Shio Koji 塩糀

Updated 30th April 2022.

I stumbled upon the world of koji (糀 or 麹) a year ago while I was researching the traditional method of soy sauce making. One thing led to another and here I am 10 months later an avid fan of shio koji. While my dream of making traditional fermented soy sauce is on a halt, I am learning to make other Japanese fermented food that utilizes koji. Shio koji is one of the easiest fermented food you can make at home.

Shio Koji 塩糀 (Salt Koji)
Shio koji 塩糀 is ❤️❤️❤️

Shio koji 塩糀/塩麹 or salt koji aka umami salt is fermented koji in salt. It’s made of koji, salt and water. Shio koji is an ancient Japanese seasoning. What’s so special about shio koji? Everything it touches receives a boost of umami! This is due to the protease enzyme in koji that breaks down protein in the ingredients into amino acids and one of the key amino is glutamate which gives umami and it also tenderizes the ingredients. Shio koji also brings out the sweetness in the ingredients when amylase breaks down the starch to sugar. Shio koji is used in place of regular salt to season, to marinate and as well as tenderizes meat to a juicy outcome and as a pickling agent and then more!

You must be wondering what is koji 糀/麹. Let me briefly explain. Koji is from the fungi kingdom of the genus Aspergillus and it’s a type of mold. Koji is the fermentation starter for the production of traditional Japanese seasonings and alcoholic + non-alcoholic beverages like miso, shoyu (soy sauce), sake, shochu, mirin, rice vinegar, amazake and as well as shio koji.

Koji spores are grown on a medium like white rice in which the resultant product is called 米麹 kome koji/koji rice, brown rice (玄米麹 genmai koji), soybeans (大豆麹 daizu koji), wheat (小麦麹 komugi koji), barley (大麦麹 ōmugi koji), etc. For example, kome koji is grown from koji starter that contains the fungus Aspergillus oryzae on cooled steamed rice under a controlled environment and is used to make sake, amazake and shio koji. Daizu koji meanwhile is grown from Aspergillus sojae on soybeans and is used to make the likes of soy sauce and soybean miso.

Aspergillus Oryzae
Is it a flower? 🌸 No, it’s Aspergillus oryzae! So important is this fungus in Japanese culture that it’s named the national fungus (国菌 kokkin).
Photo source: https://www.marukome.co.jp/koji/

Have you noticed I’ve been writing koji as 糀/麹? Both means koji. The difference is that 糀 is a kanji character created in Japan during the Meiji era. If you’re able to read Chinese characters, you’ll notice that there’s 花 in 糀 which means flower. This is because the Aspergillus filamentous spores that are growing on the steamed rice look like blooming flowers (refer photo above). Meanwhile, 麹 is a Chinese character from China and take note that it contains 米 (rice) in 麹. With that said, 麹 is widely used today and 糀 is used by koji specialty shops. I hope this short explanation is able to give you a peek into the world of koji.

Now back to shio koji.

The most important ingredient to make shio koji is of course the koji. There are fresh (raw) koji and dried koji. Fresh koji has a short shelf life (~2 weeks refrigerated and no freezing). To obtain it may also be difficult especially when many of us don’t live near a place selling/producing it. Dried koji is dehydrated fresh koji and it has a long shelf life (~3 months refrigerated & more than a year frozen). Some say not to freeze the dried koji as it could reduce its potency (weaken the fungus). You can easily get dried koji from online shops nowadays. Some Japanese specialty stores carry it too.

p/s: I freeze my dried koji as I have no room in the fridge. I will update if I ever use refrigerated dried koji to make shio koji and compare them.

For this shio koji recipe, I’m using dried koji rice/kome koji. You can also use genmai (brown rice) koji where the flavors will have more depth.

Dried Koji Rice
In a cleaned glass jar, add the dried koji rice. I always use a clamp lid glass jar. If the dried koji rice is clumped up, simply use a spoon or chopstick to separate them in the jar.

Dried Koji Rice
It’s still okay if the dried koji rice is not separated into individual grains 100% at this stage.

Mix Dried Koji Rice With Sea Salt
Next, add fine sea salt and mix well. I use Celtic Sea Salt® brand as it’s natural and rich in nutrients and minerals.

Add Water To Dried Koji Rice & Sea Salt
Pour room temperature water into the glass jar. The water must be boiled and cooled to room temperature. Using hot water will destroy the koji’s enzymes and nutrients.

Mix Dried Koji Rice, Sea Salt & Water
Mix really well so that all the dried koji rice grains are separated and sea salt is diluted in the water. The liquid will look milky and a little yellowish.

During fermentation, gas may be released, hence we do not want to tighten the lid. If using a regular glass jar, lightly seal the lid. If using a clamp lid glass jar (like mine), place a cloth over the jar mouth, remove the rubber gasket and clamp the jar. I usually don’t use a cloth but in one of the batches, bugs were found inside the jar. As not to risk the precious koji again, I use a cloth to cover from thereon.

The glass jar is placed at room temperature away from heat. In warm weather, fermenting takes about a week while in cold weather it’ll take about 2 weeks. Fermentation is sped up in warm conditions. For a more complex flavor, ferment for a month or more. You will also need to stir the solution daily. Please refer to the recipe down below for the full steps and explanations.

Shio Koji 塩糀 (Salt Koji) Day 7 - Before Stirring
This is shio koji on day 7 (before daily stirring).

Shio Koji 塩糀 (Salt Koji) Day 7 - After Stirring
This is shio koji on day 7 (after stirring). When the shio koji smells savory with a hint of sweetness and it tastes mildly salty, that means it’s ready to be used.

Shio Koji 塩糀 (Salt Koji)
Pour the shio koji into a cleaned air-tight glass jar. Store in the refrigerator for 6-10 months or 1 year in the freezer.

