Impress your friends and save money by making your own soy sauce from scratch. Today we’ll learn how to make a homemade shoyu, a fermented soy sauce made from soybeans and wheat berries.
This post has been in the making for several years now. Yes, years!
I’ve had several failed attempts before finally reaching success and making a wonderful soy sauce with complex flavors. Fortunately, my failures were due to misinformation more than they were to a complicated process. Making your own soy sauce does require some patience, but it really isn’t that difficult.
When I first started trying to make my own soy sauce, there wasn’t a lot of information on the web, and the only posts about the process showed people making patties out of soy and letting them grow mold from whatever wild molds might be present in the air. Many of these “recipes” were based on people watching their Asian relatives make soy sauce at home. I guess the whole process sounded a bit risky, but since it’s quite common for people to make sourdough starters from the wild yeasts in the air, I thought the idea had some merit and decided to give it a try. (I mean soy sauce making had to start somewhere, right?)
The problem?
Making soy sauce is a long process, and each time you give it a failed shot, you end up wasting a lot of time.
I tried making a homemade soy sauce with local wild molds, and while trying it didn’t kill me, it didn’t impress me either. Maybe it has something to do with the fact that the wild molds and yeasts here in Spain are different than those in the soy sauce making regions of Asia. (From a bit of further research, it appears that making soy patties that collect local molds is most typical in Korean soy sauce making.)
The process of making it wasn’t easy sailing either. I had to endure foul-smelling moldy soy patties (not to mention my husband’s complaints about the odor.)
We’ll just say that my first homemade soy sauce wasn’t good enough to share on the blog. Just as sourdough starters will vary from region to region, not only can a wildly propagated soy sauce have a lot of variances, but it could be potentially dangerous. That’s why you need to start with a specific fungus for inoculating your batch. Luckily, using a starter fungus also makes for a much more pleasant soy sauce making experience. (Yes, it smells much better too!)
Watch How to Make Soy Sauce (Homemade Shoyu)
What is Soy Sauce?
Soy sauce is a thin, liquidy, Asian condiment normally made from fermented soybeans. Specific strains of fungus are grown on soybeans, and then the mixture of fermented soybeans is allowed to continue to ferment within a salt brine.
Soy sauce varieties vary from region to region, and not all modern day soy sauces are actually even fermented anymore. Most store-bought soy sauce will be pasteurized, too, so it’s great to be able to make your own and add one more unpasteurized fermented food to your pantry. (Plus, if you use a lot of soy sauce, you can save a lot of money with this one!)
What is Shoyu?
Shoyu is the Japanese term for the type of soy sauce that is made with both soybeans and wheat. It is normally what we are used to seeing when we think of “normal” soy sauce.
Shoyu differs from Tamari, another type of soy sauce, in that tamari uses little to no wheat and is sometimes fermented with a different strain of fungus (Aspergillus tamari). Tamari began as a byproduct of making soybean miso. It was the liquid that pooled up on the miso. Nowadays, though, with an increased demand for a wheat free soy sauce, companies work to make more tamari as a stand-alone product.
Is Soy Sauce Vegan?
People often ask this question, and the answer is Yes! Soy sauce is vegan.
Soy Sauce Ingredients
Soy sauce only uses soybeans, wheat, salt, water, and the strain of fungus desired for fermentation, normally Aspergillus oryzae or Aspergillus sojae. Aspergillus tamarii is sometimes used for making tamari.
On my very first attempt at making soy sauce, I went to the health food store and bought the only soybeans that were for sale at that particular store. They were small, green soybeans and didn’t make as nice of a paste or sauce.
I later saw that you could buy either larger white (beige) soybeans or the tiny green ones. It turns out that the beige soybeans are more mature soybeans, and the green soybeans are younger. The mature soybeans are the ones that are normally used to make everything from soy milk to, well, soy sauce.
How is Soy Sauce Made?
