Shio koji (塩麹) is a fermented all-purpose seasoning made from kōji, salt and water. As it sits, the kōji enzymes turn the rice's starch into gentle sweetness and its protein into savoury amino acids, giving a paste or liquid that seasons and tenderises in one step. It is the easiest way to cook with kōji.
This is our guide to shio koji, written for chefs and curious cooks alike: what it is, how it is made, the paste and liquid forms, and how a kitchen uses it to season and tenderise. It is part of our wider kōji guide and sits inside our Fermented Masterclass.
What Is Shio Koji?
Shio koji (塩麹) is a fermented seasoning made by combining rice kōji (rice cultured with the mould Aspergillus oryzae) with salt and water and leaving it at room temperature for roughly one to three weeks. The name is literal: shio (塩) is salt, kōji (麹) is the mould-grown grain. The result replaces plain salt with something deeper.
The kōji is the same yellow kōji used for sake, miso and soy sauce, and in shio koji its enzymes work directly: amylases break the rice starch into sugars for a gentle sweetness, and proteases break protein into amino acids including glutamate, the source of umami. The salt, typically around 10 to 13% by weight, seasons the mixture and keeps it stable while the enzymes do their work. Full background on the culture itself is in our kōji guide.
For a chef, the useful way to hold shio koji is as a seasoning that also tenderises: one spoonful brings salt, a rounded savoury sweetness and enzyme action that softens protein, which plain salt cannot do.
Source: NRIB material on the kōji enzyme mechanism (via the kōji parent record), facts extracted and reworded; the salt level is standard for this class of seasoning.
How Is Shio Koji Made?
Shio koji is made by mixing rice kōji, salt and water and holding it at room temperature for about one to three weeks, stirring occasionally, until the kōji enzymes have saccharified the rice and softened the mixture into a thick, fragrant paste. The transformation is enzymatic, not a yeast or bacterial fermentation, so as with all kōji products the strength and balance of the kōji's enzymes set the quality of the result.
The salt does two jobs: it seasons, and it keeps the mix stable over the holding period so the enzymes can act cleanly. Strained of its solids, the paste becomes a clear liquid shio koji, which is easier to pour and measure. Either form is then used in place of salt.
For a chef, the takeaway is that shio koji is a living, enzyme-driven seasoning, so it keeps working on whatever you add it to, which is exactly why it tenderises and why timing matters.
Source: NRIB material on kōji-enzyme saccharification (via the kōji parent record), facts extracted and reworded. Exact commercial salt percentage, strain and schedule for individual products are not in our records.
Paste and Liquid Shio Koji
Shio koji comes in two forms, and they suit different jobs. Paste shio koji is the traditional, home-fermented form: thick and spoonable, ideal as a marinade or rub where you want it to cling to fish, meat or vegetables. Liquid shio koji is strained smooth and pourable, which makes it easier to fold into dressings, soups and brines and simpler to portion in a busy kitchen.
Both deliver the same enzyme action; the choice is about handling. Our active supplier Hanamaruki produces a liquid shio koji in a foodservice format, while paste versions come in kitchen and home sizes. A kitchen often keeps both: paste for marinating, liquid for everything pourable.
Source: form distinction from Hanamaruki KC Central product information and standard industry use; paste-versus-liquid handling is established practice.
Popular Products
Four shio kojis, across liquid and paste and from kitchen to foodservice size:
Hanamaruki Liquid Shio Koji, 500ml
The pourable liquid shio koji from our active supplier Hanamaruki: smooth and easy to measure, for brushing onto fish and meat or folding into dressings and brines. The simplest way in.
Marukome Raw Shio Koji (Nama Shio Koji), 500g
Live paste shio koji in the kitchen-size pack: the traditional rub for curing and marinating, where the active enzymes tenderise protein and deepen savoury flavour. The workhorse paste.
How Chefs Use Shio Koji
Shio koji's signature use is as a marinade that seasons and tenderises at once. Brush or rub it onto chicken, fish or pork an hour or up to a day ahead: the proteases break protein down for a softer, juicier texture while the amylases add a rounded, savoury sweetness, a cleaner and deeper result than salt alone. Roughly a tablespoon per portion is a sensible starting point.
Beyond marinating, it works as an all-purpose seasoning in place of salt: stirred into dressings and dips, added to soups, brushed on vegetables before roasting, or used in a quick pickle. Liquid shio koji is the easiest for anything pourable; paste is best where you want it to cling. Because it keeps acting, watch the timing on delicate fish so it does not over-soften.
Our steer for a working kitchen: keep a liquid shio koji as a default seasoning and tenderiser, treat it as both salt and a marinade, and dial the quantity and time to the ingredient. (Specific quantities and timings here are our own kitchen practice; the record flags chef-level detail as a gap.)
Source: marinade tenderising and umami from NRIB material on kōji enzymes (via the kōji parent record); broader applications are widely established uses and SushiSushi practice rather than a single cited source.
Frequently Asked Questions
What is shio koji?
Shio koji is a fermented Japanese seasoning made from rice kōji, salt and water, left to mature for about one to three weeks. The kōji's enzymes turn the rice starch into a gentle sweetness and its protein into savoury amino acids, giving a paste or liquid used in place of salt that both seasons and tenderises.
What is shio koji used for?
Most often as a marinade: rubbed onto chicken, fish or pork ahead of cooking, it tenderises the protein and adds umami. It also works as an all-purpose salt replacement, stirred into dressings, soups and dips, brushed on vegetables before roasting, or used in pickling. Liquid shio koji suits pourable jobs; paste is best for marinating.
How do you use shio koji to marinate meat or fish?
Coat the protein in shio koji, using roughly a tablespoon per portion, and leave it from an hour up to about a day in the fridge. The enzymes soften the texture and build savoury flavour as it sits. Wipe off the excess before cooking, as the residual sugars can catch and burn. Keep delicate fish on the shorter end so it does not over-soften.
What is the difference between paste and liquid shio koji?
They are the same seasoning in different forms. Paste shio koji is thick and clings well, ideal as a marinade or rub. Liquid shio koji is strained smooth and pourable, easier to measure and to fold into dressings, soups and brines. Both deliver the same enzyme action; the choice is about handling.
Is shio koji the same as kōji?
No. Kōji is the raw mould-grown grain, the culture itself. Shio koji is a finished seasoning made by combining that kōji with salt and water and letting it mature. So kōji is the ingredient and engine, and shio koji is one of the easiest ready-to-use ways to cook with it. See our kōji guide for the full picture.
Where to Buy Shio Koji in the UK
If you are looking to buy shio koji in the UK, we keep a range with fast delivery across the UK, in liquid and paste forms and from kitchen jars to foodservice packs. Start with a liquid shio koji if you simply want to season and tenderise tonight.
For more, read our kōji guide, browse the Fermented Masterclass, or read about miso and soy sauce, the other ferments kōji makes possible.
Technical material sourced from the SushiSushi Knowledge Base record store/koji/shio-koji.md and its parent store/koji/koji.md. The kōji-mechanism facts are sourced from the National Research Institute of Brewing's published material, separately copyrighted and fact-extracted here, not reproduced; product facts are from Hanamaruki supplier information. The enzyme mechanism is established food science.
