Miso is a fermented Japanese seasoning paste made from soybeans, salt, and koji mold — with rice or barley added in most styles. The koji breaks down the soybeans over weeks or years, producing a thick paste rich in umami, amino acids, and complex flavour. It is not a single product: white miso ferments for 4–8 weeks at 5–8% salt; hatcho miso ferments for 3+ years at 11% salt. The variation in fermentation time, grain base, and salt level accounts for the dramatic range across miso styles.

What does miso taste like?

Miso is umami-forward, salty, faintly sweet, and slightly funky — but those words do not capture how much the flavour varies by type. White (shiro) miso is mild, sweet, and almost buttery, with 5–8% salt. Red (aka) miso is bold, deeply savoury, and complex, with 11–13% salt. Saikyo miso tastes almost dessert-like — very sweet and barely salty. Hatcho miso is intense and almost crumbly, used in small amounts. The common thread is glutamate-driven umami, but the intensity and sweetness shift dramatically across the spectrum.

What is the difference between white and red miso?

White miso (shiro) ferments for 4–8 weeks with a high ratio of rice koji to soybeans, producing a pale, mildly sweet paste at 5–8% salt. Red miso (aka) ferments for 6–12 months or longer with more soybeans and less rice, producing a dark, boldly savoury paste at 11–13% salt. The colour difference is a direct result of fermentation time and the Maillard-type browning reactions that occur during ageing. Awase miso blends both for everyday versatility. For a full side-by-side breakdown, see the white miso vs red miso comparison.

Miso is nutrient-dense: it provides protein (9–14g per 100g), B vitamins, isoflavones from soybeans, and — in unpasteurised varieties — live lactobacillus cultures. The main nutritional caveat is sodium: one tablespoon (18g) of white miso contributes roughly 600–900mg of sodium, depending on the brand. For context, the daily recommended limit is 2300mg. Used as a seasoning rather than a main ingredient, miso adds significant flavour for a modest salt contribution. The meaningful health choice is preferring unpasteurised miso (sold refrigerated) over pasteurised shelf-stable versions for probiotic benefit.

Does miso have gluten?

It depends on the type. Rice miso and soybean miso (hatcho) are made with rice or pure soybeans, and are typically gluten-free — but check the label, as production lines may vary. Mugi miso is made with barley and is not gluten-free. Many mainstream miso brands now produce certified gluten-free versions of their rice or soybean miso. If gluten is a concern, look for labels specifically marked gluten-free, or choose hatcho miso (100% soybean, no grain koji) from a dedicated facility.

What is miso made from?

Most miso contains four ingredients: soybeans, koji (a mold, Aspergillus oryzae, grown on a grain), salt, and time. Rice miso uses rice koji; barley miso uses barley koji; hatcho uses only soybeans with no grain koji at all. The koji produces enzymes that break down the soybeans' proteins and starches over the fermentation period, generating amino acids (umami), sugars (sweetness), and organic acids (complexity). A clean ingredient label showing only soybeans, rice (or barley), salt, and possibly water is the sign of quality miso. Avoid products with MSG, alcohol preservatives, or artificial sweeteners.

Can I use miso instead of soy sauce?

In some cases, yes — but they behave differently. Soy sauce is a liquid; miso is a paste. Miso must be dissolved before use, adds body and thickness, and has a more complex, less clean flavour. A rough conversion: 1 tablespoon of miso can replace about 1/2 teaspoon of salt or approximately 1 tablespoon of soy sauce in terms of saltiness, but the miso also adds fermented depth and texture that soy sauce does not. Miso works better as a soy sauce replacement in marinades, dressings, braises, and sauces than in applications that need a clean, thin liquid seasoning (like finishing a delicate clear broth).

How long does miso last?

Miso is one of the most shelf-stable ingredients in any kitchen. Refrigerated after opening, white miso keeps for 2–3 months at its best quality; red and darker misos keep for 6–12 months or longer because their higher salt content slows degradation. Miso does not become unsafe in a food-safety sense — the 10–13% salt content prevents pathogen growth — but the colour darkens gradually and the aroma flattens over time. To maximise storage life: refrigerate at all times, press plastic wrap directly onto the miso surface to prevent oxidation, and use a clean dry spoon to avoid introducing moisture.

What Is Miso? Types, Flavours, and How to Buy

Start here — what do you need?

