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.
Is it ok to have mold growing on the surface?
Hi Cassie! No, it’s not okay, and you must remove it (if your mold can be removed). Sometimes it’s okay if you can remove it, but otherwise, it’s not safe to consume.
Should I put a cover on the jar? Or just cheese cloth? Thanks.
Hi Dan! You will need to put a cover on the jar. 🙂
Hi Nami,
I was wondering if this can be made in the Instant Pot using yogurt mode? Thank you.
Hi Lily, Yes. In Japan, some of the recipes use yogurt makers and cook for 6 hours.
However, we haven’t tested with Instant Pot. Let us know how it goes.🙂
I made my shio koji, the grains of rice are still prominent. It’s not a paste that can be spread on meats, I don’t see how this will work as a marinade? Would I better off putting the entire contents in a blender to make a smooth paste?
Hi Rob! Not necessary, but some people use a blender to make into a paste too. Most people use it without making into paste. 🙂
hello, thank you for your recipes. question: i didn’t mix my shio koji the first 2 days and it grew white mold on top. today I removed the mold and mixed. shio koji tasted fine. (i guess, it’s my first time). it also became very thick, so i added water to cover it. is this correct? also, where i live it is very hot right now (~35 C). maybe less than a week is enough? thanks!
Hi Dana! Ah…. sorry to hear about the mold. I’ve read somewhere that if there is mold, you can remove it and it should be okay (maybe if the amount is still small). Yes, adding water is fine. Sounds like yours should be done sooner because of the warm temperature too! Good luck!! 😀
Hi! Love your work!
I know this is kinda an old post.. but i’ve a few questions.
Can I make more shiokoji using cooked jasmine rice, salt, and a little bit of storebought shiokoji?
Kinda like I can make kimchi with fresh cabbage, salt, juices from storebought kimchi..
Hi Jetty! Thank you for reading my blog! No, it does not work with your method for this recipe. 🙂
Hi Ms. Nami!
I remember that there used to be a list of equipments that you use and links to buy them but I cannot find them anymore. Where can I find the link?
Thank you!
Hi JoAn! It’s under Shop on top navigation bar (same place):
https://www.justonecookbook.com/shop/
I updated this page recently. 🙂
Hello Namiko,
I am in brazil and almost sure i can not get koji rice here to prepare koji shio. Could i used another one? To use raw? We have kabocha here and yesterday i prepare the stir pork kabocha – very tasty too. I would like to know if there are also other recipes like the salads where i can used kabocha. Thank you in advance. Ingrid
Hi Ingrid! Shio koji or koji is pretty difficult to find, even in the U.S. It’s a specific ingredient that can’t be replaced… I hope this unique ingredient will be available one day… I’m happy to hear you like the stir fried pork & kabocha!
You might enjoy Kabocha salad? https://www.justonecookbook.com/kabocha-salad/
Or here are some of my kabocha recipes: https://www.justonecookbook.com/?s=kabocha
Thank you por answering and just today i noticed i should read the whole post instead only watching the video…the answer was already there! Sorry. The kabocha salad i prepared yesterday andi will prepare it many more times! I loved it. Thanks again. INgrid
Hi Ingrid! Don’t worry, as long as I have time I don’t mind answering. 🙂
If i find mold spots on the surface of my kojizuke base, is it okay to remove them and continue?
Hi Bronwen! You know, I or my blog can’t be responsible for making you sick. 😉
NO KIDDING, REALLY? I was asking a serious question. Sorry to annoy you.
Hi Bronwen! I wasn’t annoyed at all or mean to offend you. But please understand that I can’t recommend you to consume food that has mold spots without looking the actual thing. If it’s a white spot, some people remove and use it but it really depends on what type of mold. If it’s colored mold, it’s better to avoid. I can’t be responsible for saying yes and you get sick because of that. It’s kind of hard for me to give advice on this type of question. Sorry if you thought I was joking.
