The Breville machine was also the only semi-automatic model to produce a velvety, well-incorporated foam. The consistency with which it incorporated air made for a beautifully textured latte—and our coffee expert was even able to make some latte art with it (something that was impossible with the air bubbles from other models, including the Gaggia and all of the less expensive machines).
The piston-driven, or lever-driven, machine was developed in Italy in 1945 by Achille Gaggia, founder of espresso machine manufacturer Gaggia. The design generically uses a lever, pumped by the operator, to pressurize hot water and send it through the coffee grinds. The act of producing a shot of espresso is colloquially termed pulling a shot, because these lever-driven espresso machines required pulling a long handle to produce a shot. Lever-driven espresso machines are sometimes called manual espresso machines because of this.
While clever baristas are always coming up with twists on common coffee staples, the most popular beverages are based on a shot or more of espresso and steamed milk with a layer of foam artistically placed on top. Cappuccino is among the most popular espresso-based drinks, but with some clever applications of milk and cream, they sky is the limit as to what you can create.
A portafilter (or group handle) attaches to the grouphead of semi-automatic and piston-driven espresso machines, and carries a tamped puck of coffee grounds within its basket. It is usually made of brass for better heat retention, and is attached by a plastic or wooden handle. The portafilter forms a seal with the espresso machine's gasket, and directs high-pressure hot water through the coffee puck. After-market retailers also sell bottomless portafilters that minimize the espresso's contact with any metal. A bottomless portafilter is one tool baristas use to analyze the quality of the coffee grind and the evenness of the extraction and allows for a visual check of "channeling" or the condition in which water is able to pierce a hole in the espresso puck during the brew process leading to poor extraction. Often, baristas use knockboxes to store their spent espresso grounds after they have pulled a shot.