Koji
Aspergillus oryzae · Fungus
Top 10 pairings
Koji is the fluffy white-and-gold mould Aspergillus oryzae grown deliberately on steamed grains — most often rice, but also barley and soybeans — to make the fermentation starter behind miso, soy sauce, sake, mirin and amazake. Named a "national fungus" of Japan, it is arguably the most important culinary mould on Earth: as it grows it floods its grain with enzymes that break starch into sweetness and protein into savoury, umami-rich amino acids, the biochemical engine of much of East Asian cuisine.
Picking a good onedrag
White-furred, sweet, grains looseBlotched, sticky, sour
Shop freshEveryday bestThe all-rounder: miso, shio koji, marinades, curing fish and meat.
The bloom on the grainWhite softening to a faint cream-yellow
The pack in the handFridge-cold, a light haze on the film
How it breaks upBreaks up easily, grains stay separate
Open it and smellSoftly sweet, like warm cooked rice
What you get from one
100%
Edible part
nothing to trim - grain and all
Keeping ittap a temperature
A domestic fridge holds it about 3× longer than the counter.
Sealed, as it was packed
Humidity
Airtight, air pressed out
Airflow