Some like 'em long, some like 'em short, and some like 'em all. But what exactly is an espresso ristretto? You're about to find out.
The word ristretto literally means "restricted" in Italian: In an espresso's case, that means the barista has "restricted" the amount of water that flows through the coffee, essentially making a shorter, stronger brew. If a standard double espresso typically yields about 2 ounces of finished coffee liquid from 14 to 18 grams of ground espresso beans, then a ristretto might clock in with slightly less volume—probably something closer to an ounce and a half.
In practice, this means that instead of cutting the espresso off when the streams turn completely blonde as they out of the machine, the shot would be considered done as soon as any yellow appeared. (During an espresso extraction, the color of the coffee changes along a spectrum of browns: Dark chocolate to ochre, chestnut to amber, and, finally, blonde.)
The resulting beverage will usually put a bit more hair on your chest than an average espresso shot. Because the coffee flavor is far less diluted and the body noticeably heavier, ristrettos pack a stronger punch on your tongue. What they might not have more of, however, is caffeine: Less water through the coffee grounds can mean that less of the caffeine solubles actually dissolve into your cup, so while the taste is considerably bolder, a ristretto isn't necessarily going to keep you awake nights any more than a fully extracted espresso might.
On the flip side, while a lungo, or "long" shot, could technically mean that the barista has let more water run through the ground coffee, it might also imply that he or she has simply added more volume (or elongated, if you will) a standard shot of espresso by adding a little bit of hot water to the finished brew. This provides a little extra liquid without contributing any excessively bitter flavors to the cup (which is the first thing that happens when espresso is overextracted).
Personally, I prefer my espresso shots poured over a tiny bit of hot water—maybe as little as half an ounce—in order to let the flavors open up a bit. You know, like adding the perfect splash of water to a fine scotch.
How about you: Long, short, or something in between?