Serious side of coffee
By VIRGINIA WINDER
THERE’S no stopping a coffee roaster browning beans.
Especially not those producing short, sharp, shots in New Plymouth, New Zealand.
“I’ll call you back in 10 minutes – I’m in the middle of roasting some beans,” says Inca-Fe’s Karen Hodson.
Ozone roaster Paul Newbold keeps checking the colour of his batch, leaping to action as the barrel roaster beeps, then opens the hatch for the hot beans to pour out for a quick cooling.
Wild Cat’s Jude Nagel explains why a coffee roaster relies on fine timing as surely as a stand-up comedian.
“It’s a matter of 30 seconds,” she says. “It’s so temperamental – a couple of flicks (of her bean testing scoop) and a couple of looks, then it’s gone too far.” 
She roasts beans from Papua New Guinea, Columbia, Kenya and Guatemala in a 5kg Probat machine for her boutique business in central New Plymouth. Nagel holds green beans from different countries in each hand. Those from PNG are slightly larger and smoother than those from Columbia, which have a mottled appearance and cook faster.
These are all high-quality Coffea arabica beans, as opposed to the lower-quality Coffea canephora beans, known as robusta, not used by New Zealand roasters.
There is a third kind of bean, Coffea liberica, which has an acrid taste and has little economic significance worldwide.
She heats her machine up to 210 degrees Celsius, then adds the beans. The temperature immediately drops to 150 degrees and she ups the gauge to maintain an even heat of 160 degrees.
“You put in 5kg and get out 4.9kg,” she says, explaining how moisture is lost.
Nagel picks up a bucket of fresh beans and peels back the lid so the aroma of a French roast is released. “It’s the C02 that’s coming out.”
On storage, she recommends that people take their beans out of the bag they come in, pour them into an air-tight container and keep in a cool, dark place, like a pantry.
“And definitely not the fridge or freezer – that dries out the beans.”
Paul Newbold is hot on the roasting process, which he has been doing for eight years. “I’m definitely going for 10. I’ll be the old guy they won’t be able to get rid of,” he grins.
The Ozone roaster sweats behind a 12kg machine (a 45kg machine waiting in the wings), checking his batch with a practiced eye while talking.
He designs roasting profiles (cooking methods) for the origin beans Ozone gets from around the globe.
Newbold won’t reveal any of his secret recipes, but talks generically about the batches and more specifically about chemistry of roasting beans.
He says the first stage of coffee roasting is called endothermic, when the beans absorb heat. The second step, often called the first crack, happens when the beans double in size and turn light brown.
They then release energy or heat, which is called the exothermic step. This is followed by a short endothermic period, and then another exothermic step called the second crack, which is quicker. 
“Most New Zealand roasters take 15 to 20 minutes to roast their beans,” Newbold says.
The cooling process should be done in under four minutes. “Otherwise the beans go dull – it mutes the flavours,” he says.
Jamie and Karen Hodson are immersed in the science of coffee, with a white board covered in chemical reactions and explanations.
Their expertise is the tasting, or “cupping” process, which Newbold also does at Ozone.
On their Inca-Fe boardroom table glasses are lined up like a five-against-five tequila slam competition.
Each 150ml glass is filled 8.25 grams of freshly roasted and ground beans. On one side, the beans have been dry processed while green and those on the other half have gone through the wet process. This means the just-picked beans have been fermented in water for 72 hours before being dried.
Our job is to sniff the grinds of each kind.
The dry-processed beans smell of blueberry and vanilla. Those put through the wet method have hints of Indian spices and are earthier.
“It’s quite a strict protocol for cupping,” says Karen. “This is the international standard for rating coffees.”
Jamie continues: “Cupping coffee is much the same as tasting wine and you are meant to spit. You have to, otherwise you’d go nuts.”
Next, just-boiled water is poured on the grinds until the glass is filled. After four minutes the sniffing starts again.
“Once the process starts, you don’t talk,” Jamie says.
He has cupped for up to two hours, testing 20 coffees in one session. “It’s quite intense.”
The now-steeped dry coffee smells of nutmeg and sugar, while the wet one gives off a whiff of hazelnut and maybe almonds.
Next we use a spoon to “break the cake” on the surface of the cup. The dry coffee is back to blueberry and the wet is now clearly hazelnut and vanilla.
Then it’s time to taste. We each have a larger cup to spit into, before sucking up coffee from a spoon. Karen and Jamie suck up their brew like kids supping soup.
They aren’t being bad mannered; it’s important to get air in with the taste test so the smell of the coffee is sucked up into the nasal passages.
“Flavour is made up of 80% aroma,” Karen explains.
The crema, or reddish-brown foam on a good cup of espresso, is similar to the head on a beer. “They are effervescent bubbles that burst. That’s why it’s important to have crema on espresso drinks.”
Just to prove a point, after the cupping is over, she makes flat whites with surfaces rich with deep veins of fragrant crema.
Learning the science of coffee is a big buzz.
