What is shio koji?
Shio koji (also known as koji salt) is a Japanese condiment used for seasoning or marinating. It is a white, lumpy paste (think very loose rice pudding) with a mild, sweet miso-like flavour. It is available to buy from specialist stores or websites but easy to make at home, using only three ingredients; koji, salt and water. Koji is the bacteria starter used to make many Japanese fermented products such as sake, soy sauce and miso. It is an ancient ingredient but due to growing interest in fermented foods and their health benefits, it has recently increased in popularity as it is a tasty, slightly healthier alternative to salt.
To make it at home you will need koji rice – rice grains that have been inoculated with koji bacteria (or to give it its proper name, Aspergillus Oryzae). These also need to be sourced from a specialist supplier (there are many online), but as it is a dried product it will last indefinitely in your cupboard, whereas shio koji has a shorter shelf life. Read on for instructions on how to make your own shio koji.
How to make shio koji at home
Metric
Imperial
- 300g of dried koji rice
- 90g of fine sea salt
- 450g of mineral water
- Clean jay cloth
- Elastic band or kitchen string
- Kilner jar
Mix the dried koji rice with the salt and water
- 300g of dried koji rice
- 90g of fine sea salt
- 450g of mineral water
Place the mixture into a clean, sterilised jar and cover with a clean j-cloth and elastic band – this will allow the gasses created during the fermentation process to escape without the need to open the jar each day (and stop any unwanted wild yeasts or bacteria getting in)
Leave the jar to ferment at room temperature out of direct sunlight for 5-7 days (it will be quicker in summer or hot weather), giving the mixture a stir every day with a clean spoon. Top the mixture up with a little more mineral water if it’s looking dry. Start tasting the shio koji after day 4; once you’re happy with the flavour profile, place it in the fridge to halt the fermentation process. It is now ready to use
As it is a fermented product, the shio koji will happily sit in the fridge for months
How to use shio koji
Due to its fermenting qualities, shio koji makes an excellent marinade. It breaks down the enzymes in meat helping to tenderise it – try marinating chicken in it for a day for fried chicken or on tougher cuts of steak or pork for a softer flavour. When used to marinate fish, it helps draw out the moisture and firm up the flesh, making it excellent for pan-frying without the risk of it flaking apart, as well as seasoning the flesh all the way through. Check out the recipes below for great examples of using koji as a marinade.
You can make quick shio-koji pickles by marinating vegetables in it overnight – cucumber or daikon work well. After 24 hours, simply wipe away the marinade and eat straight away. For a Japanese take on the British classic of a pickled egg, try burying hard-boiled eggs in shio koji for up to a week
Using koji as a seasoning
If you aren’t keen on the lumpy texture, you can blitz shio koji into a smooth paste using a blender, then stir it through sauces or soups as a healthier, more complex seasoning than salt. Rosana McPhee flavours her Japanese cream stew with it for an extra umami hit.
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