How to Make Furu (tofu cubes)
Furu (腐乳), also called fermented tofu or tofu cheese, consists of tofu cubes fermented in brine with rice wine and often red yeast rice or chili. The result is creamy, pungent cubes with cheese-like texture used as a condiment, cooking ingredient, or spread. Flavors range from mild to intensely funky.
Category: Legumes & Soy · Method: Fungal/Mold · Time: 1-3mo · Difficulty: 3/5 · Yield: varies · Temp: 18-22°C
History
Furu originated in China during the Han Dynasty over 2,000 years ago. It spread throughout East and Southeast Asia, with regional variations developing - red furu in southern China, white furu in the north, and chili-spiced versions in Sichuan. It remains a beloved breakfast and cooking staple.
Ingredients
- 1 lb (450g) Firm tofu — Extra-firm works best
- 2 tbsp Sea salt — For dry-salting
- 1 cup Rice wine — For brine
- 2 tbsp Salt — For brine
- 2 tbsp Red yeast rice — Optional, for red furu
- 2 tbsp Chili flakes — Optional, for spicy version
Equipment
- Cutting board and knife
- Wire rack for drying
- Glass jars for fermentation
- Clean cloth or paper towels
Instructions
Prepare and Blanch Tofu
Cut extra-firm tofu into 1-inch (2.5cm) cubes. Briefly boil the cubes in salted water for 1-2 minutes to stabilize the protein structure and sanitize the surface. Drain and pat dry thoroughly.
Time: 30 min
Tip: Boiling helps the cubes maintain their shape during the long fermentation process.
Inoculation and Incubation
This is the critical 'pehtze' stage. Arrange cubes on a sterilized bamboo mat or rack, ensuring they do not touch. Inoculate with Actinomucor elegans or Mucor hiemalis spores. Place in a high-humidity environment (90-95% RH) at a controlled temperature of 15-20°C. Incubate for 2-5 days until a thick, white, velvety mycelium mat completely covers each cube.
Time: 2-5 days
Tip: Proper airflow and high humidity are essential. If any black, green, or yellow mold appears, discard the batch immediately.
Salting and Stabilizing
Carefully roll the mold-covered cubes in high-quality sea salt. Pack them into a sterilized jar in layers, sprinkling a small amount of additional salt between layers. Let sit for 24-48 hours to allow the salt to draw out excess moisture and firm the protein structure.
Time: 1-2 days
Tip: This step prepares the 'pehtze' for the long-term brining phase.
Brining and Aging
Prepare a brine consisting of rice wine (minimum 10-15% ABV) and salt. The final brine must have a salt concentration of 10-12% to ensure safety. Add flavorings like red yeast rice or chili. Pour over the cubes until they are completely submerged. Seal tightly and age at 18-22°C.
Time: 1-3 months
Tip: The alcohol and high salt concentration act as preservatives against anaerobic pathogens like C. botulinum.
Fermentation Timeline
- Days 1-3: Drying — Tofu cubes forming dry skin. Salt penetrating.
- Week 1-2: Mold growth — White fuzzy mold covering cubes. Beginning to smell fermented.
- Month 1-2: Brine fermentation — Cubes absorbing brine flavors. Texture becoming creamy.
- Month 2-3: Ready — Rich, pungent, cheese-like. Creamy throughout.
Signs of Success & Spoilage
Good signs
- Thick, white fuzzy mycelium during incubation
- Creamy, custard-like interior texture after aging
- Pungent, savory, and wine-like aroma
- Intact cubes that hold their shape until spread
Warning signs
- Black, green, or orange mold growth
- Slimy texture on the surface of the brine
- Smell of rot or ammonia
- Bubbling or gas pressure in the jar (sign of secondary fermentation/spoilage)
Troubleshooting
- Cubes dissolving into mush
- Cause: Salt concentration too low or insufficient alcohol content in the brine. Solution: Increase salt to at least 10-12% of the total weight and ensure rice wine is at least 10% ABV to firm the tofu proteins.
- Off-colors (Black/Green/Yellow) during incubation
- Cause: Contamination or temperature too high. Solution: Strictly maintain temperature below 20°C during the mold growth phase and ensure all equipment is sanitized.
- Sour or putrid smell
- Cause: Low salt or poor drainage during the initial drying phase. Solution: Ensure tofu is well-pressed and the brine is sufficiently salty to inhibit spoilage bacteria.
Storage
Keep cubes fully submerged in brine and store in a cool, dark place or refrigerator. Keeps 6-12 months. Safety Note: Ensure the brine maintains a high salt and alcohol content. If the pH is above 4.6 and salt is low, there is a risk of botulism in anaerobic conditions. Always use clean, dry utensils to remove cubes.
Health Benefits
- Protein from tofu
- Probiotics
- B vitamins (especially B12)
- Easily digestible
- Isoflavones
- Traditional medicinal uses
Serving Suggestions
- Congee topping
- Spread on steamed buns
- Stir-fry flavoring
- With rice
- Vegetable seasoning
- Substitute for cheese in vegan cooking
Related Legumes & Soy Ferments
Other Fungal/Mold Ferments
- Miso — Condiment
- Douchi (black beans) — Legumes & Soy
- Tempeh gembus — Legumes & Soy
- Stinky tofu — Legumes & Soy
- Blue cheese — Dairy
- Brie — Dairy
- Camembert — Dairy
- Roquefort — Dairy