It all came about when Graeme Rogerson and brother-in-law Tyson Downing were having one of those “I wonder…” conversations. If food such as pizza tastes so much better in a wood-fired oven, would it work for roasting coffee, they wondered. So they decided to have a go.

Today, they batch-roast high-quality arabica coffee beans in a hand-built woodfired roaster housed in a bunker down by the railway tracks in Frankton, Hamilton.

Being hands-on, DIY types they knocked up their first roaster themselves. Using the copper inner from a recycled water heater and a battery drill to rotate the drum, they built a tiny machine that roasts about two tablespoons of coffee.

“We built it ourselves because we love doing that sort of thing,” Graeme says. “He’s a plumber and I’m a sparky and we wanted to make an invention. We really didn’t know if it was going to work. We surprised ourselves when we said, ‘Hey, it really does make great-tasting coffee.’”

He explains, “The flavour is a whole lot warmer, sweeter and more complex than that from a gas-fired roast. It’s a full, rich, mellow flavour with an excellent mouthfeel, it coats your mouth and has a lingering taste. I say it’s like eating a coffee.”

Most coffee roasters are powered by gas, but Manuka Brothers coffee is roasted over the glowing embers of manuka wood; hot air and gas from the burning wood, as well as infrared energy radiating from the glowing embers, roast the beans. It’s this double-edged roasting energy that gives Manuka Brothers beans a more complex, fuller, warmer, smoother roast. Because the design of the roaster gives excellent combustion the beans are not ‘smoked’.

After experimenting with different types of wood, such as kanuka and apple wood (which imparted a sourness and bitterness to the roast), they’ve settled on roasting over good-quality manuka. As far as they know, they are the only people wood-roasting coffee on a commercial scale in the southern hemisphere.

Soon their ambitions outstripped the tiny roaster, so it was time to think big. Well, a bit bigger. Once again rolling up their sleeves, Graeme first made a plywood and polystyrene mock-up before they welded together a new roaster, affectionately christened Black Betty. That was in the dying days of 2013 and she’s still in use, with just a few modifications and repairs along the way. Though bigger than the first roaster, Black Betty still only has a capacity of 6-10kg, a fraction of the 30-60kg that most gas roasters handle. Keeping things at this scale means they can do small batches of special roasts.

“We roast what we like,” says Graeme, “and we don’t do green blends.” Green blending is when a selection of green beans are taken and roasted all together. It saves time and labour and gives a greater output, but the compromise is that none of the beans are roasted to their best. At Manuka Brothers they roast each single-origin bean to the roast depth that captures the flavours of that batch of beans, then they blend to get the flavour profile they want.

Today Manuka Brothers’ Coffee Roastery is a family blend of Graeme and Angela Rogerson, Liz and Tyson Downing. Tyson and Liz run the cafe and the roastery, with Tyson being chief roaster. Graeme takes more of a background role running the office, and Angela, a graphic designer, has created all the roastery’s logos and signage.

Every weekend Graeme mans the Manuka Brothers’ little yellow coffee cart, at Cambridge Farmers’ Market on Saturdays and Hamilton Farmers’ Market on Sundays. Over eight hours at the weekend markets, Graeme reckons they’ll pour more than 600 coffees. Next to the coffee cart you’ll find Liz and Angela’s dad, Peter, selling bags of beans, and compostable, Nespresso-compatible coffee pods.

In 2015, deciding that Black Betty needed a new home, Graeme and Tyson set about converting a former railway building into a cafe and roastery. Formerly used to store detonators, it’s a trapezoid-shaped building with a cast-concrete roof, walls and floor, hence its nickname – the Bunker. In converting the empty shell those DIY skills came in again, with Tyson and Graeme doing everything themselves, including fashioning light fittings and restoring a beautiful, rusty iron fire door. “It’s a secret hideaway with five or six tables and a little outdoor space,” Graeme says. “We made a space that we would want to hide in.” /