White Miso (Shiro)

White miso (shiro) is the sweet, pale, mellow end of the family — high koji, low salt, and a short, controlled age. The abundant koji floods the paste with amylases that sweeten residual starch, so it finishes in weeks rather than years. Perfect for dressings, light soups, and a quick turnaround. This recipe follows the Base Miso Ratios sweet row.

Ingredients

Work entirely by weight. A “Jar” is a quart/litre wide-mouth jar (~0.75 kg paste); a “Crock” is a 2 L crock or fido (~3 kg paste). White miso runs koji-forward (2 : 1).

Component	1 Jar (~0.75 kg paste)	1 Crock (~3 kg paste)
Rice koji (2 parts)	470 g	1,880 g
Cooked soybeans (1 part)	235 g	940 g
Salt (~5% of base paste)	35 g	141 g
Reserved bean cooking liquid	as needed	as needed
Reserved salt for the surface	~3 g	~12 g

Note

Salt is ~5% of the base paste (koji + cooked beans). For 1 Jar: base paste = 470 + 235 = 705 g; salt @ 5% = ~35 g. Stay in the 5-6% band — this is the floor that keeps a low-salt miso safe, and it only works because the age is short and cool. The dry-salt calculator sizes the dose.

Yield

About 740 g finished paste per Jar / 2.9 kg per Crock. Make in smaller batches — white miso is best used fresh within a few months of finishing.

Calculated values

• Dry-salt %: ~5% of base paste weight (5-6% range — do not go lower).
• Koji : soybean: ~2 : 1 (high koji = sweet, pale, fast).
• Target finished pH: ~5.0-5.5 — above the 4.6 line. Salt-and-water-activity preserved, not acid-preserved.
• Aging temperature: 18-25 °C / 64-77 °F, controlled (warmer than red, because the age is short).
• Aging time: 3-8 weeks.

Info

Salt percentage and aging time move together. A 5% white miso is only safe because it finishes in weeks at a controlled 18-25 °C — the lower salt is a weaker hurdle, so you must not push it into a long warm age. Never extend a low-salt miso into months at ambient temperature; that is what the higher-salt red miso is for.

Readiness window

	Detail
Early	Weeks 1-2: still pale, koji sweetness emerging
Maturing	Weeks 3-6: light tan, mellow, raw edge fading
Done	3-8 weeks at 18-25 °C
Arrest	Refrigerate at 2-4 °C as soon as it tastes balanced

Done when: the paste is pale tan, smells sweet and mellow with no raw-bean note, and tastes balanced and lightly sweet. Because the age is short, taste from week three and move it to the fridge the moment it’s where you want it — over-aging a sweet miso darkens and coarsens it.

Method

Cook the soybeans soft

Soak soybeans overnight, then simmer until a bean crushes effortlessly between two fingers. Reserve some cooking liquid. Cool to body temperature so you don’t scald the koji enzymes.

Weigh and salt by base-paste weight

Mash the beans coarse. Weigh beans + koji together — that is the base paste. Calculate salt at 5% of that combined weight, then mix the salt evenly into the koji first, holding back a pinch for the surface.

Combine to a packable paste

Fold the koji-salt into the mashed beans. Add reserved cooking liquid until the paste holds like firm cookie dough — wet enough to pack with no air pockets, dry enough not to slump.

Pack airtight and weight

Press the paste into the jar in fistfuls, knocking out air as you go. Smooth the top, dust with the reserved salt, lay a sheet flush against the surface, add a follower and weight, and seal.

Age short and warm, then arrest

Hold at 18-25 °C / 64-77 °F for 3-8 weeks. Check weekly — low-salt misos move faster and want closer watching. A little white kahm yeast at the edges is normal; scrape and re-smooth. As soon as it tastes sweet and balanced, refrigerate at 2-4 °C to hold it.

Tip

For an extra-sweet white miso, push koji to 2.5-3 : 1 and hold salt at the 5% floor — but keep the age even shorter and cooler, because lower salt and higher sugar narrow the safe window.

Caution

Do not drop salt below ~5%, and do not extend a sweet miso into a long warm age — at low salt the salt hurdle alone holds the paste above the botulism line, and that only works for a short, controlled ferment. White miso typically finishes around pH 5.0-5.5; taste is never a safety test. A small edge film of white kahm is fine; black, fuzzy mold growing into the body means discard. See Mold vs Kahm.

Variations / mix-ins

• Chickpea white miso: swap chickpeas for soybeans — sweeter, paler, and milder still.
• Yellow split pea (peaso): an even quicker, mellow pale paste.
• Barley koji: earthier and a touch less sweet.

See also

• Making Miso — the full build, packing, and surface-management workflow
• Base Miso Ratios — koji:legume:salt master formulas and scaling table
• Rice Koji and Growing Koji — make the enzyme engine first
• Red Miso — the long-aged, high-salt counterpart
• Dry-salt calculator and Salt Percentage
• Safety and Botulism