How to Make Mushroom garum
Mushroom garum is a modern adaptation of ancient Roman fish sauce, using mushrooms instead of fish to create an intensely umami liquid condiment through koji fermentation. Pioneered by chefs at Noma, it offers deep savory depth for vegetarian and vegan cooking.
Category: Pastes & Sauces · Method: Fungal/Mold · Time: 3-12mo · Difficulty: 3/5 · Yield: varies · Temp: 18-22°C
History
Ancient garum was made by fermenting fish and salt in the Mediterranean sun. The concept was reimagined in the 2010s by the Noma fermentation lab, substituting mushrooms and koji to create plant-based alternatives. Their work popularized a new category of amino-rich fermented condiments.
Ingredients
- 1 kg Mixed mushrooms — Shiitake, cremini, button, or wild mushrooms - stems included
- 200g Barley koji — Or rice koji
- 120g (10% of combined weight) Sea salt — Non-iodized
- 200ml Water — Non-chlorinated
Equipment
- Food processor or blender
- Large glass jar or fermentation vessel
- Cheesecloth or fine mesh strainer
- Sous vide setup or warm spot (60°C)
- pH strips
- Fine filter or coffee filter
- Dark glass bottles for storage
Instructions
Prepare mushrooms
Roughly chop mushrooms (stems too - they're flavorful). Pulse in food processor until coarsely ground but not puréed.
Time: 15 min
Tip: Don't over-process - some texture helps fermentation.
Combine ingredients
Mix ground mushrooms, koji, salt, and water in a large bowl. Stir thoroughly to distribute koji and salt evenly.
Time: 10 min
Tip: The salt prevents bad bacteria while koji enzymes work.
Pack and seal
Transfer to fermentation vessel. Pack down to remove air pockets. Seal with lid or cover tightly.
Time: 10 min
Tip: A vacuum-sealed bag works well for even fermentation.
Ferment warm
Maintain at 60°C for 8-12 weeks. Use sous vide, dehydrator, or warm spot. Stir weekly if possible.
Time: 8-12 weeks
Tip: Consistent warmth is key. 60°C is ideal for koji enzyme activity.
Strain the garum
Strain through cheesecloth, pressing to extract all liquid. For clearer garum, filter again through coffee filter.
Time: 1-2 hours
Tip: The solids (mushroom paste) can be used as a seasoning too!
Pasteurize and bottle
Heat garum to 80°C for 15 minutes to pasteurize and halt fermentation. Cool and bottle in dark glass.
Time: 30 min
Tip: Pasteurization stabilizes and mellows the flavor.
Fermentation Timeline
- Day 1: Combine ingredients — Mushrooms, koji, salt, water mixed and sealed.
- Week 1: Enzymes activate — Koji begins breaking down mushroom proteins.
- Week 2-4: Flavor develops — Amino acids and umami compounds form.
- Week 4-8: Deepening — Complex savory flavors intensify.
- Week 8-12: Peak development — Maximum umami achieved.
- After straining: Ready — Strain, pasteurize, bottle, enjoy.
Signs of Success & Spoilage
Good signs
- Deep brown color
- Intensely savory, meaty aroma
- Liquid separating from solids
- pH dropping (4.5-5.5 range)
- No off-odors or mold
Warning signs
- Mold growth on surface
- Putrid or rotten smell
- Pink or unusual colors
- Fizzing (unwanted fermentation)
- Extremely low pH (too acidic)
Troubleshooting
- Mold developing
- Cause: Temperature too low or air exposure Solution: Increase temperature to 60°C. Ensure anaerobic conditions. Remove mold if early.
- Weak flavor
- Cause: Not enough time or too cold Solution: Continue fermenting. Check temperature is consistently 60°C.
- Too salty
- Cause: Salt ratio too high Solution: Dilute finished garum with water. Use less salt next time (minimum 8%).
- Bitter notes
- Cause: Fermented too long or too hot Solution: Strain and pasteurize to stop. May mellow with time.
- Won't strain clear
- Cause: Over-processed mushrooms Solution: Multiple straining passes. Accept some cloudiness - it's natural.
Storage
Dark glass bottles in refrigerator Keeps 1-2 years refrigerated after pasteurization. A little goes a long way - use drops, not pours. Flavor intensifies over time.
Health Benefits
- Rich in naturally occurring glutamates (umami)
- Contains mushroom-derived nutrients
- Low calorie flavor enhancer
- No added MSG
- Vegan source of deep savory flavor
- Contains B vitamins from koji
Serving Suggestions
- Drops in soups for depth
- In salad dressings
- Finishing grilled vegetables
- In vegan gravy and sauces
- Added to stir-fries
- In marinades for tofu or tempeh
- Anywhere you'd use fish sauce or soy sauce
- In bloody marys for umami
Related Pastes & Sauces Ferments
Other Fungal/Mold Ferments
- Miso — Condiment
- Tempeh — Legumes & Soy
- Shoyu — Legumes & Soy
- Tamari — Legumes & Soy
- Doubanjiang — Legumes & Soy
- Gochujang — Legumes & Soy
- Tauco — Legumes & Soy
- Meju blocks — Legumes & Soy