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Miso and soy sauce are both made with soybeans, are fermented with koji and lactic acid bacteria and usually take months to years before they are ready for consumption. So what are the differences between miso and soya sauce?
| Miso | Soy sauce |
| Paste | Liquid |
| Most commonly Used to make soup | Most commonly used as a condiment |
| Made with rice or barley | Made with wheat |
| Fermented in an anaerobic environment | Fermented in an aerobic environment |
| Is not usually pasteurized | Usually pasteurized |
| The whole bean is consumed | Only the liquid component is consumed |
| Aged as little as 30 days | Must be aged at least 6 months to a year |
| Koji mold arrested before it sporulates | Koji mold grown until is sporulates |
| Must be made naturally | Can be made through chemical processes |
| Nutrient profile | Nutrient profile |
| Partial substrate pre-fermentation | Total substrate pre-fermentation |
Product Consistency
Miso is a fermented soybean paste which is most famous for flavoring Miso soup. It is thick and can be used to thicken sauces while adding umami flavor.
Soy sauce is a liquid which is used as a condiment. It is usually added to food to adjust the flavor to suit the diner. It also has umami flavor but also adds a salty flavor to the food.
Ingredients:
Miso mainly contains soybeans, rice and/or barley and salt. Some types of miso only contain soybeans while others include seaweed in the ingredient listing. Miso has also been made using other beans besides soybeans but few are made commercially. Miso Master makes a chickpea and rice miso which has less salt and more rice koji then traditional miso.
The ingredients of soy sauce vary depending on the location, ethnicity, company values and type of soy sauce being made.
The first and cheapest method of producing soy sauce uses a chemical process to break down the proteins and starches in the soybeans. The ingredient listing for this type of soy sauce is long and reads like a chemical supply company catalog (not a recommended food item).
Soy sauce is traditionally made with soybeans, wheat, water and salt but each ethnic group has variations.
- Chinese soy sauce is traditionally made with mostly soybeans but may use wheat as a culturing medium to grow the koji prior to the initial fermentation of the soybeans.
- Japanese soy sauce is made with roughly half soybeans to wheat.
- Korean soy sauce was originally a byproduct of fermented soybean paste a product which closely resembles miso from Japanese culture. The liquid from a mixture of soybeans, salt and water.
- Other traditions include using rice rather than wheat, several different types of sugar are also used including molasses or palm sugar after the fermentation process is complete.
Fermentation methods
Both Miso and Soy sauce start with an aerobic fermentation step. This step is where the mold Aspergillus oryzae is grown to produce enzymes which break down the sugars in the fermentation making them easily available to lactic acid bacteria and yeasts.
Once the miso koji is complete it is mixed with the soybean and rice mixture and packed into fermentation containers and sealed to prevent oxygen exchange, making it an anaerobic fermentation. Miso under goes fermentation from lactic acid bacteria which convert the sugars in the soybean mash into lactic acid, CO2 and ethanol. The yeast Zygosaccharomyces rouxii is also present and converts the sugars into CO2 and ethanol.
Due to the thick nature of the soybean mash this process is slow and can take years for completion. This is why white miso is sweater but less complex then red miso.
The process for the second fermentation of soy sauce includes the addition of water and salt. The mixture is poured into fermenting containers and stirred daily making it an aerobic fermentation. The yeast Zygosaccharomyces rouxii and acidic acid bacteria convert the sugars in the soybean mixture into acidic acid, ethanol and CO2.
As the mixture is still fairly thick it requires daily stirring for the first stage of fermentation. As the sugars are consumed it is stirred less often but still requires attention to prevent mold growth and even distribution of available sugars.
Pasteurization
Pasteurization is the destruction of active microorganisms through the use of heat. It is used to preserve foods, stabilize flavors and prevent further fermentation.
Miso usually does not undergo pasteurization. If it is kept in an anaerobic environment and will continue to ferment and develop a richer more complex flavor. If used without cooking it will have live probiotic bacteria in it. If used in cooking like in miso soup the probiotic bacteria are mostly destroyed.
Soy sauce is usually pasteurized after it has been pressed from the soybean mash. There are several reasons why this is done including:
- Halting the fermentation to produce a specific flavor profile
- Allowing it to be shelf stable (not requiring refrigeration)
- Allowing additional flavoring and thickeners such as palm sugar and tapioca flour
Not all soy sauce is pasteurized. Some brands offer an unpasteurized version of their soy sauce as well as several artisanal soy sauce makers in japan produce exclusively unpasteurized soy sauce. It is expensive and has a different flavor than the usual store bought version.
How much of the soybean consumed
When making miso the soybeans are mashed up and packed into aging containers. Once the fermentation is complete there is no waste product left behind as the miso is simply transferred into smaller containers for sale.
