Free Miso Fermentation Ratio Calculator
Balance dry soybeans, rice koji, salt percentage, and pressing weights for authentic Japanese Sweet White (Shiro), Mild Yellow (Shinshu), and Dark Red (Akamiso) miso.
🥣 Miso Style & Batch Target
Fermentation Timeline: 4 to 8 weeks at room temperature
Salt as the Anti-Spoilage Barrier: Sweet white miso uses lower salt (4.5% - 6.0%) and must be stored in the refrigerator after 6 to 8 weeks to stop fermentation. Dark red miso has 11% to 13% salt, allowing safe multi-year room temperature aging as Maillard browning deepens the umami.
Recommended Tools & Equipment
Tested hardware and components for high reliability
The Three Pillars of Traditional Miso
Miso is a fermented paste created by blending cooked legumes (usually yellow soybeans) with grain inoculated with Aspergillus oryzae (koji) and sea salt. The mold's proteolytic and amylolytic enzymes slowly break down proteins into savory glutamate and starches into sweet glucose:
- Sweet White Miso (Shiro Miso): High koji-to-soy ratio (~2.2:1) and low salt (~5%). Ferments rapidly in 3 to 8 weeks. It produces a creamy, pale, mildly sweet paste ideal for salad dressings, glazes, and light soups.
- Medium Yellow Miso (Shinshu Miso): Balanced koji and soybean proportions (~1.2:1) with ~9% salt. Aged for 3 to 6 months. Versatile all-purpose miso with bright acidity and rounded umami.
- Dark Red Miso (Akamiso): Lower koji ratio (~0.8:1) and heavy salt (~12.5%). Aged for 1 to 2+ years. Long enzymatic digestion and Maillard browning turn the paste chocolate-brown with deep, complex, smoky umami notes.
The Soybean Cooking Multiplier
Dry soybeans absorb significant water during overnight soaking (12-18 hours) and simmering or pressure cooking:
Salt % = Salt_Weight / (Cooked_Soy_Weight + Koji_Weight + Salt_Weight + Liquid) × 100
Frequently Asked Questions
Can I use iodized table salt for making miso?
Never use iodized table salt or salt with anti-caking agents (like yellow prussiate of soda). Iodine inhibits the beneficial koji mold enzymes and wild yeasts, while anti-caking chemicals impart metallic off-flavors. Use pure non-iodized sea salt or kosher salt.
What is the liquid pooling on top of my aging miso?
That dark, aromatic liquid is tamari! It is pure, naturally extracted unpasteurized soy sauce pressed out of the bean mash under the weight of the drop lid. It is prized as a culinary delicacy.
What should I do if white fuzzy mold appears on the surface?
Surface mold on miso is common and usually harmless wild kahm yeast. Simply scrape away the top 1/4 inch (6mm) layer, wipe the container walls with vodka or grain alcohol, and re-sprinkle a light barrier of sea salt across the surface before replacing parchment paper.