Homemade Soy Sauce (Shoyu)
Makes around 1 gallon
Ingredients
- 1200 g dry soybeans (the white or beige type)
- 1200 g wheat berries Soft wheat gives better flavor than hard wheat
- 7.5 g aspergillus orzyae starter meant for shoyu
For the Brine
- 825 g sea salt
- 3.8 liters water
Instructions
Prepare the soybeans
- Rinse the soybeans and cover them with water in a large glass jar or another suitable container. Keep in mind that they will double in size when they absorb the water.
- Soak them overnight, or for 12- 16 hours. (Add more water, as needed, to allow them to fully hydrate.) Notice in the photo that they have doubled in size once hydrated.
- Drain the soybeans and cook them by steaming them in a pressure cooker for an hour and a half, or cook them in boiling water for around 6 hours. A slow cooker is a good option in that case.
I used a pressure cooker and poured water in the bottom of the pressure cooker. I then put a stainless steel steamer basket over the water and filled the basket with the soaked soybeans. I set the pressure cooker to cook for an hour and a half. - When fully cooked, you should be able to easily crush the soybeans with your fingers.
Prepare the wheat
- Brown the wheat berries in a skillet for several minutes until they turn golden brown. You can also broil them in the oven, spread over a baking sheet, stirring every couple of minutes to prevent burning, if you prefer.
- Grind the wheat coarsely using a food processor, grain mill, or another type of grinder. You are aiming to break each grain into several pieces. You don’t need to completely pulverize the wheat berries into powder.
Preparing the koji
- Mix together the ground wheat berries and the cooked, drained soybeans in a large mixing bowl. Allow the mixture to cool.
- Sprinkle a koji starter over the wheat and soy mixture and thoroughly incorporate it into the mixture.
- Spread the inoculated mixture over glass or stainless steel trays or bowls. (Use something with a broad base so that you can spread out the shoyu koji.)
Make furrows (small valleys) in the mixture every 2 inches or so to avoid having thick layers where hot spots emerge. (Hot spots are areas where the mold gives off too much heat.) - Place a thermometer in the koji and cover the trays with either a plastic wrap or a tight weave cloth to help keep the moisture inside. Incubate the trays at around 85ªF (32ºC). (I used my oven with the oven light on to keep the temperature slightly elevated. You can also use hot water bottles or ice cold water bottles under the trays in an ice chest to raise or lower the temperature as needed.)
- Check the koji temperature every few hours to make sure it is staying in the 80-95ºF (27-35ºC) range. If the temperature gets too high for too long (over 104ºF (40ºC), unwanted bacteria can grow in the koji and spoil it. Each time you check on the koji, stir it, breaking up clumps as needed, and spread it out and add the furrows back in before covering and incubating again.
After 2- 2.5 days
- Continue to monitor the koji for 2 to 2 and a half days. You’ll notice that a fuzzy, soft white mold will cover the koji.
- It’s OK for some areas to begin to turn yellow or even a light yellow-green color. The yellowish green color is the formation of new koji spores. (Discard any koji that has grown black, or dark green mold. You also want to avoid any koji with shiny or sticky spots.)
Prepare the brine solution
- In a large glass container (around 2 gallons), mix together 1 gallon of filtered or spring water with 3.5 cups of sea salt. Stir until the salt has fully dissolved.
Prepare the moromi
- The moromi is the mixture of the koji and brine solution. Stir the koji into the brine solution and cover the mixture with a tight fitting lid. Label it with the date.
- Keep the moromi in a warm spot to continue to ferment. Stir the mixture daily for a week or so. After than, keep it in a warm spot (ideally around 77ºF (25ºC)), stirring it at least once a week for around 6 months.
- After around 6 months, you’ll notice that the color of the moromi will have darkened into a deep rust brown color. It may be either have separated into a liquid and solids (like mine) or be more or a homogenous thicker mixture.
Straining the moromi
- After 6-12 months fermentation, you’ll want to strain the moromi to obtain your homemade shoyu. The easiest way is probably to pour it into a cloth-lined strainer and pour some of the mixture into the strainer. You can then twist the cloth to press the filtered liquid through the cloth into a bottle.
