold water and a slow refrigerated soak build the most flavor
  • The soaking liquid is dashi, not waste
  • Leftover rehydrated caps shred and freeze well, and the liquid freezes in cubes

Choosing and storing

What to look for

Umami content turns out to be roughly the same across grades. What a higher grade buys is aroma, appearance, thickness, and bite, which together make up the eating quality.

  • Cap top: glossy, not darkened
  • Cap underside: gills clean and pale yellow, with the cap not over-opened

Storage

Dried shiitake picks up moisture from the air. Move it into a sealed container with the desiccant that came in the bag, and keep it out of direct sunlight somewhere with air movement. Sealed and refrigerated it keeps for a long time, but the printed shelf life on the bag is what to work to.

If a stored batch does go soft, spread it gills-up on a rack on a clear day and leave it in direct sunlight for about two hours. It dries out again, and the ultraviolet exposure raises the vitamin D.

A long record

Accounts differ, but the outline is well documented.

800s, Heian period
The practice of drying shiitake reaches Japan from China, carried back by monks who had studied in Tang China.
1200s, Kamakura period
Most dried shiitake went to China. Dogen's Tenzo Kyokun, written after his voyage to Song China to study Buddhist law, describes an elderly temple cook coming out to a Japanese ship at the port of Ningbo to buy shiitake, and describes the mushrooms being dried.
1400s, Muromachi period
Presented as a luxury to figures including Ashikaga Yoshimasa, Toyotomi Hideyoshi, and Tokugawa Ieyasu.
1600s, early Edo
Cultivation begins to replace foraging: felled logs are scored with an axe and left in the forest.
1800s, late Edo
The commercial system takes its modern shape, with sorting and grade names set by cap size and form.
1900s, Meiji
Drying moves from sun-drying to charcoal and wood-fired drying and then to purpose-built driers, and quality improves sharply.
Showa era
Kisaku Mori's 1942 invention of the spawn dowel makes reliable cultivation possible and volumes rise. Dried shiitake changes from a luxury eaten on special occasions into an everyday household ingredient.

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