Japanese Ingredient Highlight: Shio koji (塩麹, 塩糀). A century-old natural seasoning used in Japanese cooking to marinate, tenderize, and enhance umami flavor of a dish. Learn more about this all-purpose seasoning.
It’s been several years since Shio Koji (塩麹, 塩糀) experienced a huge resurgence in popularity as a versatile seasoning in Japan. This page is about shio koji, its benefits in cooking, and how to make it at home.
What is Shio Koji?
Shio koji (塩麹, 塩糀) is a natural seasoning used to marinate, tenderize, and enhance the umami, or richness (one of the five basic tastes) in foods. It’s made of just a few simple ingredients: salt, water, and rice koji.
Rice koji (米こうじ, 米糀, 米麹) is steamed rice that has been treated with koji mold spores (Aspergillus oryzae, koji-kin 麹菌, or koji starter). Koji is a specific strain of mold that has been cultured over the centuries.
You may feel hesitant to eat it and wonder why we make rice moldy on purpose. But you have most likely eaten it already!
Koji has been the key ingredient in making miso, soy sauce, sake, mirin, rice vinegar, amazake, shochu, and shio koji. It’s a live food that is rich in enzymes that break down starches and proteins in food into sugars and amino acids.
You can use shio koji to marinate meats, make pickles, flavor your vegetables or use it as a salt substitute. In a recipe that calls for one teaspoon of salt, you can substitute with 2 teaspoons of shio-koji. Shio-koji is really versatile and can be used in any kind of cooking (See Shio Koji recipes)!
Benefits of Shio Koji
Because it is a fermented ingredient, shio koji is known for its many health benefits, which include (source):
- A natural pro-biotic seasoning
- Tenderizes food
- Brings out the umami and sweetness in foods
- Reduces the intake of salt
- Aids for digestion
- Clear the skin
- Anti-aging
- Contains minerals, fiber, and vitamins
How to Make Shio Koji at Home
Yes, you can make shio koji at home as it only involves a few ingredients. You can check out my quick video that demonstrates the process. For a step-by-step recipe, read on in the recipe section below. I hope you have fun making Shio Koji at home and discover more ways to flavor your dishes with this amazing ingredient!
Recipes with Shio Koji
Where Can We Find Rice Koji?
Rice koji can be found in Japanese grocery stores or online. I found the following Japanese brand in a Japanese grocery store.
Resources
To read more about koji, please read here, here, here (Japanese), and here (Japanese).
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How To Make Shio Koji
Video
Ingredients
- 200 g rice koji (7.05 oz)
- 4–5 Tbsp sea salt (can be 10–30% of koji quantity; do not use table salt)
- 1 cup water
Instructions
- Gather all the ingredients.
- In a large bowl, break 200 g rice koji and separate the koji grains into smaller pieces.
- Rub the koji firmly in your hands to separate into individual grains.
- Rub the koji until aromatic, add 4–5 Tbsp sea salt, and mix all together.
- Add 1 cup water. If necessary, add more water if it doesn‘t cover the surface of the koji. Rub the koji with your hands.
- Transfer to sterilized jar(s)/container with a lid. Make sure the shio koji is submerged in water; if not, add more water.
- Ferment the shio koji at room temperature, open the lid and mix it once a day for 1 week during the summer and 2 weeks during the winter (as warm temperature speeds up the ripening process). Add a bit of water if the shio koji is too hard. It might taste salty at the beginning, but it will gradually become mild. Shio Koji will become thicker and begin to smell sweet from the fermentation.
To Store
- Store in the refrigerator for up to 6 months.
I bought some “liquid” shio koji from Amazon and I received it today in a box. It says on the bottle “Keep refrigerated,” not just “Refrigerate after opening.” I’m afraid to use it now. Am I wrong in my thinking? Is it okay if it’s unrefrigerated before opening?
Hi Jason, Store-bought liquid Shio Koji can be in a cool place (not refrigerated) before opening. The Hikarimiso website also shows, “Avoid direct sunlight and store in a cool place.” We hope this helps!
Thank you very much for this recipe. I am wondering, is it ok to use a Pyrex container with plastic lid for storage instead of a mason jar? Thank you!
Hi Alex, Sure, you can use that. Thank you very much for trying this recipe!
I have genmai koji, will it still work with your instructions?
I would also love for you to write more about using koji. I would love to learn the differences between the white, brown rice and barley varieties.
I know you can also make soy sauce based shio koji (hishio). Do you have instructions for that?
Hi Kitty! I wish I know more about koji but to be honest I am not an expert. Have you read these koji books?
https://amzn.to/2SOE2BW
https://amzn.to/3dn9z7z
Hi, I m excited to try recipe. It wasn’t mentioned what u used to cover jar while fermenting. Lid, cheese cloth, plastic wrap?
Hi Nancy! Just the jar lid, but you open the jar every day to mix. 🙂
I’m making a batch of both shio and shoyu koji. I’m about one week into fermenting both. The shoyu koji just smells like shoyu (no big surprise there), but the shio koji does not smell very appealing. It smells like my rice cooker if I left my rice out for too long. Is that a normal aroma for shio koji? I tasted it, and surprise, it tastes sort of like salty, bad rice.
Does this smell and flavor mellow out and change over time?
