Mycoprotein is made by growing a naturally occurring soil fungus in large fermentation tanks, feeding it a simple diet of glucose and nutrients, then harvesting and processing the resulting biomass into a protein-rich food ingredient. The whole process resembles brewing beer more than farming, and it can produce high-protein food continuously, around the clock. Here’s how each stage works.
The Fungus Behind It All
Mycoprotein comes from a single species of fungus called Fusarium venenatum, a microorganism commonly found in soil. The strain used in commercial production is grown under tightly controlled, sterile conditions to ensure consistency and safety. It was selected because it naturally produces long, threadlike filaments (called hyphae) that give the final product a fibrous, meat-like texture, something most other microorganisms can’t replicate.
The protein content of the resulting biomass is over 40%, with a balanced amino acid profile. It’s also naturally rich in dietary fiber, vitamins, and minerals, which makes it unusually nutritious for a single-ingredient protein source.
What Goes Into the Fermenter
The fungus needs five core elements to grow: carbon, hydrogen, oxygen, nitrogen, and phosphorus. In practice, these come from glucose (the carbon and energy source), oxygen pumped into the tank, ammonia (for nitrogen), and phosphoric acid (for phosphorus). A mineral mix supplies the remaining trace elements the organism needs, including potassium, sodium, calcium, magnesium, iron, copper, manganese, and zinc. These collectively make up about 4% of the final biomass.
The glucose is typically derived from food-grade carbohydrate sources like wheat or corn starch, diluted and heated to around 30°C before being pumped into the fermenter. Researchers are also exploring the use of agricultural waste products and industrial byproducts as cheaper carbon and nitrogen sources, which could further reduce production costs.
Continuous Fermentation
The production method that sets mycoprotein apart from most fermented foods is that it runs continuously rather than in batches. Fresh nutrients flow into the tank while biomass is steadily drawn off, allowing the fungus to keep growing without interruption. This is fundamentally different from, say, brewing beer, where you start a batch, let it finish, then start over.
The fermenters themselves are among the largest continuous-flow culture systems in biotechnology. They use an air-lift design rather than mechanical stirrers. Instead of blades churning the liquid (which would shear the delicate fungal filaments and ruin the texture), bubbles of air rise through the tank, gently circulating the contents and delivering oxygen at the same time. This low-shear environment is critical: it lets the hyphae grow long and intact, which is what eventually gives mycoprotein its characteristic meat-like chew. Air-lift fermenters also use less energy than stirred tanks, keeping the overall environmental footprint smaller.
The tank is held at a constant temperature, and the fungus grows in a sterile (axenic) environment, meaning no other organisms are present. This level of control ensures the product is consistent from one day to the next.
Harvesting the Biomass
Once enough fungal biomass has accumulated, it’s separated from the liquid growth medium. The two main methods for this are filtration and centrifugation, both of which effectively strain the solid fungal mass out of the surrounding broth. What you’re left with is a pale, dough-like paste made up almost entirely of those long fungal filaments.
RNA Reduction: A Critical Safety Step
All rapidly growing cells contain high levels of RNA, a molecule involved in building proteins. In most foods this isn’t a concern, but when you’re harvesting fast-growing microorganisms, the RNA concentration can be unusually high. If you eat too much of it, your body breaks it down into uric acid, which at elevated levels becomes a risk factor for gout.
To address this, the harvested biomass is rapidly heated to above 68°C while still in the broth and held at that temperature for 20 to 45 minutes. This heat treatment breaks the RNA down into small fragments that naturally diffuse out of the cells, reducing the RNA content to less than 2%. The process is simple but essential: it’s what makes mycoprotein safe to eat in meaningful quantities.
Turning Paste Into Meat-Like Texture
The raw mycoprotein paste doesn’t look much like food yet. Turning it into something that resembles chicken, beef, or mince requires a texturization step, and the most common industrial method is freezing. As ice crystals form within the paste, they push the fungal filaments into organized, parallel arrangements. When the ice melts away, what remains is a layered, fibrous structure that mimics the grain of animal muscle.
Binders play an important supporting role here. Ingredients like sodium alginate (a seaweed-derived gelling agent) strengthen the protein network through hydrogen bonding and other molecular interactions, improving the structural integrity of the final product. At concentrations around 0.6 to 0.8%, sodium alginate significantly enhances the elasticity of the mycoprotein matrix and helps maintain fiber continuity even after freezing and thawing.
Some newer production methods use 3D printing-style extrusion, where the paste is pushed through a nozzle. The shear forces generated during extrusion physically align the fungal filaments along the direction of flow, mimicking the orientation of real animal muscle fibers. When combined with gelling agents and freezing, this approach can produce remarkably convincing meat analogues with layered, pull-apart textures.
Regulatory Approval and Safety Profile
Mycoprotein went through an unusually long approval process. The UK Ministry of Agriculture, Fisheries and Food approved it for food use in 1983 after a 10-year evaluation. The US FDA designated it “Generally Recognized as Safe” in 2002, and Quorn products entered the American market that same year.
Like any protein, mycoprotein can trigger allergic reactions in a small number of people. But the rate is remarkably low. A 2015 systematic review by the York Health Economics Consortium examined 30 experimental studies and confirmed only 2 allergic reactions. Over a 15-year surveillance period, true allergic reactions (the kind involving an immune response) occurred at a rate of roughly 1 per 9 million packages sold, or 1 per 24.3 million servings. That makes it far less allergenic than common triggers like peanuts, tree nuts, or shellfish.
Why the Process Matters for Sustainability
The continuous fermentation approach is inherently efficient. The fungus converts simple sugars into protein-dense biomass quickly, using far less land and water than raising livestock. It can also run on agricultural byproducts and industrial waste streams as feedstocks, which keeps costs down and reduces waste. Because the process takes place in sealed tanks rather than open fields or feedlots, it generates significantly less carbon dioxide per gram of protein than conventional meat production. The air-lift fermenter design adds another efficiency advantage, requiring less energy for mixing than traditional stirred-tank systems.
This combination of high protein yield, low resource input, and small carbon footprint is the core reason mycoprotein has attracted interest as a scalable alternative to animal agriculture.