I found a jar of shio koji the back of my refrigerator that “expired about 4 months ago–so ~10 months since the shio koji was done. It still looks OK and doesn’t smell weird, and I just used a teaspoon and added to some sauerkraut I was making. Do you know how long shio koji can keep in a cold refrigerator? Just wondering. Thanks much for your wonderful site!
Hi Elise! I looked it up, and it looks like 1 month in the refrigerator and 6 months in freezer. I remember the exp date was pretty close when I bought a jar of shiokoji. But that’s recommended time, and you can see if it was bad or not by smelling etc. But yours seem a little too old…. 😀
Thank you so much for the recipe, am just wondering if i can use Himalaya pink salt to replace the sea salt in this recipe?
Hi Rose! I haven’t used Himalayan pink salt for this recipe, but it should work. 🙂
Can some of the Shio Koji be reserved to start a new batch, something like the mother starter for sourdough bread? The aspergillus appears to still be alive?
Hi Darren! I am not sure why, but I didn’t get this comment notification before. I apologize that I didn’t get to respond till now. I wasn’t sure, so I checked online.
It looks like you can add on. When the older shio koji is about 1/3 left in the jar. You can start making a new shio koji and when it’s 20% left, you can add that into the older shio koji. So… you still need to make a new shio koji… different from the bread or yogurt…
Hope this helps…
Can you add regular cooked rice to leftover shio koji without purchasing koji rice? Here where I live is hard to find koji rice, I only found shio koji and am wondering if I can make my own using store bought shio koji as starter?
Hi Klaudia, Thank you very much for trying Nami’s recipe!
We heard some people tried it but not sure how it turned out. We are sorry we couldn’t be more helpful😞
Hi
I was on day 3 of making homemade shio koji and i stirred it once each day and today i noticed a dried white flaky film on the top of it when i opened the container. It smelled of ammonia and i had to toss the shio koji. Do you know what might have went wrong?
Hi Cal! I have never had this issue, so I looked it up on Internet (in Japanese). Thank you for describing the condition well. According to several sites I looked, (especially if you used the dried koji,) it is possible to have white film on top. You can mix it up or scoop that part out to discard, and see how it goes (just in case it was something bad). And regarding the smell, the smell you described seem to be safe one. Some brand of koji smells even more than others. All these situations mostly happened in the summer/warmer months. Is the place you live in summer season now? Hope this helps!
I am trying to make the home made “shio koji” using your recipe using 7 ounces of the dry rice koji, 4 TBS of sea salt, and I cup of warm distilled water. I used a portable electric mixer to thoroughly mix the ingredients before placing it in a heat sterilized glass jar and will age it for a week to ten days mixing it once a day. What is the proper consistency of the finished, aged shio koji? The commercially made shio koji seems to have a liquid consistency that it can poured out of the container. Should I add more water to the mixture or will the finished product gradually become liquid in consistency as it ages? Thank you in advance for the information and advice.
Hi Edwin! You can add water as you like and make sure the koji is submerged all the time. Each shio koji brand I tried has different consistency, so I think it’s up to you how you want to make it. Koji will absorb more water everyday, so keep adding water. 🙂 Hope you enjoy!
First of all I would like to wish you a Happy New Year. Your recipes are great, and you are a wonderful teacher. I am 63 years old and still love to learn new cooking skills. Thanks for sharing and have a fantastic day.
Hi Grace Bobby! I’m really happy to hear you enjoy my recipes, and thank you so much for reading my blog! Have a great week ahead. Thanks for your kind comment! 🙂
Alright. I decided that I want to try this. I’m going to search for a website that ships koji to Sweden. For I know no Japanese or Asian grocery stores within my vicinity.
Thanks for sharing Nami, I tried your beef curry recipe today. It was great.
Hi Albert! I really wish you can find koji…. which could be still difficult without a Japanese store. Thank you for trying out the curry recipe! I recently took new pictures of it (and video!) and hope to update that old recipe soon…. 🙂