Growing Gourmet Mushrooms from Zero-Waste Whiskey By-Products with Canterbury Brewers & Distillers
- Growing Kent & Medway
- Jan 7
- 4 min read
Updated: 3 days ago
Canterbury Brewers & Distillers, an award-winning Kent spirit producer, used support from Growing Kent & Medway to solve their primary waste problem. One of our medium-sized grant programmes helped prove they could utilise whiskey by-products – spent grain, water, and CO₂ – to cultivate speciality gourmet mushrooms, creating new high-value food products and a true circular economy model.
At A Glance: Project Quick Facts
Project Lead: Canterbury Brewers & Distillers (Jon & Jodie Mills)
Collaborators: New collaborations secured post-project with MMR Research, Annandale Distillery, and Canterbury Christ Church University
Total Funding: £27,622 (Grant Awarded: £13,811 / Co-investment: £13,811)
Key Findings: Achieved 100% success rate growing two varieties of oyster mushroom. Found the mushrooms contain scientifically verified unique compounds. Potential yield: 160kg weekly per batch.
Food System Areas:
The Challenge: A Growing Waste Problem in Central Canterbury
Jon and Jodie Mills, the owners of Canterbury Brewers & Distillers at The Foundry BrewPub, had already successfully designed a system to pump waste heat from their stills to warm their adjacent restaurant. This early win spurred them to tackle their next sustainability hurdle.
As co-owner Jon Mills reflected on the problem: "I started worrying about what else we waste, and how we utilise that waste." With their whiskey production growing, the increasing volume of spent grain, water, and CO₂ created by their expanded operation became the focus. Simply disposing of this massive quantity of by-product was not viable for their business or for the environment.
The Innovative Idea: A Distillery-Powered Mushroom Farm
This mounting problem required a radical solution. The key to solving it lay in a flash of inspiration, as co-owner Jodie Mills recalls the moment the idea struck: "Jon woke me up at about 2:00 a.m. in the morning saying, 'Mushrooms!' And I think that's where the journey began."
This led to the strategic decision to commercialise a unique circular system: cultivating high-value speciality oyster mushrooms entirely on-site. This elegant system creates a double environmental win: it reuses waste grain while capitalising on the heat from the mash – a porridge-like mixture of grains – which helps with the pasteurisation process, avoiding the need for costly, energy-intensive processes typically required by mushroom growers.
The Approach: From Back-of-Brewery Trials to a Proven Process
The idea began with hands-on trials. "I started playing at the back of the brewery," Jon explained, and "started to see if I could grow mushrooms on the waste grain." To move from what they considered a "wacky" idea to a scalable business, they needed systematic R&D to demonstrate the viability of the substrate and growing conditions.
The methodology involved an eight-month trial to develop the correct substrate formulation, test two varieties of oyster mushroom (Black Pearl and Blue Oyster), and establish the optimal growing conditions using the waste grain, water, and CO₂ from the brewing process. This R&D process was essential to validate the concept before committing to a larger expansion.
The Results: Scientifically-Proven Quality and Commercial Success
The trials were a resounding success, achieving a 100 per cent success rate with both mushroom varieties. The quality was immediately evident. "I believe the mushrooms taste better than what's out there on the market," Jon stated. "We've had them scientifically tested to prove that our mushrooms are different – the compounds in the mushrooms we're growing are different."
Commercial validation was immediate. The newly grown mushrooms were added to the BrewPub's menu, with consumption increasing sharply from 1 kg per week to at least 4 kg per week. Trial results also indicated a significant scale potential, with a single whiskey batch yielding around 160 kg of mushrooms weekly.
See it Differently: Turning Brewery Waste into Gourmet Mushrooms
Looking Forward: A New Tourist Attraction for Kent
With the concept proven, Jon and Jodie are now focused on scaling their vision. They plan to build a new facility to house a micro-brewery, distillery, and a fully functioning mushroom farm, designed as a zero-waste tourist attraction. As Jon puts it: "I think it'll be the making of the business."
This expansion promises to generate high-value jobs in Kent and supports the region's commitment to food security and net-zero resource efficiency. The success has also opened the doors to exciting new collaborations with Canterbury Christ Church University and global research companies.
Why This Project Worked: The Second Harvest Principle
 | The project demonstrated a high-value return on investment, with the business matching the grant funding on a 1:1 basis. This shared investment successfully de-risked the trial of a novel "waste-to-value" system, proving that high-risk, high-reward innovation is accessible to smaller producers without requiring massive capital outlay. |
 | This initiative provided a practical blueprint for the circular bioeconomy. By repurposing unavoidable by-products – spent grain, waste heat, and CO₂ – into high-value biological inputs, the model successfully decoupled business growth from increased resource consumption. It proved that environmental sustainability and commercial profitability can be mutually reinforcing. |
 | The technical execution was exceptional, achieving a 100% success rate across the growing trials. Beyond reliable yields, the project delivered scientific validation of the mushrooms' nutritional profile, identifying unique bioactive compounds that elevate the end product from a simple food item to a premium, scientifically verified ingredient. |
Our Support: Enabling the R&D Partnership
This ambitious R&D project was supported by one of our medium-sized grant programmes. The funding provided the critical capital for the eight months of intensive trials and validation.
The support was crucial for overcoming initial barriers. As Jon concluded in his report: "Growing Kent & Medway has had a real positive impact on our business... We would not have got to this next exciting stage without their support and funding. I would highly recommend Growing Kent & Medway funding opportunities to any business who has the drive to make a difference."
