FermenteaWhere food goes to change
← Equipment

Equipment · Industrial and laboratory plant

Industrial koji drum or aerated cultivation bed

Loading ratings…

Industrial koji machines cultivate mold on prepared grain before sake, shochu, miso or soy-sauce production. Commercial designs include rotating drums and aerated beds.

Suggest a correction
Two distinct industrial koji-making options: a horizontal enclosed drum and a separate shallow mesh aerated bed.

Koji is cultivated before the mash

An industrial koji drum or aerated bed is used for the aerobic mold-growing stage upstream of sake, shochu, miso or soy-sauce fermentation. The machine holds prepared material—often steamed rice or another cereal substrate—while koji mold grows through it. It is not the later liquid mash tank. The distinction matters: during solid-state cultivation the grains remain separate or in a shallow bed, and the system must deliver oxygen while managing the heat and moisture produced as the culture grows.

The 2021 review of Japanese miso and koji making explains that mechanical systems supply fresh air around or through the layer to limit heat build-up and exchange oxygen and carbon dioxide. It classifies interior-ventilation machines by loading arrangement: fixed beds, shelf beds, rotating drums and rotating discs. These names describe different engineering layouts; the word “koji machine” alone does not specify a vessel, airflow path or handling sequence.

Sources for this section

A drum and a bed are different systems

Fujiwara Techno-Art lists drum and rotary koji machines separately. One manufacturer-listed drum model integrates washing or soaking, steaming, cooling, inoculation, cultivation and discharge in the same container, and uses a board to keep the substrate layer more even. The company says automated tending and leveling are part of that machine’s workflow; sealed versions are available. Those features describe this product family, not a requirement for every koji maker. The visible Fujiwara example is a horizontal enclosed drum within a frame, with an access opening and service connections.

Nagata’s Visser machine is a bed-based alternative. Its published sequence puts inoculated steamed rice on a retractable bed, then onto a mesh shelf in the cultivation box. A fan circulates air through the koji layer and periodically reverses direction. Duct openings alternate exhaust and intake, helping remove humid air and cool the bed. Nagata describes the design as drawing on bed koji. Its image shows a broad shallow shelf chamber and ductwork rather than the horizontal rotating drum shown in the Fujiwara listing.

Sources for this section

Airflow and turning control the solid bed

The machine’s engineering problem is to keep a living, damp grain layer supplied with oxygen without letting respiratory heat accumulate or the surface dry excessively. A drum can rotate or turn its load; a fixed or shelf bed instead relies on air distribution and may use automated handling between surfaces. The exact balance depends on the model, substrate and koji process. The review describes surface and interior ventilation as different approaches and notes that fresh air can be temperature- and humidity-managed. The Visser design illustrates another option: reversing flow and alternating duct openings through the shelf layer.

Air movement is therefore not merely ventilation for the room. It is a way to remove heat and moisture from the material and make conditions more even across the layer. The sources do not establish a single airflow rate, temperature schedule or endpoint for all machines. A setting from one producer’s koji or equipment manual should not be presented as a universal operating specification.

Sources for this section

Material, scale and what the records do not establish

Nagata specifies stainless steel for easy cleaning on the Visser equipment. Fujiwara’s drum listing illustrates a different enclosed production system, but the sources do not give one material specification that applies to every manufacturer or every surface. Likewise, the capacities, dimensions, utility requirements and installation needs are model-specific; this record does not assign one standard size to a class that includes both drums and beds.

Fujiwara Techno-Art and Nagata Brewing Machinery are Japanese manufacturers with listed company addresses in Okayama and Kobe respectively. That establishes a Japanese commercial context for the examples, not a precise birthplace or a claim that the equipment is used only in Japan. The cited material documents contemporary machines but gives no date for their invention or first adoption. A producer choosing equipment would need the maker’s current model documentation for capacity, substrate compatibility, sanitation procedures, airflow controls and electrical specifications.

Sources for this section

Equipment details

CapacityNo general capacity is established for this class. Fujiwara lists a model-specific drum range in its product material; capacities cannot be transferred to other machines or bed systems.
SizeNo class-wide dimensions are stated in the cited sources; production systems are selected and configured by model.
PowerElectric Powered fans and automated turning/rotating mechanisms are described or shown. The cited sources do not provide voltage, power draw or connection specifications; electric drive is an inference from those mechanisms.
How you get oneNot established Manufacturers list these machines and invite inquiries, but the sources do not establish a general purchase, delivery or commissioning route.

Made of

  • Stainless steel — Structure and food-contact surfaces on the cited Visser bed system
    Nagata specifies stainless steel for its Visser machine; materials and contact surfaces vary by model and should not be generalized to every koji system.

Places

Japan

Manufacture · Country evidence

Fujiwara Techno-Art and Nagata Brewing Machinery list koji-making equipment and give Japanese company addresses. This row locates the cited makers; it does not claim every machine is made or used in Japan.

More equipment from JapanLocation source 1 → · Location source 2 → · Location source 3 →

Related

Used for

  • Rice koji

    Rice koji is steamed white rice through which koji mold has grown. It carries the enzymes that turn rice starch into sugar, and it is the starting point of sake, sweet miso, amazake and shio koji.

More from Japan

  • Adjustable yogurt-maker

    A small electric incubator holds jars at a selected temperature for yogurt and other documented warm food preparations. Controls, capacity and vessel arrangement vary by model.

  • Awabancha tub

    A large wooden tub used in Tokushima to ferment heated, worked Awabancha leaves with their cooking liquor. Its size and construction details are not specified in the sources.

  • Awamori kame

    A ceramic jar used in Okinawa to store and mature distilled awamori into kusu; it holds the finished spirit after distillation rather than fermenting the rice mash.

  • Coopered barrel, cask and large wooden vat

    Coopered vessels use shaped staves and hoops, but portable barrels, large foeders and upright wooden vats serve different roles. Materials and uses vary by place and process.

  • Food-contact cloth

    A cloth listed for steaming rice in a rice-koji method and identified as cloth for a koshiki in a brewery-museum caption; its fiber, weave, and size are not specified.

  • Goishicha weighted fermentation tub

    A Goishicha weighted tub holds tea leaves and steaming liquor during the second, wet fermentation stage in Ōtoyo, Kōchi. A current producer photograph documents one covered wooden tub under concrete-block weight.

  • Hatcho miso stone-weighted kioke

    A coopered wooden kioke used by Kakukyu in Okazaki for Hatcho miso: a broad vat capped with a carefully stacked pyramid of river stones during maturation lasting more than two years.

  • Katsuobushi smoking and drying equipment

    Enclosed cooking, smoking and drying equipment used in the multi-stage process that makes katsuobushi, the dried, smoked and mould-treated bonito of Japan, in repeated stages.

Community

No community contributions have been published for this entry yet.

Share what you made

Sign in to contribute. Published comments and photos are free to read.

Share a creation photoSuggest a correction

Sources