How Espresso Works

In the 1960s, specialty coffee shops were rare in the United States, but now they are a common sight in many cities. As highlighted in this article from Business Week Online, the renowned coffee chain Starbucks expanded from just 17 stores in Seattle in 1987 to over 5,500 locations globally.

Nowadays, espresso is widely available, from dedicated coffeehouses to compact drive-thru stands. Many cafeterias, bookstores, and other venues serve espresso-based beverages, and shopping malls often feature espresso carts or kiosks. With a variety of flavored syrups and preparation methods, there are countless ways to savor your espresso. Whether it's a latte, cappuccino, or Americano, what makes these small, potent cups of coffee so captivating?

This article explores the essence of espresso and the key elements required to consistently brew a flawless cup every time.

What Is Espresso?

Espresso isn’t defined by a specific type of coffee bean but rather by the method of extracting flavor using nearly boiling water and pressure. It can also describe the beverage produced by this process, as in "I'll have a cup of espresso, please."

Pronounced ess-press-o, not eX-press-o, the term espresso comes from Italian, derived from caffè espresso. While many assume it relates to speed (as in "express"), it actually stems from the past participle of esprimere, meaning "to express" or "to press out." Thus, caffè espresso translates to "pressed-out coffee." Espresso is believed to have originated in Italy around the 1900s, when Luigi Bezzera patented a machine that forced hot water and steam through coffee grounds into a cup.

In Italy, the art of brewing exceptional espresso is guided by "the four Ms:"

This can be roughly translated into English as:

To truly grasp the essence of espresso, one must delve into the espresso experience. Most espresso enthusiasts emphasize that flavor is paramount. Enjoying a great cup of espresso goes beyond mere taste; it’s about the harmonious blend of aroma and flavor. To test this, try sipping espresso while holding your nose. You’ll detect the bitterness of caffeine but miss the rich, full-bodied flavor that comes from the coffee’s aroma.

Let’s delve deeper into the key components that contribute to crafting the ultimate espresso experience.

Beans

Espresso beans undergo a longer roasting process compared to regular coffee beans, allowing their oils to surface. While opinions vary on the best bean type, Arabica beans are praised for their balanced blend of flavor, acidity, and bitterness. Although Robusta beans are often considered lower in quality, they produce more crema (the golden-red foam atop a perfect espresso) and complement Arabica beans exceptionally well.

Crema is what elevates espresso beyond just strong, concentrated coffee. It also helps preserve the volatile oils, enhancing the drink’s signature aroma by slowing their release into the air after brewing.

To achieve the finest espresso, always opt for the freshest beans. Older beans tend to become overly oily and develop a stale smell. Store your beans in an airtight container, keeping them in a cool, dark, and dry location. Avoid freezing them, as this can cause moisture to crystallize and damage the beans’ porous structure, ultimately diminishing their flavor.

Grind

A single espresso shot uses 7 to 9 grams (roughly ½ tablespoon) of finely ground coffee beans for every 2 ounces (4 tablespoons) of water. This yields a 1.5 oz. shot of rich, concentrated coffee with a bold, bittersweet flavor and a thick, syrupy texture. Once ground, the beans’ oils are exposed to air, causing them to oxidize and lose flavor rapidly, which also impacts the crema. For the best flavor and aroma, grind your beans just before brewing.

Espresso grind is significantly finer than that used for regular coffee, almost powdery yet with a slight grittiness, akin to superfine sugar. This fine grind creates the necessary resistance for water to pass through effectively. While blade grinders (which use rotating blades) are known to produce inconsistent grinds by chopping rather than grinding, burr grinders are far superior. Whether manual or electric, burr grinders cut beans into uniform pieces, ensuring optimal flavor extraction.

Once the correct amount of ground coffee, or dose, is measured, it is gently yet firmly packed into the gruppa, a perforated metal cup. The grounds must then be tamped to ensure even compaction, as loose grounds allow water to flow too quickly, resulting in weak coffee. Various tamping tools are available, with flat-bottomed ones being the most popular, though some prefer rounded versions. Achieving the perfect tamping pressure—neither too hard nor too soft—is crucial. Proper extraction time is also key; with the right dose and tamp, a single espresso shot should take 25-30 seconds to brew.

Machine

Espresso can be made using two primary methods: steam and pump. Steam models include stovetop boilers, such as Moka pots, and countertop pressure units. Moka pots, popular in Europe, are affordable and compact but often criticized by espresso enthusiasts for producing a bitter brew due to the high temperature of steam-driven water. This method lacks crema and can sometimes result in a burnt taste. Countertop pressure machines, equipped with steam wands for frothing milk, offer a decent espresso experience and are ideal for occasional or semi-regular use.

Pump machines, commonly found in espresso bars, are the top choice for serious espresso lovers. These units maintain water at just below boiling point (around 192°F) and use steam pressure measured in atmospheres. The steam is forced through the coffee grounds either manually or mechanically, yielding the most consistent and flavorful espresso.

The price of espresso machines varies widely, from as low as $50 for a basic Moka pot to several thousand dollars for high-end pump models.

Maker

The quality of an espresso hinges on the skill of its maker. A dedicated barista will prioritize using premium beans, ground to the ideal consistency, and brewed with a reliable machine.

Cleanliness plays a crucial role in espresso preparation. Residual coffee grounds can taint the flavor, resulting in a subpar brew. Grinders should be cleaned thoroughly at least once a week, using a stiff brush (like a toothbrush or paintbrush) for the grinding plates and a soft cloth for other parts. Avoid using water on electric grinders! Espresso machines require daily cleaning, or immediate cleaning after use, to prevent oil buildup that could compromise flavor.

Ways to Enjoy Espresso

If plain espresso isn’t to your liking, there are numerous espresso-based beverages to explore. Many cafes offer unique signature drinks, but some classic recipes remain consistent across the board:

Milk Matters

Milk plays a crucial role in espresso-based drinks, often masking imperfections in the espresso. Frothing milk is an art, requiring precise techniques. Ideally, milk should not exceed 150°F, just below the point of being too hot to touch in a metal container. The goal is to create a rich foam layer, achieved in 30-45 seconds for 6 ounces of milk (enough for two cappuccinos) using a steam wand and gentle up-and-down motions.

Dedicated espresso enthusiasts may roast their own beans, debate tamping pressure, crema quality, water types, and the merits of pump versus steam methods. However, enjoying excellent espresso at home doesn’t require such extremes. Mastery comes with practice—the more you make and savor espresso, the better your results will be.