True espresso must be made entirely from arabica beans, which have half the caffeine of the alternative robusta variety.

ECONOMIST: Espresso coffee

Other local coffee roasters include Coffee Assembly, a pioneer that began roasting in 2006, and Glory Coffee and Fahrenheit 500, both of which supply roasted beans for 18 Grams and Espresso Alchemy.

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Stell traveled from Oregon to Atlanta, Georgia, for the Specialty Coffee Association of America expo, where the show floor was filled with nearly 800 booths featuring everything from exotic coffee beans to the latest Italian espresso machines.

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Located in a chic part of the 7th arrondissement with a modern and airy decor, Coutume offers a menu of daily-changing coffees in several incarnations -- espresso, decaf and filter -- the beans for which are sourced by the owners and roasted onsite in the enormous roasting machines at the back of the shop.

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It grinds beans to order and dispenses coffee, espresso or ristretto, one or two cups at a time.

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But if two beans in 100 are duds, the chances of a bad espresso are unacceptably high.

ECONOMIST: Espresso coffee