Kikkoman soy sauce contains non-organic, likely GMO soybeans and wheat, plus sodium benzoate preservative. Fortunately, it contains no seed oils. This authentic DIY version uses organic ingredients and traditional 6-18 month fermentation, eliminating artificial preservatives for a cleaner product with superior flavor depth.
Based on: Soy Sauce
· Makes approximately 40 servings
· Serving: 1 tablespoon (15ml)
Why This Recipe is Seed Oil Free
Commercial Soy Sauce from Kikkoman often contains inflammatory seed oils like canola, soybean, or sunflower oil. This homemade version replaces them with healthier fats like butter, ghee, coconut oil, or avocado oil — giving you the same great taste without the processed oils.
200g (about 1 cup dried) · Eden Foods Organic Black Soybeans or Lundberg Organic Soybeans
Primary protein source that provides umami through fermentation and amino acid development
Organic wheat berries
200g (about 1.25 cups) · Bob's Red Mill Organic Hard White Wheat Berries
Provides carbohydrates for koji culture and contributes to complex flavor development during fermentation
Unrefined sea salt
100g (about 6 tablespoons) · Redmond Real Salt or Celtic Sea Salt
Creates proper salinity for fermentation, inhibits harmful bacteria while allowing beneficial microbes to thrive
Koji starter culture
5g (about 1 teaspoon) · Cultures for Health Aspergillus Oryzae Koji Starter
Essential mold culture that breaks down proteins and starches into flavorful amino acids and sugars
Filtered water
500ml initially, plus additional for salt brine · Reverse osmosis or spring water (avoid chlorinated tap water)
Medium for fermentation and final dilution - quality matters as chlorine can kill beneficial microbes
Instructions
Step 1. KOJI PREPARATION (Days 1-3): Steam 200g organic soybeans for 3-4 hours until completely tender - they should mash easily between fingers. Separately, roast 200g organic wheat berries in a dry pan for 10-15 minutes until fragrant and lightly golden, then crack them coarsely in a food processor (not powder, just broken pieces). Cool both completely to room temperature.
Step 2. INOCULATION: In a sterilized large bowl, combine the cooked soybeans and cracked roasted wheat. Sprinkle 5g koji starter evenly over the mixture and mix thoroughly with clean hands for 3-4 minutes until every grain is coated. The mixture should feel slightly damp but not wet - if too dry, mist lightly with sterilized water.
Step 3. KOJI INCUBATION: Transfer to a sterilized shallow tray or perforated container lined with clean cloth. Cover with another damp cloth and place in a warm environment (80-86°F/27-30°C) for 48-72 hours. Check every 12 hours - the mixture should develop a sweet, nutty aroma and visible white mold growth. Mist the cloth if it dries out, but don't oversaturate.
Step 4. MOROMI PREPARATION (Month 1): Once koji is fully developed (completely covered in white mold), transfer to a sterilized crock or food-grade plastic container. Dissolve 100g sea salt in 500ml filtered water to create 20% salt brine. Pour over koji, ensuring mixture is completely submerged - add more salt water if needed maintaining 20% salinity.
Step 5. FERMENTATION (Months 1-18): Cover container with cheesecloth secured with rubber band. Store at cool room temperature (65-75°F/18-24°C) away from direct light. Stir weekly with clean wooden spoon for first month, then monthly thereafter. The mixture will darken and develop complex umami flavors. Taste after 6 months - continue aging up to 18 months for deeper flavor.
Step 6. STRAINING AND FINISHING: When desired flavor is reached, strain through fine mesh lined with cheesecloth, pressing solids to extract maximum liquid. For crystal-clear soy sauce, strain again through coffee filters. Optional: gently heat to 140°F/60°C for 30 minutes to pasteurize and stop fermentation, then cool completely.
Step 7. STORAGE: Transfer to sterilized glass bottles or jars, leaving 1/2 inch headspace. Unpasteurized sauce keeps 6-12 months refrigerated and continues to develop flavor. Pasteurized version keeps 2+ years in cool, dark storage. Use 1 tablespoon (15ml) as direct substitute for commercial soy sauce in any recipe.
Storage
Store finished soy sauce in glass containers in refrigerator for up to 12 months if unpasteurized, or 2+ years if pasteurized. Natural sediment may form - this is normal and can be strained out. Never use plastic containers for long-term storage as they can leach chemicals.
Cost Comparison
Cost per serving (homemade)$0.24
Cost per serving (store-bought)$0.12
Savings-100%
DIY costs twice as much per serving but delivers superior nutrition, authentic flavor complexity, and eliminates GMOs and preservatives. The upfront ingredient investment creates multiple batches, and the artisanal quality justifies the premium cost.