- After around 9 months, around 3 months ago, I strained mine and it was a light, rust-colored liquid that tasted and smelled like soy sauce, but was much lighter in color.
- I was making homemade tamari at the same time (I’ll share that process soon- or as soon as I’m happy with the result), and this shows the 2 bottles I strained out 3 months ago. (I left the rest in the jar to continue fermentation there with the soybean and wheat mixture.)
Obtaining a dark-colored soy sauce
- One thing I had learned from my first failed attempts at making soy sauce was that one of the things that helped achieve a dark-colored soy sauce with complex flavors was to allow the sauce to ferment in the hot sun. So, I placed both bottles (of soy sauce and tamari) out in the hot sun from the end of June until the end of September. I was happy to see that both sauces had darkened with time out in the sun.
- You’ll notice that after 3 months outside in my sunny terrace, not only did they darken, but they also separated slightly leaving a bit of soy residue floating on top of the bottles. I strained the mixtures to obtain my sauces.
- I filtered the soy sauce again through a cloth to remove any soybean residue. The resulting liquid was a wonderfully dark colored shoyu with wonderful flavor.
Notes
What to do with the leftover soybean mash
While some people discard the soybean mash leftover after having strained out the soy sauce, others, like me, use it as they would miso in recipes.
Miso paste can be stirred into other sauces or mayonnaise to add a bit of saltiness and umami. It can be stirred into hot water, especially that boiled with seaweed varieties like kombu and wakame, to make a miso soup. The paste can also be added to stir fries.
Troubleshooting the soy sauce making process
My moromi is forming a mold on top
As a bit of an experiment, I had a separate jar of moromi fermenting that I left undisturbed. If you don’t stir the mixture very often, mold can form on top. After a bit of research, most soy sauce fermenters believed that it is OK to remove the top layer of mold and continue to ferment the sauce below.
In this case, the mold forming had the same colors and scent as the soy koji that I had made in the beginning, so I scraped peeled off the mold (it had a similar texture and held together as the koji had), continued to ferment the soy sauce, stirring occasionally. The resulting sauce didn’t appear any different than the other batch.
Use common sense here. If your moromi forms an unusual mold with a dark color or foul odor, while it may break your heart, you may be best to throw it away.
My moromi is forming a slimy layer
After having scraped off the moldy layer of my experimental batch of homemade soy sauce, I once again left it undisturbed. This time it didn’t form a mold, but instead formed a bit of a slimy layer on top. The top layer didn’t smell unpleasant, but I wasn’t sure I wanted to mix it in with the rest of the batch either.
My best guess is that this is some type of yeast that is forming on top. It gives off a yeast-y beer-like scent. Even though it wasn’t offensive, I scraped off most of the layer and mixed everything together again.
My soy sauce is too light in color
If I had only followed the instructions that came with my shoyu starter, I would have ended up with a dark amber colored soy sauce. In fact, most of my large batch still looks like the bottle above. (I took this picture this week of a bottle that I just strained.)
So, how did I end up getting such a beautifully dark soy sauce as shown in the first picture?
Well, two things help darken the soy sauce.
First, just filtering out any residual soybean paste will leave behind a darker color. After a couple of days, the soybean paste settled to the bottom, making the soy sauce look darker in color. To get it looking even darker, I filtered it through a tightly woven cotton cloth. You can see the huge difference in color already! It takes a bit of patience, but it’s worth the effort.
Second, it appears that one of the secrets to dark soy sauce is the same as the secret to dark skin in the summer… the sun!
The instructions that came with my starter never said anything about exposing the sauce to the sun, but through my earlier experimentation with making soy sauce using wild fungus, I learned that the sun may be your best friend when trying to make a dark, rich homemade soy sauce!
I read several accounts of people remembering their family members making soy sauce in Asia. They talked about the importance of using the sun, even to help prepare the brine for the koji. These people made the salt water ahead of time and allowed it to steep for several days in the sun before adding in the koji. They then proceeded to add the koji and allowed the mixture to ferment in the hot sun!
