Nestled between John Lewis and Next in the heart of Exeter, an unassuming-looking office block is host to a surprising urban crop - gourmet mushrooms. What is more, they are being grown from the city’s waste coffee grounds, gleaned from the likes of Starbucks and Costa Coffee. Using vacant office space and vertical growing to produce a protein-rich crop could be a solution to the food challenges of tomorrow, discovers Lucy Purdy when she meets those at the Fungi Futures CIC.

As shoppers scurry past, clutching early morning caffeine fixes, Adam Sayner swings open the doors to his workplace - the GroCycle Urban Mushroom Farm in the centre of Exeter. What may seem an unlikely spot for such an enterprise, in fact makes perfect sense, because these oyster mushrooms are being grown on used coffee grounds - a waste stream abundant in Exeter and most UK towns and cities, as we collectively slug down an estimated 80 million cups of the black stuff each day.

Inside, hanging like studded clouds high above, the mushrooms grow quickly on huge bags of grounds suspended from the ceiling. The 300m2 farm is capable of producing 150 kilos of oyster mushrooms each week, a crop prized by restaurant and food-lovers alike for their superior taste. The coffee grounds are collected from the city’s coffee shops each morning by a GroCycle cyclist pulling a trailer and provide the perfect mix of nutrients for the mushrooms to feast on and grow. Crucially, the grounds are already sterilised – and remain so if used within 24 hours – removing the need for the farm to repeat this time and energy-consuming process.

“A cup of coffee is at the end of a process where less than one per cent of the coffee plant is used,” explains the director of Fungi Futures CIC, (the social enterprise which launched GroCycle,) Adam Sayner.“The grounds contain exactly the kind of nutrients which the mushrooms feed on and they are a waste product that would otherwise end up in landfill. This problem can only increase as the UK’s booming coffee industry is set to keep on growing. In all sorts of ways, growing mushrooms in this way made perfect sense to me.”

And what is more the local restaurants and shops which GroCycle supplies are eager to take the crop given that the oyster mushrooms are tasty, low in calories, high in protein, fibre and iron and also contain significant traces of the elements zinc, potassium and selenium as well as many vitamins. Mycologist and author of six books about mushrooms, Paul Stamets, calls oyster mushrooms “exceptional allies for improving human and environmental health”.

In many ways, the business takes the natural cycle as its inspiration. Adam says, “Fungi are the great recyclers of the Earth. In nature they play a vital role in breaking down organic matter and returning it to the soil. They have evolved incredible enzymes which can break down the complex bonds in plant matter, returning them to the ecosystem and making use of them as their own food source. This innate ability to transform waste products into highly nutritious and edible food can be applied to great benefit in our modern societies where organic waste is abundant. Woodchips, sawdust, coffee grounds, brewery waste, cardboard, paper – these are all materials that the versatile oyster mushroom will happily grow on.”

With land and resources under increasing pressure, Sayner explains, one thing we do have is truckloads of waste and mushroom farms are one method of converting this into tasty, healthy protein. “The future will undoubtedly involve more mushrooms grown from ‘waste’,” he says.

GroCycle is also keen to get other people growing mushrooms - schools, parents, children, food-lovers and gardeners, as well as city dwellers who are short of time and growing space.Hence it markets GroCycle Mushroom Kits for £16.50 which allow people to produce mushrooms at home in just 14 days. The spawn, or seed, in these kits makes use of another waste stream – spent brewery products. Each week, spent grain and hops are collected from local micro-brewery the New Lion Brewery in Totnes and used as the food source for producing the spawn. This is then mixed with the coffee grounds.

Adam is looking too into opportunities to turn the waste stream – the nutrient-rich coffee-based compost left after growing the mushrooms- into a commercial compost or biofuel.

He is also considering how to share what he has learned and is currently looking at ways to replicate his urban farm model. One recent development is the growing system GroCycle has helped set up a in a Devon prison and it is hoped to roll this out to other prisons particularly where it will help inmates gain qualifications. The team are also devising an online course about mushroom growing in response to expressions of interest they have received from all over the world.

So, how might this project help meet the world’s future food needs? Not only does this type of mushroom farm re-use waste but it also requires minimal energy input, offering a low-impact alternative to energy-intensive meat production while, crucially, still growing a protein-rich food. So, why not keep an eye out when you’re next shopping or running for the bus? You might spot an urban mushroom farm springing up near you.

Do try this at home

Adam offers these simple tips to get the most out of growing mushrooms at home with your GroCycle Mushroom Kit:

• Place your kit in a shaded spot, away from radiators, draughts and direct sunlight to stop it drying out;
• Spray with tap water twice a day to keep it nice and humid;
• Watch closely every day - it’s amazing to see how quickly the mushrooms develop!
• Harvest when the caps have opened up and the edges are just starting to turn upwards;
• After you have harvested a first crop, dunk your kit in water overnight to increase the yield of the second crop.

Images courtesy of “GroCycle”

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