Episode Details

Doppio simply means double, and a standard doppio yields 60 milliliters, about 2.0 US fluid ounces, brewed from twice the ground coffee in a larger portafilter basket. The single shot, or solo, came first, and its size was not chosen for flavor. It was the most coffee early lever machines could extract, since forcing water through a swollen bed of grounds at nine bars, roughly 130 pounds per square inch, took a barista's arm on a spring loaded piston. Motorized pumps removed that limit, and outside Italy the doppio became the default shot.

That default reshaped café workflow. When you order a single, most bars pull a full doppio through a two spouted portafilter and catch one stream in your cup, because swapping baskets and regrinding would stall the line. Competitions turn the same split into a test: baristas pull two doppios at once into four cups, and any uneven tamp shows up as a mismatched cup. For all that precision, a doppio's caffeine ranges from 58 to 185 milligrams, depending on the bean.

• The phantom second stream is often poured straight into the drip tray, since time costs a café more than beans.
• Changing to a single basket alters the depth of the coffee bed and forces the barista to redial the grinder.
• An off axis tamp creates a channel, pouring bitter over-extracted coffee from one spout and sour under-extracted coffee from the other.
• Arabica plants make less caffeine than robusta, and low altitude plants facing more insects produce more.
• The average doppio lands around 150 milligrams of caffeine, and darker roasts lose slightly more caffeine by volume.