Shio Koji Basics
Shio Koji is a great place to start understanding how you can use the enzymes produced by koji in your kitchen. It’s a simple ferment of koji, water, and salt.
Note: When fermenting anything, starting with clean, appropriate vessels and equipment is important. Glass or ceramic is great for this kind of fermentation project. Food grade plastic is OK, but metal vessels are not recommended.
How to make it:
If using dried koji, rehydrate your koji first (see “Using Dried Koji”).
Mix koji and and water in a 1:1 ratio, by mass.
Add salt to the mixture. Add between 6% and 10% by weight. Don’t include the weight of the salt in the calculation.
The salt concentration is a matter of preference, even 6% salt is plenty to inhibit unwanted microbes, and allow salt tolerant lactic acid bacteria to thrive. Higher salt content mixtures will last longer, as they are more hostile to other bacteria or yeasts, but might also take longer to ferment.
Fermentation can be done at room temperature or in the fridge. A sterilized glass vessel like a large jar is perfect.
At room temperature, cover with a clean cloth and stir daily. It should be ready within a week. Room temperature ferments can produce rich, funky flavours.
In the fridge, stir once or twice a week. Fermentation can take 3-4 weeks. This temperature range will inhibit many microorganisms, so the product will have a cleaner flavour.
Once it is completed, it can be sealed and stored in the fridge for many months. Mold will not regrow in the liquid, but try to keep the sides of the storage vessel clean after you take some shio koji out. If you allow residue to sit on the sides of a vessel outside of the liquid, it can attract unwanted microbes and spoil your shio koji.
Example Recipe :
Rehydrate 500 g of dried koji with 200 ml of warm water to produce 700 g of koji.
Combine with 700 ml of water.
Add 140 g salt (10% of the the combined weight of water and koji).
Mix well and ferment as described above.
How to use it:
In general, you will need little or no added salt when using shio koji in food, because it contains salt. The added umami also enhances the perception of salt on the palate. Shio koji can be left on or scraped off food before cooking, depending on the desired result.
Shio koji is an incredible ingredient, and a little will go a long way. Here are some ways you can use it:
Quick pickles. Prepare vegetables into bite sized pieces, then lightly coat in shio koji and refrigerate. Vegetables like cucumber and radish only need a couple of hours. More firm vegetables like cabbage or carrot will benefit from a day marinating. Add a splash of hon mirin to the marinade, if you like.
Marinade for protein. Will tenderize meat and produce fantastic browning and a rich fond in very little time. Thin slices are better than thick, if you are heating directly in a pan or bbq, as the rapid development of crust can lead to burning if you are not used to it. With thick slices, best to sear then finish in the oven. Also very good on tofu or other vegetable protein options.
Large cuts, such as a rack of lamb or beef prime rib can be coated in shio koji and marinated for 6 - 24 hours in the fridge. Scrape off the coating before roasting. Short term application will enhance the umami and browning, medium to long term can bring out more complex savoury flavours that you normally only see after dry aging. To accelerate the action of the shio koji, try coating the meat then cooking via sous vide,
Lightly coat vegetables like broccolini in shio koji, then saute with a little butter for a very satisfying dish. Add some shio koji to cut vegetables when tossing with oil, before oven roasting. Leave the prepared vegetables at room temperature for a little while before cooking. The more time you give the enzymes to work, the more effect you will see. Works very well with brassica vegetables.
Soups and stews can benefit from a savoury hit of shio koji to add depth of flavour.