Fresh Cup Magazine, providing specialty coffee and tea professionals with unique insight into the trends, ideas, products and people that shape their world.
Issue link: http://freshcup.epubxp.com/i/105573
L ast year, Nuova Simonelli unveiled the Aurelia T3, a trickedout piece of equipment that now serves as the official espresso machine of the World Barista Championship. It's the object that competitors from around the globe use at that contest, as well as the regional and national events that lead up to the WBC. Among the bells and whistles on the Aurelia T3 is a series of PID controllers, or digital gizmos that manage a machine's temperature to within a tenth of a degree. "The T3 is a multi-boiler machine, and each grouphead has its own PID-controlled water boiler to heat the water," says Roberto Bresciani, president of the North American arm of the Italy-based company. "Then the metal on the grouphead is controlled by another PID with a heating element. Both things are getting controlled with a PID— it's the most rock-solid temperature-stable machine." Nuova Simonelli is one of many manufacturers taking increased measures to incorporate temperature stability into its models. As more and more espresso-machine companies are drawing a line between temperature control and shot quality, they're turning to PID controllers to ensure that the heat is on— and easily controllable—in their machines. In addition to temperature control, another buzzed-about espresso-machine technology term is "pressure profiling," which is the ability to manipulate the amount of pressure being placed on coffee grounds during an espresso extraction. While not as prevalent at this stage as PID controllers, pressureprofiling machines are starting to make their way into cafés. What do you as a café owner need to know about temperature and pressure? Read on as we break down the nuts and bolts of each. STEADY HEAT PID stands for three long words—proportional, integral and derivative—but the scientific talk will stop there. Essentially, a PID controller aims to help a machine of any kind minimize fluctuations—in the mechanized world, PID is used to stabilize such things as speed, flow and pressure. When it comes to espresso machines, the PID focus is temperature: A user will set the temperature of an espresso-machine boiler to the desired number, and a PID controller—using a control unit, relay and temperature probe—will produce that temperature to within one-tenth of a degree. "PID control is pretty much instantaneous to where it's maintaining that temperature all the time," says Jimmy Wardell, service manager at General Espresso Equipment, manufacturer of Astoria espresso machines. (It's worth noting that PID is also utilized in many home thermostats.) And how does it work? Tommy Gallagher, who regularly uses PID-controlled machines as he visits New York City cafés in his technical services job with Counter Culture Coffee, describes it in plain terms: "A PID knows how hot you want stuff to be, and it will figure out that it only needs to turn itself on for a couple of seconds for the water to meet this temperature," he says. "It figures out how to pulse the heating element at an appropriate rhythm to maintain a temperature instead of just shutting off when it gets to the desired temperature." And why is temperature control important? As baristas are increasingly interested in being able to tweak every variable to produce the best shot possible, knowing exactly what temperature you're working with gives you complete control of that element. "You can do everything exactly the same every single time," Gallagher says, "but your shot can come out differently every single time. You don't really know how to compensate for that in a consistent, measurable sort of way. Being able to have a more accurate sense of how hot things are—and knowing that it's going to [remain] that hot—allows you to more consistently make better things." Temperature's effect on an espresso shot is scientific and simple. "Hotter water makes things dissolve faster, and colder water makes things dissolve slower," says Gallagher. This will have continued on page 34 freshcup.com February 2013 33