How to Make Tamari

Tamari is a Japanese soy sauce made with little or no wheat, resulting in a deeper, less sharp flavor than regular shoyu. Originally the liquid byproduct of miso making, tamari has become prized for its rich, complex umami taste. It's naturally gluten-free (when made without wheat) and has a thicker consistency.

Category: Legumes & Soy · Method: Fungal/Mold · Time: 6-18mo · Difficulty: 3/5 · Yield: varies · Temp: 18-22°C

History

Tamari originated as a byproduct of miso production in Japan, with the name meaning 'to accumulate' - referring to the liquid that pooled as miso aged. This 'liquid miso' was eventually recognized as a valuable condiment in its own right, leading to dedicated tamari brewing that emphasizes soybeans over wheat.

Ingredients

  • 4 cups (800g) Soybeans — Dried, whole - more than regular shoyu
  • 1/4 cup (50g) Wheat (optional) — For traditional tamari; omit for gluten-free
  • 2-3 tsp Koji starter (Tane-koji) — Aspergillus oryzae; higher inoculation rate ensures dominance over spoilage bacteria on protein-rich beans
  • 1.75 cups (350-400g) Sea salt — Non-iodized; essential for 15-18% brine concentration to ensure safety during long aging
  • 6 cups Water — Non-chlorinated

Equipment

  • Large pot
  • Incubation setup (30°C)
  • Fermentation crock
  • Pressing equipment
  • Cheesecloth
  • Dark storage bottles

Instructions

  1. Cook soybeans

    Soak soybeans overnight. Pressure cook for 40-60 minutes or boil until very soft (4-6 hours). Drain well and reserve liquid. Cool beans to 30-35°C. For dedicated tamari, some traditional methods involve mashing beans into 'miso-dama' (balls) before inoculation.

    Time: Overnight + 6 hours

    Tip: Beans should be soft enough to crush easily between your thumb and pinky finger.

  2. Make koji

    Mix cooled beans (and toasted wheat if using) with koji spores. Ensure even distribution. Incubate in a humid environment at 30-35°C for 48-72 hours. Monitor temperature closely; if the beans exceed 40°C, the koji may die or produce off-flavors.

    Time: 48-72 hours

    Tip: Legume-only koji requires slightly higher temperatures and better aeration than rice koji to prevent bacterial spoilage.

  3. Prepare moromi

    Dissolve the salt in water to create a strong brine. Combine the finished bean koji with the brine in a fermentation vessel. The mixture will be much thicker than standard shoyu moromi.

    Time: 1 hour

    Tip: A high salt concentration is critical here to prevent the high-protein beans from rotting during the long ambient fermentation.

  4. Ferment and Stir

    Ferment for 6-18 months at 18-22°C. Stirring schedule: Stir daily for the first 2 weeks to aerate and manage yeast; stir weekly for the remainder of the first month; then stir once a month until finished. Keep the vessel covered with a breathable cloth or a loose lid.

    Time: 6-18 months

    Tip: Regular stirring in the early stages is vital to prevent the growth of surface molds and to ensure even salt distribution.

Fermentation Timeline

  • Week 1: Koji development — Soybean-heavy koji forming. Dense, aromatic mass.
  • Month 1-3: Initial fermentation — Dark color developing. Thick moromi. Active bubbling.
  • Month 6-12: Deep development — Intense umami. Rich, dark color. Thick consistency.
  • Month 12-18: Full maturity — Complex, mellow flavor. Restaurant-quality tamari.

Signs of Success & Spoilage

Good signs

  • Dense koji growth
  • Very dark moromi
  • Thick liquid
  • Intense umami aroma
  • Smooth, rich taste

Warning signs

  • Black mold
  • Rotten smell
  • Slimy texture
  • Sour taste

Troubleshooting

Too thin
Cause: Too much water in moromi Solution: Use less water in future batches. For current batch, you can simmer the liquid after pressing to concentrate flavors.
Not dark enough
Cause: Under-fermented or temperature too low Solution: Age longer. The Maillard reaction and enzymatic browning require time and stable ambient temperatures.
Surface mold
Cause: Insufficient stirring or low salt Solution: Scrape off white yeast/mold immediately. If mold is black or fuzzy, and has penetrated deep, discard. Ensure salt ratio is at least 15% of total weight.

Storage

Dark glass bottles, sealed Keeps Pasteurized: 3+ years. Raw: 1 year refrigerated. Keep away from light and heat.

Health Benefits

  • Higher protein than regular soy sauce
  • Gluten-free option available
  • Rich in antioxidants
  • Contains isoflavones
  • B vitamins
  • Umami reduces need for salt

Serving Suggestions

  • Sashimi dipping sauce
  • Gluten-free cooking
  • Finishing sauce for vegetables
  • Marinades for proteins
  • Soup seasoning
  • Dressing base

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Authoritative food-safety sources

This site cross-references but does not replace professional guidance. For canonical, peer-reviewed fermentation safety information, consult:

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