Rice koji substitutes

The same mould grown on pearled barley or on soybeans instead of rice, sold dried in the same aisle of a Japanese grocer.

Best for

miso, amazake, shio koji, marinades, pickling beds

This is the only true substitute, because it brings the same working enzymes rather than an imitation of the flavour. Barley koji is earthier and slightly nuttier, and miso made with it comes out darker, drier-tasting and more rustic than the pale sweet miso rice koji gives. Amazake made with barley koji is less delicately sweet and a little grainy. Everything still works; the result simply tastes like a different regional style, which it is.

Rice koji already blended with salt and water and matured into a pourable seasoning. Stir it into marinades or dressings in place of the loose grains.

Best for

marinating fish, marinating chicken, dressings, quick pickles, seasoning vegetables

For any use where koji is seasoning food rather than fermenting it, this is the practical answer, and it still tenderises because the enzymes survive the salting. Two differences matter. It is salty, roughly 10 percent salt, so you must reduce salt elsewhere or the dish will be aggressive. And it is liquid, so it will not work anywhere the dry grains are structural, such as a miso mash or a nukadoko pickling bed.

Whisk shiro miso with a little sake or water until it is the consistency of double cream, then coat fish or chicken and rest it for a few hours.

Best for

marinating salmon, marinating cod, chicken, aubergine glaze, dressings

Miso is what koji eventually becomes, so it carries the right sweet-savoury amino-acid flavour and will give you a properly delicious marinated fish. What it will not do is the enzymatic work: most retail miso is pasteurised, so it seasons the surface instead of loosening the protein through the flesh, and the fish stays firmer rather than turning silky. It also browns much faster under a grill, so drop the heat and watch it. Not a substitute for making miso, obviously.

Sprouted barley ground to a powder, sold to bakers. Whisk into warm rice porridge held at about 140F for several hours to sweeten it.

Best for

sweetening rice porridge, amazake-style drinks, sweet rice puddings

Malt carries amylase, the enzyme that turns starch into sugar, so it will genuinely sweeten cooked rice the way koji does and you can make a rough amazake with it. What it lacks is protease, the enzyme that breaks protein into glutamate, and that is where koji's savoury depth comes from. So this works for sweetness and fails completely for miso, soy sauce or anything that needs umami built from protein. The result tastes maltier and cleaner, more like a barley drink than amazake.

The sweet, thick, non-alcoholic rice drink that koji is used to make, sold in cartons and pouches at Japanese groceries.

Best for

sweetening, smoothies, marinades, baking, salad dressings

If your reason for buying rice koji was to make amazake, buying amazake skips several hours of holding rice at a precise temperature and tastes essentially the same, because it is the same thing finished. It also works as a sugar substitute in dressings and marinades where you wanted koji's gentle sweetness. It cannot be used to start any other ferment, since commercial amazake is pasteurised and the enzymes are dead.

Fruit and ginger carry their own protein-cutting enzymes. Mix into a soy-and-sesame marinade and keep the contact time short.

Best for

tenderising beef, tenderising chicken, Korean-style marinades, quick marinades

This is the honest least-bad answer when the only reason a recipe reaches for koji is to make meat tender and juicy. Bromelain from pineapple and actinidin from pear and kiwi do break protein down, and quickly. Too quickly, in fact: leave meat in pineapple for two hours and the surface turns mushy and mealy, where koji works slowly and evenly overnight. You also get obvious fruit sweetness and no koji aroma at all, so the dish tastes sweeter and fruitier rather than deeply savoury.