I need to buy my first miso → buying guide section below
I want to understand the different miso types → types section below
I want to cook with miso (ratios, techniques) → How to Use Miso
I'm confused about miso vs soy sauce → comparison section below
White vs red — which is better? → White Miso vs Red Miso

What Miso Actually Is

Miso is a fermented paste made from soybeans, salt, and koji — the mold Aspergillus oryzae grown on a grain substrate (usually rice or barley). The koji produces protease and amylase enzymes that break down the soybeans' proteins and starches during fermentation, generating amino acids responsible for umami, sugars that create sweetness, and organic acids that add complexity.

Fermentation time and the ratio of koji to soybeans are the two variables that determine everything about the final paste's flavour, colour, and salt level. A white miso ferments for 4–8 weeks with a high rice-koji ratio — the result is pale, sweet, and mild at 5–8% salt. A hatcho miso ferments for 3+ years with no grain koji at all — the result is nearly black, intensely savoury, and earthy at 11% salt.

The koji process is shared with sake, soy sauce, and shio koji — all use Aspergillus oryzae as a fermentation catalyst. What makes miso distinct is the paste form and the extended contact time between koji and soybeans, which produces a much more complex flavour profile than a short-fermented condiment.

A clean miso ingredient label should show only: soybeans, rice or barley (or neither, for hatcho), salt, and possibly water. Avoid products with MSG, alcohol preservatives, or artificial sweeteners — those are production shortcuts that flatten the fermentation character.

The Five Main Miso Types — and What Each Is For

The practical difference between miso types is not prestige or tradition — it is function. Each type ferments differently and behaves differently in food. Here are the five types worth knowing, with specific fermentation data and best-use guidance:

Shiro (White) Miso — 4–8 weeks, 5–8% salt

The mildest and most approachable miso. A high ratio of rice koji to soybeans and a short fermentation of 4–8 weeks produce a pale beige paste that is gentle, slightly sweet, and only faintly funky. Salt content is the lowest of all miso styles at 5–8%.

Best for: miso soup with delicate ingredients (tofu, wakame), salad dressings, marinades for white fish and chicken, miso butter, light glazes, and any application where you want umami body without dominant fermented assertiveness.

Recommended brand: Hikari Organic White Miso (widely available in the US and UK), or Miso Master Organic White Miso.

Shop Hikari Organic White Miso on Amazon →

Aka (Red) Miso — 6–12 months, 11–13% salt

Red miso ferments for 6–12 months or longer with a higher soybean ratio and less rice koji. The extended fermentation drives Maillard browning reactions that turn the paste dark reddish-brown and develop a deeply savoury, complex, slightly earthy flavour. Salt content is 11–13% — noticeably more intense than white miso.

Best for: hearty miso soup, ramen tare, braises and stews, bold glazes, red meat marinades, and any dish that can absorb and benefit from an assertive fermented backbone. Use in smaller quantities than white miso — start at 2 teaspoons per 240ml of broth rather than the standard 1 tablespoon.

Awase (Blended) Miso — medium depth, moderate salt

Awase miso is a commercial blend of white and red miso, typically in a 60/40 or 70/30 ratio. The blending produces a versatile, well-rounded paste that sits in the middle of the flavour spectrum: more depth than white, less assertiveness than red.

Best for: everyday miso soup and general cooking when you keep only one miso in the fridge. This is the default choice for most Japanese households. If you are buying a first tub and want maximum versatility, awase is the strongest starting point.

Saikyo (Kyoto Sweet White) Miso — 1–2 weeks, 5–6% salt

Saikyo miso is a Kyoto regional specialty — the sweetest, most delicate miso style. A very short fermentation of 1–2 weeks and an extremely high rice koji ratio produce a pale, almost white paste with high residual sugar content and the lowest salt level of any miso style at 5–6%.

Best for: the Nobu-style black cod and salmon marinades that made saikyo-yaki famous; nasu dengaku (miso-glazed eggplant); and dessert applications where miso's umami is used as a savoury counterpoint to sweetness. Not suited to hearty soups or braises — the flavour disappears.

Hatcho Miso — 3+ years, 11% salt

Hatcho miso is made in Okazaki (Nagoya region), using 100% soybeans with no grain koji — just soybeans, salt, water, and years. The result is an almost black, very firm, nearly crumbly paste with intense savoury depth and a distinctive earthy bitterness. Fermented for a minimum of 3 years (some versions 5+ years), it is the most aged and most concentrated miso style.

Best for: miso nikomi udon, Nagoya-style dishes, and blending with lighter miso to add depth. Use in small amounts — 1–2 teaspoons in a pot of soup rather than the full tablespoon a white miso requires. Too intense for dressings or delicate applications.