When making soy sauce the fermenting soybean mash is pressed once the fermentation period is complete. This removes the solids from the mash and producing the thin liquid which we know as soy sauce. The remaining solids are made up of unfermented starches and fiber which is high in protein. This byproduct is usually sold as high value livestock feed.
Nutrient Profile
Although Miso and Soy sauce are made from the same basic ingredients the nutritional profiles are different. Both have a high amount of salt with soy sauce having a higher amount per hundred grams, miso has more fiber then soy sauce, over twice the amount of calcium whereas soy sauce has more niacin then miso.
For specific and in depth information refer to the following table.
| Nutrients | Miso | Soy Sauce | ||||
| Amount | Unit | DV | Amount | Unit | DV | |
| Alanine | 0.5 | G | 0.536 | G | ||
| Arginine | 0.784 | G | 0.405 | G | ||
| Ash | 12.81 | G | 17.82 | G | ||
| Aspartic acid | 1.171 | G | 0.882 | G | ||
| Calcium, Ca | 57 | MG | 4% | 20 | MG | 2% |
| Calories | 198 | KCAL | 60 | KCAL | ||
| Carbohydrate | 25.37 | G | 9% | 5.57 | G | 2% |
| Carotene, beta | 52 | UG | 0 | UG | ||
| Choline | 72.2 | MG | 38.4 | MG | ||
| Copper, Cu | 0.42 | MG | 47% | 0.135 | MG | 15% |
| Cystine | 0 | G | 0.107 | G | ||
| Docosanoic acid | 0.05 | G | 0 | G | ||
| Eicosenoic acid | 0.025 | G | 0 | G | ||
| Fat | 6.01 | G | 8% | 0.1 | G | 0% |
| Fiber | 5.4 | G | 19% | 0.8 | G | 3% |
| Folate | 19 | UG | 18 | UG | ||
| Folate, DFE | 19 | UG | 5% | 18 | UG | 4% |
| Folate, food | 19 | UG | 18 | UG | ||
| Fructose | 6 | G | 0 | G | ||
| Glutamic acid | 1.915 | G | 2.411 | G | ||
| Glycine | 0.447 | G | 0.435 | G | ||
| Heptadecanoic acid | 0.01 | G | 0.008 | G | ||
| Heptadecenoic acid | 0.03 | G | 0 | G | ||
| Hexadecanoic acid | 0.75 | G | 0 | G | ||
| Histidine | 0.243 | G | 35% | 0.215 | G | 31% |
| Iron, Fe | 2.49 | MG | 14% | 2.38 | MG | 13% |
| Isoleucine | 0.508 | G | 36% | 0.487 | G | 35% |
| Leucine | 0.82 | G | 30% | 0.735 | G | 27% |
| Lysine | 0.478 | G | 23% | 0.731 | G | 35% |
| Magnesium, Mg | 48 | MG | 12% | 40 | MG | 10% |
| Maltose | 0.2 | G | 0.2 | G | ||
| Manganese, Mn | 0.859 | MG | 37% | 0.499 | MG | 22% |
| Methionine | 0.129 | G | 0.167 | G | ||
| Methionine + Cysteine | 0.129 | G | 12% | 0.167 | G | 16% |
| Monounsaturated fatty acids | 1.118 | G | 0.017 | G | ||
| Niacin | 0.906 | MG | 6% | 3.951 | MG | 25% |
| Octadecadienoic acid | 2.479 | G | 0.039 | G | ||
| Octadecanoic acid | 0.2 | G | 0.003 | G | ||
| Octadecatrienoic acid | 0.405 | G | 0.005 | G | ||
| Octadecenoic acid | 1.043 | G | 0.017 | G | ||
| Pantothenic acid | 0.337 | MG | 7% | 0.376 | MG | 8% |
| Pentadecenoic acid | 0.02 | G | 0 | G | ||
| Phenylalanine | 0.486 | G | 0.534 | G | ||
| Phenylalanine + Tyrosine | 0.838 | G | 48% | 0.876 | G | 50% |
| Phosphorus, P | 159 | MG | 23% | 130 | MG | 19% |
| Polyunsaturated fatty acids | 2.884 | G | 0.044 | G | ||
| Potassium, K | 210 | MG | 4% | 212 | MG | 5% |
| Proline | 0.619 | G | 0.806 | G | ||
| Protein | 12.79 | G | 26% | 10.51 | G | 21% |
| Riboflavin | 0.233 | MG | 18% | 0.152 | MG | 12% |
| Saturated fatty acids | 1.025 | G | 5% | 0.011 | G | 0% |
| Selenium, Se | 7 | UG | 13% | 0.8 | UG | 1% |
| Serine | 0.601 | G | 0.483 | G | ||
| Sodium, Na | 3728 | MG | 162% | 5586 | MG | 243% |
| Sugars | 6.2 | G | 1.7 | G | ||
| Tetradecanoic acid | 0.015 | G | 0.015 | G | ||
| Thiamin | 0.098 | MG | 8% | 0.059 | MG | 5% |
| Threonine | 0.479 | G | 46% | 0.407 | G | 39% |
| Tocopherol, alpha | 0.01 | MG | 0 | MG | ||
| Tryptophan | 0.155 | G | 55% | 0.181 | G | 65% |
| Tyrosine | 0.352 | G | 0.342 | G | ||
| Valine | 0.547 | G | 30% | 0.524 | G | 29% |
| Vitamin A | 87 | IU | 2% | 0 | IU | 0% |
| Vitamin A, RAE | 4 | UG | 0 | UG | ||
| Vitamin B12 | 0.08 | UG | 3% | 0 | UG | 0% |
| Vitamin B6 | 0.199 | MG | 15% | 0.2 | MG | 15% |
| Vitamin E | 0.01 | MG | 0% | 0 | MG | 0% |
| Vitamin K | 29.3 | UG | 24% | 0 | UG | 0% |
| Water | 43.02 | G | 66 | G | ||
| Zinc, Zn | 2.56 | MG | 23% | 0.43 | MG | 4% |
Aging time
Not all miso types are long aged. Miso can be aged for as little as 30 days for really sweat white miso. This type of miso is used for sweat sauces and dessert recipes.
