How to Make Delicious Espresso? Illustrated Guide to Espresso Extraction with an Espresso Machine

The Foundation of Coffee Excellence: Understanding Espresso Extraction

Espresso-based beverages crafted with semi-automatic espresso machines continue to dominate the café market, even in today's era where single-origin and pour-over coffee have gained significant popularity. This becomes particularly evident at coffee exhibitions, where having a premium "La Marzocco" machine on display seems essential for maintaining a competitive edge.

The Barista's Essential Skill

If you aspire to become a barista, the first and foremost skill to master is espresso extraction. While extracting a single shot of espresso might seem straightforward, achieving consistency with every qualified shot presents an entirely different level of challenge. The numerous variables involved mean you must comprehensively understand the entire process to maintain complete control.

Characteristics of Quality Espresso

From an appearance perspective, quality espresso must display a golden crema—neither too thin nor excessively thick. When the crema is too thick, it becomes less fluid and prone to clumping. The ideal thickness is approximately half that of the underlying coffee liquid, with a fine texture free of large bubbles.

In terms of flavor, espresso should present burnt nut and chocolate notes with a creamy, full-bodied mouthfeel. The bitterness should linger briefly in the mouth, followed by a long, aromatic aftertaste.

The Critical Role of Coffee Beans

While these standards might appear simple on the surface, practical implementation reveals numerous challenges. The first crucial element is the coffee beans themselves. Coffee beans essentially determine the flavor direction of the entire beverage. In many instances when coffee tastes unpleasant, the barista cannot bear full responsibility. