KOJI RICE: WHAT IS SHIO KOJI (2025)

Shio-koji is a traditional Japanese condiment that is made from fermenting rice koji (mold-inoculated rice), salt, and water.

It is a versatile and natural flavor enhancer with a mildly sweet, salty, and umami-rich taste.

Recently shio-koji became popular for its health benefits and property to tenderize and enhance the flavor of foods.

WHAT IS KOJI RICE

Koji rice, known as “kome koji” (米麹), is steamed rice that has been inoculated with koji mold spores and allowed to ferment. It is deeply rooted in Japanese cuisine, playing a vital role in the production of traditional condiments such as miso, soy sauce, and mirin.

The koji mold, called koji-kin (麹菌) in Japanese, is scientifically known as Aspergillus oryzae. This beneficial mold has been officially recognized as Japan’s national microorganism due to its significance in fermentation.

If the idea of mold makes you wonder, “Is that safe to eat?”—rest assured! Aspergillus oryzae is a beneficial mold, much like those used in making cheese, sake, and other fermented foods.

One well-known product of koji fermentation is Shio Koji, a salt-based condiment made from koji rice. In 2011, Japan experienced a ‘Shio Koji boom,’ leading to a surge in its popularity and countless recipes incorporating this versatile ingredient.

You can consider getting koji rice from several sources, including specialty stores and online retailers. Japanese or Korean grocery stores often stock koji rice. Sometimes it is labeled as “koji mold rice (米麹/米こうじ)” or simply “koji (麹/こうじ).”

I personally purchase rice koji from Amazon which is the easiest way for me and for surely everybody.

Typically, koji rice is sold as a dried product.

• Premium Dry Rice Koji 3 Pack 900 grams use as koji starter or umami enhancer

WHAT IS SHIO KOJI

Today’s topic, “Shio-Koji” (塩麹)in Japanese, which means Salted Koji Rice.

Shio-koji is a thick paste/sauce-like condiment with a salty taste and funky sweet aroma like amazake.

The reason why Japanese cooking enthusiasts are obsessed with shio-koji is that it tenderizes the ingredients and at the same time brings out the natural flavor of the ingredients.

Koji contains many enzymes such as Proteolytic enzyme (protease) and starch-degrading enzyme (amylase).

• Protease→ decomposes protein into amino acids →Umami, a source of savory flavor.
• Amylase→ Decompose starch into glucose →Sweet
• Lipase→breaks down fat into fatty acids and glycerin →Cutting off the greasy taste

By the action of these enzymes, the meat is tenderized with a better taste.

Also, since shio koji contains salt and is salty, it can be used as a substitute for salt and soy sauce to reduce salt intake.

• Koji rice is rice that has been inoculated with Aspergillus oryzae
• Koji is Aspergillus oryzae which is a beneficial mold used in traditional Japanese fermentation processes
• Shio-Koji is a condiment made with koji rice, salt, and water.

HEALTH BENEFITS OF SHIO KOJI (KOJI-KIN)

Shio-koji is produced through a fermentation process by koji-kin aka Aspergillus oryzae, and like other fermented foods such as natto beans, miso, yogurt, pickles, and kombucha, it provides a variety of nutritional and health benefits.

Shio-koji is rich in nutrients such as enzymes, vitamin B1, vitamin B2, B6, GABA, essential amino acids, peptides, and kojic acid.

• Vitamin B1 plays a role in metabolism and brain function, helping the body metabolize carbohydrates, which has the function of efficiently supporting your energy.
• Vitamin B6 is involved in protein metabolism which has a role to make skin and mucous membranes healthy.
• Vitamin B2 is also involved in lipid metabolism against skin inflammation, so take it positively.
• Gamma-aminobutyric acid (GABA) can be expected anti-anxiety effects.
• “Gut health” is determined by the balance of the intestinal bacteria. Shio-koji has an enzyme that produces oligosaccharides for good bacteria, so continuously shio-koji in your diet, can be expected to improve gut health.
• “Proteases” that break down proteins and “amylase” that break down starch have the function of helping digestion.
• Prevention of arteriosclerosis may be expected by incorporating Shio-koji in your diet which has GABA, essential amino acids, and peptides.
• Kojic acid blocks UV activation, limiting the production of melanin which means it can help lighten existing sunspots and photodamage, fade the dark marks left from acne scarring or after a pimple, and even improve melasma.

1. Supports Digestion & Enhances Nutrient Absorption

The rich enzymes contained in rice koji (amylase, protease, and lipase) promote the digestion and absorption of nutrients in food. The fermentation process breaks down complex nutrients into simpler forms, so you can ingest nutrients efficiently.

2. Boosts Gut Health

The dietary fiber and oligosaccharides contained in rice koji increase the number of good bacteria in the intestines and improve the intestinal environment. It also has an immune-boosting effect.

3. Fatigue recovery effect

Glucose, which is decomposed from starch by the action of Aspergillus oryzae, and rich in vitamins promotes recovery from fatigue.

4. Promotes Skin Health

The amino acids and peptides contained in koji are thought to be effective in moisturizing and improving the elasticity of the skin, and koji extract is sometimes used in skin care. The B vitamins, such as vitamin B1 and folic acid, contained in rice koji promote blood circulation and metabolism. It is expected to have a skin-beautifying effect.

5. Rich in Umami Without Additives

Koji enhances flavor naturally, reducing the need for artificial seasonings, excessive salt, or sugar in cooking.

• Shio koji, Lemon Koji…use instead of salt
• Tomato koji…use instead of ketchup
• Tamanegi (onion) Koji…use as bullion
• Shoyu Koji, miso…use as it is, enhance flavor, instead of salt

How To Use Shio Koji In Cooking

• USE SHIO KOJI AS A TENDERIZING AND ENHANCED FLAVOR FOR MEAT AND FISH
• USE SHIO KOJI AS A SEASONING FOR ANY DISHES LIKE SOUP, GRILLING, STIR-FRYING, AND DRESSING
• USE SHIO KOJI AS PICKLING VEGGIES (TSUKEMONO MAKING)

Shio koji brings unique natural sweetness and aroma to dishes.

The most popular way to use shio-koji is by marinating protein foods.

As I said, shio-koji is a powerful tenderizer and enhancer that breaks down the protein structure into amino acids which is the component we feel “tasty”.

Especially, chicken and pork with shio-koji are perfect combinations, it can provide tener moist delicious chicken/pork by just marinating.

When marinating fish with shio koji, it can remove the fishy taste while adding umami flavor.

USE SHIO KOJI AS A TENDERIZING AND ENHANCED FLAVOR FOR MEAT AND FISH

When marinating meat or fish, spread about 10% of the weight of shio koji.

Wrap the meat /the fish in plastic wrap or put in a storage bag while removing the air, and marinate the ingredients in the fridge.

For small cuts, the marinating time is for 1-2 hours.
For the fish, it is for 15 minutes up to 30 minutes.
For a large portion of the meat, it is better to marinate for 8 hours through overnight.

USE SHIO KOJI AS A SEASONING FOR ANY DISHES LIKE SOUP, GRILLING, STIR-FRYING, AND DRESSING

It’s easy to use than you expected, and just try to use shio-koji instead of salt and soy sauce.

Throw a tablespoon of shio-koji into your regular soup such as chicken soup, tomato soup, minestrone, wedding soup, and beef mushroom soup!

I give you a recipe for a Japanese classic light soup called “OSUMASHI” which uses shio koji on the next page of this post, so you can check it out later if interested.

This Japanese soup is a super-light taste packed with Umami flavor from Dashi (hondashi powder) and Shio-koji, so you can add soy sauce or miso paste if desired.

Also, add your choice of protein such as chicken, pork, beef, shrimp, or tofu as the vegetarian/ vegan choice.

USE SHIO KOJI AS PICKLING VEGGIES (TSUKEMONO MAKING)

You can make Japanese-style quick pickles that mix with your choice of veggies and shio koji!

Shio koji brings out the flavor of the ingredients, making them Japanese-style pickles you won’t want to stop eating! Pickling for 2 hours will give you a quick pickles called “Asaduke” which is crunchy and light, while overnight pickles will give you a rich flavor.

Mix your choice of vegetables and 10% of the weight of shio koji in a container/store bag.

Jump to this post if you want to try making “shio-koji duke” Japanese-style pickles.

HOW TO MAKE SHIO KOJI

THE BASIC RECIPE

Ingredients:

• 200g dried rice koji *200g is 1.6 us cups. Around 7 oz
• 60g salt *60g is 4 tbsp
• 300,350,400ml water *300 mil is 1.2 us cup *350mi is around 1.5 us cup

1. Break up the lumps in dried koji if needed.
2. Mix the salt evenly with the koji.
3. Add the water to the salted koji.
4. Transfer the mixture to a clean container with a lid.
5. Cover the container loosely to allow some airflow.
6. Place the container in a cool, room-temperature place, about 68-77°F.
7. Wait and Ferment. Stir the mixture once daily.
8. Fermentation typically takes 7-10 days, depending on temperature. When you feel a sweet fruity aroma, it’s time to go!

ADDITIONAL TIPS

For the container, thoroughly clean and sterilize before use. It is preferred to a see-through container like glass and clear plastic so that you can check the fermentation process.

Salt is the key to making good koji rice, so use natural mineral salts such as sea salt and Himalayan pink salt.

For the water, use purified water.

Mix well the koji rice and the salt to combine the salt evenly with the entire mixture otherwise, it is a high possibility for saucerful to make shio koji.

I use a food processor so I don’t have to worry about it besides I can break lumps at the same time.

When adding the water to the salted koji, begin with 1.2 cups of water.

The mixture should be moist but not soupy. If adding water is too much, the salt concentration will decrease, causing decay and discoloration.

Avoid closing the lid tightly, and make room for the gas produced by the fermentation release.

Stir the koji rice once a day to redistribute the koji mold and lead the fermentation smoothly and evenly.

If the koji absorbs water and the water level goes down, add water each time.

Add just enough water until the koji is covered.

Generally, the fermentation will be completed in 10 to 14 days, but it may be slower when the temperature is below 20 degrees Celsius (68F).

When the rice grains are soft like porridge, it is ready to use.

You can leave the grains or make the paste if desired.

Store it in the refrigerator in a sealed jar. It can last for months (up to 6 months). However, it is better to consume within 1-2 months.

You can freeze Shio-koji, and it’s easy to use since it won’t be frozen completely.

The fermentation process will be inactivated in a freezer. However, the flavor will gradually be lost, so you should use it within 1-2 months (it’ll last for 6 months.)

When shio koji is repeatedly frozen and thawed, the deterioration rate will increase. Make small batches if you think you don’t use much at one time.

Shio-Koji Products You Want To Buy

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