Once it's in the cup, it's easy to tell espresso from a so-called "regular" cup of coffee. But at what point exactly do the two streams diverge? Espresso should be understood as simply a form of preparation and not a kind of coffee. But aren't some coffee beans prepared specifically with espresso brewing in mind? Before the Single Origin espresso craze, wasn't blending once a "thing" we admired in terms of balancing a coffee to make it produce wonderful shots? Absolutely.
The basic theory behind espresso blending is to create a layered set of flavors that respond well to the intense mode of brewing that is espresso. Layering allows the coffee roaster to control the sensory balance of acidity, sweetness, and body in a coffee—specifically in a coffee that's going to be brewed to accentuate all of the characteristics of the beans in a less-than-subtle way.
"I think blending is kind of a lost art," says Gabriel Boscana, Director of Green Coffee at Sightglass Coffee Roasters in San Francisco. "We focus a lot on single origin [unblended] espressos these days, which is not a bad thing. But I do think the layering of flavors is really hard to do." In terms of finding one single kind of coffee bean that evokes the right balance of sweetness, body, and acidity, Boscana says, "it's really going to be tough to find a supercomplex single origin that's going to hit all of those points. They're out there. But really tough to find."
Thus, almost every roaster offers a blend of coffees for espresso that attempts to check all those sensory boxes while creating a coffee that's versatile enough to taste great as a single shot or as a macchiato, cappuccino, or latte.
But how do you decide which coffees to blend, and how, and at what ratios? At Sightglass, the Owl's Howl Espresso blend is currently a mix of coffees from Guatemala, Costa Rica, and Ethiopia. Boscana explained why they chose the coffees they did:
"Most Guatemalan coffees are kind of big, they have a lot of chocolate, some fruit. So you have that as the base of the coffee. The Costa Rica is the middle: simple, clean and sweet. The Ethiopian coffee is the high note, it's where the brightest acidity comes in. It's really clear, with good clarity—it's like the soprano of the three. And that's what you want to finish with," said Boscana.
"The Guatemala is the first thing you taste, it's tactile, it's big. Then the flavor moves to the middle palate, and you get the Costa Rica: caramel, sweet, simple sugars, nothing too complicated, medium weight. And then once you finish the shot, the finish should be the light, floral citrus finish of the Ethiopian Sidamo. Pleasant and not acrid or sour. You work up to the lightest notes as you're drinking the espresso. That's the idea."
Of course, that's only one theory on blending and there are myriad others. Brazilian coffees, for instance, are widely popular as espresso "base" components due to their hefty, super-sweet profiles. Blends are also often created with technical needs in mind: a roaster can build a complex, finicky blend that tastes wonderful on an espresso machine operated by a superexpert barista. Or it can fall into the hands of someone who simply can't make it taste right. Blending the right coffees in the right ratios so that it's hard to mess up a shot—that's where the art of blending really comes into play.
And what about roasting?
"There's two schools of thought, and many roasters go back and forth, or they just fight about it. One school of thought is that you don't roast for espresso, you just roast for the optimal flavor of that coffee and it's up to the barista to make it delicious," says Boscana, who himself believes you should roast a coffee specifically for the brew method—espresso—you're preparing it for.
"I think you should roast for espresso, because it goes back to purpose. What do you want to say with this? What is the purpose of this coffee? Usually this means you roast a little bit longer, and a little bit darker. Those profiles can look, on a graph, very different from each other, and for the most part it's a little bit longer and hotter, and darker because you do want to accentuate more body. Espresso's ALL tactile: you want to accentuate body and sweetness, tone down the acids a bit so it's more pleasant," said Boscana.
"Espresso is such a violent, concentrated thing, that anything you would taste in the filter brew is going to be accentuated in the espresso."
That said—is it wrong to brew an "espresso roast" coffee as drip, or vice versa? Not if it tastes good to you, says Boscana. "It's all that person's experience," says the veteran roaster. "You're not in their mouth."