While I didn’t experiment with doing the whole fermenting process in the sun, I was a bit disappointed with the color of my homemade soy sauce, so I decided to experiment with leaving that outside in my terrace. I wasn’t sure if I’d be hurting the soy sauce, so I only strained out a small bottle and left it in a sunny part of my terrace for several weeks. (Looking at the dates on my photos, it appears that I actually left it there for almost 2 months.)
When it was time to take a look at it again, I was really happy to see how dark it had gotten. So, I’m now sunning out another bottle of soy and am tempted to bring out the whole unstrained batch!
Should you pasteurize your soy sauce?
It is said that pasteurization of the soy sauce will help extend its shelf life, and the cooking of the sauce helps to enhace its flavor and aroma. The idea is that you are killing off the bacteria in the sauce, and also beginning a Maillard reaction to deepen the flavor.
While that seems to be the general consensus, I’m not 100% sure if either of those statements is completely true. I’ve seen home brewers say that they like to leave half of their soy sauce unpasteurized because they think unpasteurized soy sauce has a more complex flavor profile. They pasteurize in the hopes of having their soy sauce last longer.
In a similar bit of skepticism, I really have to wonder if killing off the bacteria in the sauce will really extend its shelf life. When you make something like a homemade sauerkraut, some people say that the beneficial lactic acid bacteria that form also help preserve it. In fact, Leucidal, a natural preservative that I introduced when I shared how to make a lotion, uses Leuconostoc kimchii, a lactic acid bacteria formed when fermenting radishes, to restrict the growth of other microorganisms.
So, in the end, I’d say that experimenting and pasteurizing a small part of your batch is probably the best idea. That way you can decide if you prefer the flavor and aroma of unpasteurized soy sauce or not. You can also judge how long your sauce tastes best, and if you think that the pasteurized sauce lasts longer or not. I haven’t had mine for long enough to give you my opinion just yet…
I’ll try to update this post as I experiment with pasteurizing part of my batch.
How do you pasteurize soy sauce?
Cook the soy sauce at 160ºF (70ºC) for at least 30 minutes.
Does Soy Sauce Expire?
It takes between 6 months and a year to even be able to make a decent soy sauce. After that, it is usually said that soy sauce will last for around 3 years as long as you have it in sealed containers. It’s not necessarily that the soy sauce will “go bad” after that, but the quality of the sauce may deteriorate with time.
Here, again, I can’t speak from experience yet, and also have read accounts from home brewers who have said that their soy sauce has improved with time. Perhaps, here, the answer is it really depends on the batch, the method used for making the soy sauce, and your expectations of what makes a good soy sauce. Soy sauce may be like a good wine that improves with time- to a point! After a certain amount of time, some wines will begin to taste like vinegar. They aren’t toxic to drink, but they aren’t pleasant anymore either.
I’ll be keeping an eye on my own soy sauce, and will let you know my thoughts in a couple of years. Meanwhile, I’d love to hear from those of you with experience making your own soy sauce. 😉
Slava
Hello, Tracy! Recently, I made this sauce and I love it! It was so tasty. I used it for my braised mushrooms recipe-https://myediblefood.com/slow-cooker-braised-mushrooms-recipe/
Thank you very much for sharing it!
Tracy Ariza
Hi Slava,
I’m so happy it worked for you and you like it.
Calvin
I’m just wondering how much Koji rice I should use instead of koji starter for making soy sauce??
Tracy Ariza, DDS
Hi Calvin,
I’m not really sure as I haven’t tried with the koji rice itself. You’d have to do some experimentation and see how it turns out.
Jesse
Thank you so much for your hard work. Your first attempt seemed very much like mine.
I’ve been reading other sources for homemade soy sauce and the ratios are all quite a bit different. Yours was almost double the amount of soy and wheat to water. Do you have any thoughts on that?