Which Miso to Buy First

The buying decision comes down to your cooking range and how many misos you are willing to keep in the fridge:

One tub only: buy awase. It covers everyday soup, basic dressings, simple marinades, and general seasoning without pulling the flavour too sweet or too bold.
Two tubs: buy white (shiro) for dressings, light dishes, and delicate proteins; buy red (aka) for hearty soups, braises, and ramen. Together they cover 95% of home cooking needs.
Specific use — black cod or glazed eggplant: buy saikyo. Nothing else produces the same caramelised, sweet-savoury crust.
Specific use — deep Nagoya-style cooking: buy hatcho to blend, not to use alone.

For a head-to-head comparison of white and red with more buying detail, see White Miso vs Red Miso.

What Miso Tastes Like

Across all types, miso is umami-forward, salty, and complex. But the flavour range is wider than most condiments:

White miso: mild, slightly sweet, almost buttery, faintly earthy. Easy to eat straight from a spoon.
Awase: balanced savoury depth, moderate saltiness, recognisably fermented but not overpowering.
Red miso: bold, assertive, intensely savoury with a slight bitterness and a longer, drier finish.
Saikyo: sweet, delicate, almost dessert-like — the fermented character is subtle and the sweetness leads.
Hatcho: intensely savoury, earthy, slightly bitter, with a dense, crumbly texture and a long finish. Used in small amounts as a flavour anchor.

The common thread across all types is glutamate — the amino acid behind umami. Miso is one of the richest natural sources of glutamate, which is why it makes soups, sauces, and marinades taste more complete even in small quantities.

Miso vs Soy Sauce — the Key Differences

Both miso and soy sauce are fermented soybean products built with koji, but they are not interchangeable:

Property	Miso	Soy sauce
Form	Thick paste	Thin liquid
Salt	5–13% depending on type	~16–18%
Use method	Dissolve or spread	Pour or brush
Flavour	Umami + body + complexity	Umami + clean saltiness
Texture contribution	Adds body and thickness	Adds none
Best role	Seasoning paste, marinade base	Seasoning liquid, finishing

Miso can replace soy sauce in marinades, dressings, and braises where you want body and fermented depth. It should not replace soy sauce in applications that need a clean, thin liquid (clear broths, dipping sauces for sushi). For a full side-by-side comparison of the two, see Miso vs Soy Sauce. For a longer look at the soy sauce family, see What Is Soy Sauce.

Nutritional Profile

Per tablespoon (18g) of white miso:

Sodium: approximately 600–900mg (high — this is the primary nutritional consideration)
Protein: 2–3g — miso is a meaningful protein source when used as a seasoning across multiple dishes
Carbohydrates: 2–4g in white miso (higher rice koji ratio); 1–2g in red miso
Probiotics: present in unpasteurised miso (sold refrigerated); destroyed in pasteurised versions regardless of temperature
Isoflavones: from soybeans — a class of phytoestrogens associated with reduced risk of certain cancers in population studies
B vitamins: including B12 in fermented versions — relevant for plant-based diets

The meaningful nutritional choice is unpasteurised miso (refrigerated section, usually labelled “contains live cultures” or without added preservatives) over pasteurised shelf-stable versions. Probiotic benefit requires live organisms; no boiling required — add miso to soup at 60–70°C, off heat.

How to Store Miso

Refrigerate after opening. Store at 1–5°C. The cold slows enzymatic darkening and preserves aromatic complexity.
Press plastic wrap onto the surface. Miso oxidises where it contacts air, forming a dry, darkened crust. Direct-contact wrap eliminates this — push the wrap down until it touches the miso with no air pockets.
Use clean, dry utensils. Introducing water or food residue into the tub accelerates spoilage. Dedicate a small spoon to your miso container.
Shelf life: white miso, refrigerated, keeps at best quality for 2–3 months after opening. Red miso keeps for 6–12 months. Hatcho miso, in its dense crumbly form, is stable for 12+ months. Miso does not become unsafe — the salt prevents pathogens — but flavour flattens over time.