Shio Koji 塩糀 (Salt Koji)
The koji rice grains which was whole initially have broken down after a week in warm weather. It looks just like porridge and is light yellow/beige in color (from the koji mold, also depends on the type of koji that you used). On day 1, the solution is very salty. It will then transform into umami, have a milder saltiness with a light sweetness to it and ricey/yeasty scent on day 7. You can use the shio koji as is. Just stir it before using it as the grains will settle at the bottom.

If you prefer the shio koji to have a smooth consistency, you can puree it. So far, I have not found any difficulties while using the shio koji as is. Besides, the broken koji rice grains have an aesthetic appeal to them.

Shio Koji 塩糀 (Salt Koji)
Homemade shio koji contains active live enzymes and is rich in probiotics and nutrients. It makes the food delicious and healthy and it’s good for us when we consume it. Many shio koji in the market are pasteurized = enzymes and probiotics are dead and nutrients are greatly reduced.

As mentioned earlier, this umami-rich seasoning is used to season dishes, marinate, tenderize meat, fish or tofu and as a pickling agent. From the first moment I use shio koji in my dish, my life was never the same again. My cooking has elevated since I use shio koji. It makes my food taste more savory (umami) and lip-smacking good (not that it tasted bad before) and overnight marinated meat is extremely juicy. It’s all thanks to the enzymes. 😋🤤 I’ve even used shio koji in soup and marinated siu yuk with it. Listen, you can never be wrong when you use shio koji for everything and anything. I’ve been using shio koji in all my cooking since I make my very first shio koji. There’s no turning back nor do I want to go back to using regular salt in my cooking. Next, I will try using shio koji in my baking.

p/s: Before shio koji, I’ve found that using lard in my cooking will boost my dishes to a new level. Can you imagine what it would be like to use shio koji and lard together? I’ve married both the ingredients and my dishes are on 🔥🔥🔥!

Shio Koji 塩糀 (Salt Koji)

As to how much shio koji to use in your dishes, it’s a big mystery. 😛 Actually, I can give you an estimate but I figure it’s best to gauge it yourself. My definition of salty is definitely different from yours. Just like with regular salt of different sizes and saltiness where you need to estimate how much to use initially, the same goes for shio koji. Agak-agak (estimate) at first. Once you get the hang of it, you’ll use shio koji like regular salt without blinking. I will share recipes using shio koji in future posts. If you follow my shio koji ratio, you can then follow the recipe provided.

Do you know that there’s another famous Japanese miracle seasoning besides shio koji? It’s non-other than shoyu koji. Check out the recipe here.

Thank you so much for reading this lengthy post. Please try the shio koji recipe below and apply it to your cooking and baking. Let me know how you find your dishes made with shio koji. If you’ve used or are using shio koji in your kitchen, please share with us your tips.

Updated April 2022:
Shio Koji 塩糀 (Salt Koji)
I usually make shio koji with kome koji but recently, I made it with genmai koji. I have not used it yet but from tasting it during daily stirring, I already could gauge how awesome it’s going to be when used in my cooking. After fermenting it for 2 days, already I could taste the meatiness – my own sign of a delicious ferment out of it.

Shio Koji 塩糀
Inspired by & adapted from Cooking With Koji
Yields about 480g

200g dried/fresh koji rice (kome or genmai)
60g fine sea salt (salt is 30% of koji weight)
250ml room temperature water (boiled)

700ml or higher capacity regular glass jar or clamp lid glass jar

*Depending on the koji rice brand/manufacturer, recipe ratio, etc, the outcome of the shio koji will be different.

1. Place koji rice in a cleaned glass jar. Use a spoon or chopstick to separate the clumped up koji rice, if any.

2. Add fine sea salt and mix well.

3. Pour water and mix until well combined. Make sure the koji rice is separated into individual grains.

4. As gas may be released during fermentation, do not tighten the jar lid. For a regular glass jar, lightly seal the lid. For the clamp lid glass jar, cover the jar mouth with a piece of thin cloth, remove the rubber gasket and then seal the lid.

5. Place the glass jar at room temperature away from the heat source. Fermentation time is ~1 week in warm weather and ~2 weeks in cold weather. For a deeper and more complex flavor, ferment for a month or more.

Important: During fermenting, stir the solution daily with a clean wooden/ceramic spoon and then taste the solution from the remnant of the utensil. On the first day, the dried koji rice will swell (rehydrated – as it has absorbed the salt+water) and it will look like there’s not enough water. No worry. Just stir it to ensure an even mix. As the solution settle (due to it being stationary), the koji rice will descend to the bottom. Daily stirring will ensure the solution is cultured evenly and tasting it daily will allow you to experience the transformation day by day.

6. From a very salty solution on day 1 to tasting umami, mild saltiness, light sweetness and smelling ricey/yeasty a week/two weeks later, the shio koji is now ready to be used. The koji rice also breaks into smaller sizes after a week/two weeks of fermentation. Transfer the alive enzymes-rich shio koji to a clean air-tight glass jar and store it in the refrigerator. It can be kept 6-10 months in the refrigerator and 1 year in the freezer. Use a clean wooden/ceramic spoon to stir it first before scooping the shio koji for use as the koji rice will settle at the bottom of the jar. The shio koji will continue to ferment in the fridge but it will slow down due to the cold temperature. As time went by, the koji rice grains will break down further.

7. As with using any seasonings including the various kinds of salt, you would need to agak-agak (estimate) when using shio koji initially. Once you are able to gauge how much shio koji to use, everything’s a breeze. If you follow my shio koji recipe to make shio koji, you can then follow the amount used for future recipes that use shio koji.

Happy koji-ing!

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