Presta Coffee: Precision Roasting

Presta Coffee Roasters explores the science of roasting each bean

Curtis Zimmerman stands next to his roaster as it charges—he's heating it up to about 400 degrees Fahrenheit to prepare it for unroasted coffee beans. The beans go into the roaster a greenish beige and about 10 minutes later come out a light brown, but there's plenty going on in that ten minute span.

Zimmerman, who owns both Presta Coffee Roasters and Stella Java, tracks each roast with data input into a laptop. It records the time until first crack, a point in roasting that marks the beginning of the light roast range that is accompanied by an audible cracking noise from the beans, and the temperature it took to get the beans there, among other things. He keeps each bean's unique roasting profile saved and dialed in so, if he likes something, he can replicate it in the future.

He doesn't simply rely on the computer, though. Once the beans get close to the roast he's looking for, which for Presta goes in the light to medium range, Zimmerman is constantly smelling the beans and checking their color to be sure they're where he wants them to be.

It's this obsessive and honestly kind of nerdy approach that elevates Presta's coffee above most others, though there are a handful of other places in town that are picking up the torch as well. Other boutique third wave roasters in Tucson include EXO Roast Co., Yellow Brick Coffee and Café Aqui. In fact, when Stella Java was in its beginning stages, Zimmerman sourced his roasted beans through EXO for his shop.

He explains the decision to begin roasting on his own was all a matter of wanting to control the finished coffee he was selling as much as possible. However, it wasn't without its setbacks. Getting their espresso roast and blend took a while longer, so Stella Java continued to serve EXO espresso after using their own beans for drip and pour over coffees. Once he settled on an espresso blend, he says customers to the café, which is located in the Mercado San Agustin at 100 South Avenida del Convento, assumed that since they weren't using EXO, they weren't using locally roasted coffee.

Six months later, Stella Java has, as any good coffee shop does, a cult-like following of devotees who sit at the bar and doodle or work on laptops or read the paper, chatting with the baristas between sips of coffee. Zimmerman says since everyone's coffee preferences vary so much, it's almost as much about the atmosphere of a third wave shop as it is the coffee itself.

"It's about the personality of the shop and the type of people that you hire," he says. "Why one person goes to one shop over another? It all comes down to atmosphere."

The term third wave applies to the distinct epochs of coffee culture in this country that started with brew at home Folgers and moved to the Starbucks espresso drink scene, eventually culminating into a movement that's focused both on craft roasting and meticulous brewing. It is as much about the science of the coffee itself and how it reacts to heat and other stimuli as the art of a well-executed tulip on top of a latte.

It's about educating the customer, Zimmerman says, so they can go home and brew coffee that tastes as good as the cup they get at Stella Java. He says one of the most common mistakes is the amount of coffee grounds to water used to brew—he recommends 15 grams of water to 1 gram of coffee as a place to start.

However, it's also about sourcing from ethical, sustainable farms. For Presta, Zimmerman goes through Bodhi Leaf to source the chocolaty and caramely beans from Columbia, the bright and acidic beans from Ethiopia and coffee from just about every growing region in between.

"Even now the term third wave is a little passé, honestly," Zimmerman says. "It's not trendy to talk about it anymore."

In the future, Zimmerman says he expects to see coffee get a similar treatment as the craft cocktail movement with more unique drinks and a firm place in the upscale restaurants in town. Currently, Presta provides espresso for the neighboring Agustin Kitchen and bags of roasted beans for Time Market's multi-roaster retail wall, but he hopes that soon restaurants will begin incorporating boutique roasts on their menu the same way that they do small batch distillers' spirits or local farmers' produce.

Until then, Zimmerman plans to keep roasting for Stella Java. Before opening at the Mercado in December 2013, Stella Java was actually a small coffee cart in St. Mary's Hospital.

"I just wanted to be able to provide my wife with a good cup of coffee," Zimmerman explains. His wife, Stella, works at the hospital, but it wasn't long until the cart moved in and built out a space at the Mercado.

"No one wanted to come to a hospital lobby to get a cup of coffee," he says. "But even after it was a slow build of promoting Stella through the neighborhood."

Now Zimmerman is nearly ready to open the doors of his second coffee shop, which also serves as the roastery. Best of all, if you go to Presta Coffee Roasters, located at 2502 N. First Ave. north of Grant Road, on the right days once the shop opens in mid-May, you'll be able to catch a whiff of the freshly roasted coffee.

And that brings us right back to the batch Zimmerman is roasting. Before the beans come close to second crack, Zimmerman purges them from the roaster and into a large metal grate-lined basin that rotates as a fan underneath cools the beans in a matter of seconds. It's just one more way Zimmerman is sure that once he's decided the beans are roasted properly, they stay that way.

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