The length of commercially prepared miso varies between six months to two years but usually red miso is aged a year before it is packaged and sold.
There are two methods used to make soy sauce. The chemical process which can take only a few days and the traditional method which takes at least six months.
Since the chemical process does not produce an acceptably fermented product and needs to be adjusted with unnatural flavor enhancers and coloring agents it will not be considered here.
Traditionally brewed soy sauce is a natural fermentation process which takes at least six months before an acceptable product is produced. Some artisanal soy sauce brewers will ferment their soy sauce for a year to two years and once it has been pressed it can be aged for long periods of time. As it ages it turns into a syrupy dark liquid reminiscent of balsamic vinegar.
Mold sporulation
Miso koji is made with the same mold as is used in soy sauce but the amount of time it is left to grow is different.
For miso the mold is used to produce enzymes which then act on the starches in the soybean mash and convert them into sugar. The koji which is produced in the first stages of miso production is used before the mold sporulates. Sporulation produces a green color over the substrate and in miso produces bitter flavors which are not wanted.
Soy sauce koji is fermented for a minimum of three days and is not finished until mold sporulation occurs. The soybean and wheat mixture has a green hue which indicated the mold has reached maturity. It is at this point that the koji mixture is moved to the second fermentation stage by adding water and salt which stops the mold fermentation and instigates the yeast and acidic acid fermentation.
Methods of production
The production of these two products is a commercial enterprise. It is done to make a product which is saleable and profitable. In order to do that there are several methods which different companies have used to produce both of these products.
Miso is still (thankfully) an all-natural process. The soybeans are usually non-GMO, although this is an important thing to check before you buy. The soybeans are fermented with the traditional bacterial, yeast and mold cultures and use the usual rice or barley.
Soy sauce is not so lucky. Chemical processes have been used to break down the starches in the soybeans quickly. This process skips the koji making step and in its place a bath in a strong hydrochloric acid solution is used to break down the starches. It is like bathing the soybeans in digestive acid. The resulting mash then ferments quickly and can be made in a few days.
This process does not produce a quality product and needs to be colored, and flavored to make it palatable. Some companies will mix naturally fermented soy sauce with soy sauce made with this process to improve sales and consumer acceptance.
As consumers are becoming more aware of the detrimental effects of chemical additives in their food naturally fermented soy sauce has become more popular even though these types are more expensive.
The traditional way of making soy sauce uses soybeans, wheat, water and salt which are fermented together for at least 6 months. The resulting mash is then pressed to extract the liquid which is then bottled and sold as soy sauce.
Koji Fermentation Methods
Although miso and soy sauce are started the same way with a koji fermentation step the methods are different.
Miso koji is made with rice or barley and in some cases soybeans. It is then used to stratify the starches in the main soybean mash. The starches in the mash are broken down by the enzymes which were produced in the koji fermentation stage and the few additional enzymes which are produced throughout the remainder of the fermentation process.
Soy sauce is made by mixing the koji mold with all of the soybeans and wheat mixture to produce the koji. It is then fermented until it sporulates. This produces a high amount of sugars which are used by the yeasts and acidic acid bacteria to further break down the soybeans and wheat.