Frequently asked questions

What is miso?: Miso is a fermented Japanese seasoning paste made from soybeans, salt, and koji mold — with rice or barley added in most styles. The koji breaks down the soybeans over weeks or years, producing a thick paste rich in umami, amino acids, and complex flavour. It is not a single product: white miso ferments for 4–8 weeks at 5–8% salt; hatcho miso ferments for 3+ years at 11% salt. The variation in fermentation time, grain base, and salt level accounts for the dramatic range across miso styles.
What does miso taste like?: Miso is umami-forward, salty, faintly sweet, and slightly funky — but those words do not capture how much the flavour varies by type. White (shiro) miso is mild, sweet, and almost buttery, with 5–8% salt. Red (aka) miso is bold, deeply savoury, and complex, with 11–13% salt. Saikyo miso tastes almost dessert-like — very sweet and barely salty. Hatcho miso is intense and almost crumbly, used in small amounts. The common thread is glutamate-driven umami, but the intensity and sweetness shift dramatically across the spectrum.
What is the difference between white and red miso?: White miso (shiro) ferments for 4–8 weeks with a high ratio of rice koji to soybeans, producing a pale, mildly sweet paste at 5–8% salt. Red miso (aka) ferments for 6–12 months or longer with more soybeans and less rice, producing a dark, boldly savoury paste at 11–13% salt. The colour difference is a direct result of fermentation time and the Maillard-type browning reactions that occur during ageing. Awase miso blends both for everyday versatility. For a full side-by-side breakdown, see the white miso vs red miso comparison.
Is miso healthy?: Miso is nutrient-dense: it provides protein (9–14g per 100g), B vitamins, isoflavones from soybeans, and — in unpasteurised varieties — live lactobacillus cultures. The main nutritional caveat is sodium: one tablespoon (18g) of white miso contributes roughly 600–900mg of sodium, depending on the brand. For context, the daily recommended limit is 2300mg. Used as a seasoning rather than a main ingredient, miso adds significant flavour for a modest salt contribution. The meaningful health choice is preferring unpasteurised miso (sold refrigerated) over pasteurised shelf-stable versions for probiotic benefit.
Does miso have gluten?: It depends on the type. Rice miso and soybean miso (hatcho) are made with rice or pure soybeans, and are typically gluten-free — but check the label, as production lines may vary. Mugi miso is made with barley and is not gluten-free. Many mainstream miso brands now produce certified gluten-free versions of their rice or soybean miso. If gluten is a concern, look for labels specifically marked gluten-free, or choose hatcho miso (100% soybean, no grain koji) from a dedicated facility.
What is miso made from?: Most miso contains four ingredients: soybeans, koji (a mold, Aspergillus oryzae, grown on a grain), salt, and time. Rice miso uses rice koji; barley miso uses barley koji; hatcho uses only soybeans with no grain koji at all. The koji produces enzymes that break down the soybeans' proteins and starches over the fermentation period, generating amino acids (umami), sugars (sweetness), and organic acids (complexity). A clean ingredient label showing only soybeans, rice (or barley), salt, and possibly water is the sign of quality miso. Avoid products with MSG, alcohol preservatives, or artificial sweeteners.
Can I use miso instead of soy sauce?: In some cases, yes — but they behave differently. Soy sauce is a liquid; miso is a paste. Miso must be dissolved before use, adds body and thickness, and has a more complex, less clean flavour. A rough conversion: 1 tablespoon of miso can replace about 1/2 teaspoon of salt or approximately 1 tablespoon of soy sauce in terms of saltiness, but the miso also adds fermented depth and texture that soy sauce does not. Miso works better as a soy sauce replacement in marinades, dressings, braises, and sauces than in applications that need a clean, thin liquid seasoning (like finishing a delicate clear broth).
How long does miso last?: Miso is one of the most shelf-stable ingredients in any kitchen. Refrigerated after opening, white miso keeps for 2–3 months at its best quality; red and darker misos keep for 6–12 months or longer because their higher salt content slows degradation. Miso does not become unsafe in a food-safety sense — the 10–13% salt content prevents pathogen growth — but the colour darkens gradually and the aroma flattens over time. To maximise storage life: refrigerate at all times, press plastic wrap directly onto the miso surface to prevent oxidation, and use a clean dry spoon to avoid introducing moisture.

Where to go next

How to Use Miso — ratios, techniques, and every major application with exact quantities
White Miso vs Red Miso — side-by-side comparison for the buying decision
Miso Substitute — what to use when you are out of miso
What Is Koji — the mold that makes miso (and sake, and soy sauce) possible
What Is Shio Koji — a related koji condiment used as a salt substitute and marinade
What Is Dashi — the broth that miso soup is built on
What Is Soy Sauce — the other major fermented soybean condiment
Japanese Pantry — how miso fits into the broader Japanese ingredient system
Guides Hub — all ingredient and technique guides