Hi Jessica! Unlike shoyu that gives umami, shio koji is “salty” but because of koji it is more mellow, mild taste. I looked up in Japanese to see what we can do and some recommended that it should be fermented at room temperature more before moving to the refrigerator. Hope it will come out well!
I did some Shio-Koji and experiment a lot with it. It taste pretty good – yet I don’t see the life-changing results which it is praised for.
Now a couple of months “in”, the jar in my fridge developed even a clear layer which looks like commercial liquid Shio-Koji…
My problem: I don’t see any tenderizing properties at all. It is rather the opposite: chicken cooked sous vide with sk isn’t as tender as chicken cooked without sk. Also without SV I barely see a difference. It browns faster for sure; but it is for sure not more tender… is it only me?
Also I would love to see more veggie (and other) recipes with Shio Koji…
Hi Dominik! Enzymes cultivate the protein on the surface of the meat and this breaks down the protein on the surface of the meat. Well, that’s the theory… Have you tried it with different types of meat? How about beef?
Hi Nami,
Hello from Oakland.
This is amazing umami!
Great for salad dressings and soup.
I have a question. I usually purchase koji already made and it is very creamy.
My home made batch is more grainy.
Would it be alright to blend finished koji to make it smoother?
Thanks for the instructions!
Jef
Hi Jef! Thanks for trying this recipe! I’m glad to hear you liked it. And, Yes, you can. 🙂
I just made this! I’m wondering though, it just has to stay at room temp for 1-2 weeks then we move the jar to the refrigerator, is that right? Thanks for all your recipes! I’m making the umeshu next 🙂
Hi Tiff! That’s correct (but depending on the temperature/climate you live in). I look forward to making Umeshu this year too! 🙂
Konichiwa, thanks for your inspirations and sharing your recipes! I mixed everything up (koji, salt and water), put in a jar and stirred daily for two weeks. I had to take a last-minute trip abroad and was gone two weeks, and didn’t refrigerate it. So, the jar was left at room temperature for a total of about four weeks instead of the recommended two, but I put it in the fridge as soon as I returned home. My flat is normally about 21 or 22 C. It looks like shio koji should look and doesn’t smell bad or anything. Do you think it’s spoiled or unsafe to use? I don’t want risk getting botulism or food poisoning. Should I throw it out and start over or is it salvageable? What do you think? Please help. Thank you so much again for any guidance!
Konnichiwa labelleduchesse! No bad smell or no visible mold is a good sign. All the “recommendation” online says it’s up to your judgement. So I can’t really tell… Salt content is pretty high so I think it preserves well. Try using small amount 1 Tbsp to marinate or replace regular salt and see how it goes?
Hi Nami, I am starting to make Shio Koji from a recipe belonging to Holly Davis who is the author of “Ferment”, a great book covering many ways of fermenting foods, including Koji and sourdough and more! Her recipe is so different from yours. It starts with 200grams of Koji rice, but then is 35grams of sea salt and 330 mls of water. The salt content is so much less than yours, and I am concerned about that. 35grams of sea salt is around 2 or 2.5 tablespoons (US tablespoons rather than British or Australian measures). An Aussie tbsp = 20mls compared to US of 15mls. Four tsp compared to three! Do you think the lower salt content will be okay? Thank you so much for sharing your recipes! I made the egg salad sandoichi for our older persons’ group and they loved your version of kewpie mayo! They say your mayo is the best and your egg salad is the best they have ever had. They told a local chef that “Gay’s egg salad” (your recipe) is better than his! Your pickled ginger is now the only one we use and we never buy the supermarket version, even when making recipes for the older persons’ group! They like yours better and call you “Nami Numm Numms”
Hi Gay! Thank you for your sweet feedback. I’m so happy to hear the group enjoyed the sandwich! And you like the pickled ginger. 🙂
As for the shio koji… I’m not sure about her recipe. I studied how to make shio koji in Japanese but I’m not sure how others would make it to be honest. Sorry I wish I could give you some feedback… 🙂
Thank you for this. I was wondering how to store koji rice.
thanks
Len
Hi Len! You’re welcome! 🙂
[…] Just One Cookbook — How to make Shio Koji […]
I often see a Chinese product called “sweet fermented rice,” in asian grocery stores, do you know if it is similar to shio koji?
Hi Corrine! It’s different: https://thewoksoflife.com/sweet-fermented-rice-jiu-niang/
thank you so much! I hope this didn’t inconvenience you too much
Hi Corrine! Not at all! 🙂 Please feel to contact me anytime. I’m in Japan traveling, so my response has been a bit slower than usual. 🙂
[…] If you’re new to shio koji, you can read more about this magical ingredient on this page about shio koji. […]
I was having a little root around Tomiz in Nagoya yesterday and came across the rice koji, plus the package of pre made shio koji. I picked one up without knowing what to do, but having a feeling you might! Lo and behold, I find your recipes … I used it as a rub/marinade for some chunks of beef before drenching in flour and searing for use in a stew. Delicious, a subtle but noticeable difference to just using ‘salt’. Thanks Nami!
Hello Cyn! I love Tomiz! Yeah, Shio Koji is amazing! We can definitely notice the difference when we use shio koji. I love to replace it with salt to season or marinade. 🙂