Quorn: fermented filamentous fungi we can eat

Moulds, like those used to make blue cheese, are a form of fungus, as are the yeasts that are used to make wine or beer. But, it turns out fermented fungus can impart more than just a tasty extra to foods like cheese. “Quorn”, the vegan-friendly meat alternative, is a fermented food made from a filamentous fungus, and Paul Dyer from the University of Nottingham is a fungal biologist and expert on “single cell protein” the stuff that Quorn is made from. Chris Smith asked him what form this fungus takes, and how it was found in the first place...

Paul - To give it its Latin name Chris, it's called Fusarium venenatum. And as you said, importantly, it's a filamentous fungus, which means it grows by producing microscopic, tube-like threads called hyphae, which helps give it its meat-like textures. These resemble the muscle fibres, and interestingly, the group of Fusarium as a whole, are perhaps better known for causing some serious plant diseases. But fortunately this particular Fusarium species is non-harmful and instead is very good to eat.

Chris - How did it get discovered? Did somebody actually set out to find a particular filamentous fungus that would have the characteristic of meat in terms of its texture? Or was it an accident?

Paul - It goes back to the late 1960s when there was thought to be a looming crisis, with a worldwide shortage of protein, and a company, Rank Hovis McDougall, made a worldwide search of microbes that could convert starches, which was plentiful at the time, to protein. And that involved collecting over 3000 fungi from all around the world and testing them for suitability, for protein production, and safety in industrial fermentation. And a funny story was that, although they looked all over the world for these, the best fungus they found came from the garden compost heap of one of the research scientists, just a few miles away from their own doorstep. And that was in Marlow, Buckinghamshire. So it was right on their doorstep all along.

Chris - So when you're eating things like Quorn, you are actually eating someone's compost heap almost. But what's involved in the process then of turning that fungus, which is a microorganism, into something that does resemble meat. How do you go from A to B?

Paul - Well, there's really, I think, three stages. First of all, you need to grow the fungus. And the Fusarium is grown in some of the world's largest industrial fermenters and these are loop shape fermenters about 50 metres tall, containing about 160,000 litres of growth medium, which has got all the sugars and nutrients necessary for fungal growth. And the fungus is effectively pumped round them by jets of air. And so within the fermenter the fungus is constantly growing. Secondly, you then need to harvest the fungus. So once the growth in fermenters has reached a certain growth state, some of the fungal material is siphoned off to make Quorn. And the production process is designed so that as the fungus is removed, more fungi are growing in the fermenter to replace that that's removed.

Chris - How do you stop it getting, Oh, sorry. I thought you'd finished. I was going to just jump in and say, how do you make sure it doesn't get contaminated? How do you make sure that it's purely just the nice fungus in there and you don't get other stuff going in, which could sort of hijack the process and poison people.

Paul - Yeah. Because that's always a problem with fermentation. So in the case of Quorn, it does use a sterilised fermenter and also all the nutrients and airflow that you're adding to it are also sterilised. So it's only the pure filamentous fungus that's growing in there.

Chris - And you were going to go on to say the final process is presumably turning the fungus you tap off into something meat-like?

Paul - That's it precisely. So once the fungal hyphae has been harvested, that then undergoes various processing stages such as, there's a little bit of egg protein added in the vegetarian version, or some alternatives in the vegan one. And that helps you form a matrix, which has got this characteristic meat-like flavour fibers. And then there's also various flavourings and colourings that are added to get the Quorn mince or nugget, you know, whatever your favorite Quorn might be.

Chris - And just in 30 seconds, is it nutritionally good for us to eat this stuff? Do you get all the stuff you need from it that you should get from meat?

Paul - Yeah, it's basically a relatively high protein. So it's got similar protein to white meat. It's got all the essential amino acids, particularly beneficial though, is it's got high fibre content, and low fat content. So it really is a good meat substitute.

Chris - Yes, indeed. A high fibre intake is good for your bowel health, isn't it? But talking of health, it's important to consider beyond just the health of the consumer, because there is also the environment here as well. How does Quorn as a meat substitute compare in terms of its environmental footprint with equivalent meat production?

Paul - Yeah, so I think it can be argued that Quorn has got several significant environmental benefits relative to traditional meat consumption. For instance, some work has been undertaken by the Carbon Trust, which when it looked at greenhouse gas emissions found that it was only about 10% of that of beef production, and 25% of it for chicken. And also given the current problems with global freshwater and land shortages. It also only uses about 10% of the levels of beef and half that of poultry. So as well as the health benefits it does have these environmental benefits as well.

Chris - Can we feed the fungus on stuff that we would traditionally regard as a waste product? Are they not fussy eaters in the sense that we could actually take things we would throw away and then use those as the feedstock to produce the Quorn?

Paul - Very good question. I think you've been reading our recent research grants.

Chris - Well actually I haven't but tell me more.

Paul - So traditionally the fungus is grown on quite pure glucose and various other nutrients that have to be supplied to it, but there are some ongoing studies of which I'm partly involved in, seeing if we can grow on alternative sugar sources, such as sugars produced from the break down of straw, and various other plant material that would otherwise go to waste. So that's definitely one of the moves looking forward into the future of Quorn production.

Chris - Well, I was wondering if you could team up with Michael and all the whey, which is full of sugar from the cheese industry that they chuck away could come your way.

Paul - That's a very interesting idea. I'm also involved in some cheese products as well, and I know that there's a lot of interest in trying to use that whey. I don't think we've actually tried feeding Quorn on those particular sugars. So a very nice idea, Chris.