Tracy Ariza
Hi Jesse,
I don’t know what to tell you about that. This time I followed the instructions that came with the particular culture I bought. After too many failed attempts, I wanted to do something tried and true. (That said, I also followed their instructions for gluten-free tamari-twice- and didn’t like the result either time. I’m not sure if it’s from the lack of the wheat or because it used a different culture.)
I really like the resulting soy sauce. It’s very good. I do tend to add some water when cooking.
In the end, I’d rather have a more concentrated sauce anyway. It takes up less space and you can always add water when using it if you want it less strong. 😉
Anirud
Hi, recently I’ve tried making soy sauce and it’s been a week since I started brining and it tastes very sour, almost like a lactic acid ferment. Is there a way to save it or do I have to start over
Tracy Ariza
Hi Anirud,
That’s really strange. I don’t think mine tasted sour even at the beginning.
Did you use a particular culture for making the koji?
I probably wouldn’t toss what you have (just in case). With time, it may change and get better.
You could consider trying starting out another batch to compare, though, and also to have a backup.
I’m guessing that the culture used could also make a huge difference.
Brytanny Howrd
Hello!!
Thank you so much for going through the trouble of making this sauce and sharing it everyone!!
I wanted to ask if you have the Tamari recipe ready to go yet? (I didn’t see it on the site) and second, my husband has a gluten allergy so I wanted to make some wheat free soy sauce. I cannot seem to find anything on the web on how to do this. But I have purchased gluten free soy sauce from the store, so I think it can be done but I don’t know where to even begin.
Thank you so much!!!!
Tracy Ariza
Hi Brytanny,
While I did make Tamari, I wasn’t happy with it- which is why I didn’t post it.
The problem with these sorts of experiments is that they take many months to complete, so I’m not sure when I’ll get something successful enough to post. Even this soy sauce post has been years in the making! I finally made a sauce I was really happy with.
I really want to try with this culture, but without wheat.
HappyCooking
Hi Brytanny,
I am about to start making soy sauce at home so I’ve been doing a lot of research about it recently. Yesterday I bumped into an article that shares Vietnamese tradition of making soy sauce using the roasted ground rice instead of the wheat berries. They roast the rice fisrt and then grind it (just like you do with the wheat berries) . Because the article is not in English so I do not include the link here.
I hope this is helpful if you want to make wheat free soy sauce.
The amount they use is 150g roasted ground rice for 1kg of soybeans; they don’t use koji starter. The prepared steps are the same and they leave the jar outside in the sun for all summer.
Tracy Ariza
Hello!
Thank you for the tip!
Yes, I was considering doing that. I think I tried using rice flour with my first batch, but that was the one that tried using wild molds (kind of like them, I guess)- and, well, wasn’t really the best outcome. They probably have different wild strains of yeasts and molds, though. (I’d actually love to see the link anyway, if you see this and can find it. It may have been one of the ones I read a long time ago when I started making this.)
I’d really like to try with the strain (of koji starter) that worked so well for the shoyu, but to try with a flour without gluten.
Darlene
I have high blood pressure so I’m considering making my own sauces. Can soy sauce be made without salt?
Thanks.
Darlene
Tracy Ariza
Hi Darlene,
I doubt you can make soy sauce without salt. It helps preserve it and keep out the bad microbes. Plus it gives soy sauce its characteristic flavor.
Nolan
Yes. Add lactic acid and the requisite yeast (S. Rouxii) as well and stir at least once a day for the first month to aerate the moromi.I’ve never heard of soy sauce being an aerobic process. The lactic acid replaces the halotolerant lactofermentaion that typically takes place in soy sauce that also allows the requisite yeasts and bacteria to develop. Every Asian culture makes soy sauce different ways, but the Koreans typically depend on B. Subtillis to create a dank, musty strong smell – it’s the same bacteria that creates natto – that many people are not accustomed to
Tracy Ariza
Hi Nolan,
Thank you so much for your very interesting and informative reply!
Cooking 4 U
So I was watching a cooking show that recorded at a monastery. There they had homemade seven year old soy sauce. Could your process be used for something like that?
Tracy Ariza
Hello,
I would think so. You would just let it ferment for the full seven years. 😉
Nicholas
Thank you so much for this recipe! So much effort and years went into this, this will save a lot of time for me as I learn to do the same. How did the sun affect the flavor? I’m not really too interested in the color differences, I’m fine with a beige soy sauce, but you say “richer”. Is there a more descriptive difference? I might try both methods and taste it though.
Tracy Ariza
Hi Nicolas,
To be honest, I don’t really notice much of a difference in taste between those that were in the sun and those that weren’t. It mostly only changed in color, I think.
If you do give it a try, I’d love to hear how it goes and your thoughts on getting it to look/taste “right.”
My focus now is to try getting a gluten-free version that tastes like soy sauce. 😉
Good luck with it!
Fernando Javier
Hola Tracy,
crees que se podría sustituir el trigo para realizar la salsa de soja por espelta?.
Además tengo malta de diferentes tipos para hacer cerveza casera, sabes algo de que tal resultado da si se añade en pequeñas cantidades?.
Otra opción sería remojar la soja y dejarla germinar un poco antes de cocerla al vapor, pero no he encontrado nada al respecto, y me extraña.
Un saludo
Fernando Javier
(Lleida)
Tracy Ariza
Hola Fernando Javier,
La verdad es que no lo sé seguro.
Como he escrito en el post, probé de hacerlo sin harina de trigo para hacer tamari.
Lo que confunde todo es que usé otro cultivo con ese- ya que el sitio que vendía los cultivos, tenían uno para shoyu y otro para tamari.
No me ha gustado tanto el sabor del tamari, pero al final, al haber usado otro cultivo, no sé si es por culpa del cultivo o si es por no haber usado el trigo.
Lo malo es que lo probé de hacer varias veces ya. Tarda tanto el proceso, que tardas en volver a probar. Con el primer intento, pensaba que había hecho algo mal, pero me salió igual años después así que me imagino quer lo hice bien y es así y ya está.
Tengo pensado ahora esta primavera hacer una prueba con el cultivo de shoyu pero sin trigo, pero como no lo he hecho todavía, no te puedo decir seguro lo que sale si usas espelta o otro tipo de harina. Me imagino que con espelta no habría problema ya que es un tipo de trigo antiguo y debería reaccionar de manera parecida.
Sin algo así, sin embargo, no tengo ni idea. Lo malo es que tardaré a tener la respuesta ya que el proceso es muy lento. 😉
Lo de germinarlo- es buena idea. No sé como funcionaría.
Si experimentas con ello, me encantaría saber cómo va. Puede ayudar a otra gente.
Un saludo desde Alicante. 🙂
Brenda
You mentioned that the soy sauce could degrade after 2 or 3 years. But in actuality, the soy sauce improves in flavor as it ages, just as miso does – especially the dark, salty misos that are made to last for years. The flavors become more earthy, more complex, more umami. I have made soy sauce both ways (by capturing wild yeasts from the air, and by adding the spore to make koji). Both were very successful, and resulted in delicious soy sauce and miso.
For folks who want a soy-free sauce/miso, other beans can be used, including peanuts. Just use them in exactly the same way as they soybeans. Of course, the flavors will be different, but that is to be expected when using other beans/peas. For folks who want a wheat-free version, use rice koji to inoculate the beans, or inoculate the beans only with the koji spore, and proceed with the recipe from there.
Tracy Ariza
Hi Brenda,
I assumed that myself, and have heard of many who say the same. Others, though, insist that it can degrade with time. As I’ve only had mine for 2 years (and, yes, I quite like it now 😉 ), I just threw that out there just in case.
Interesting about the peanuts!
Yes, I want to try again without wheat- this time using the same exact culture. I used one meant specifically for making wheat-free tamari, but I didn’t like it either time. (I wasted a year or two on one batch a long time ago, and then repeated again at the same time as I made the shoyu just in case I had done something wrong the first time. Both times it came out exactly the same. 🙁 )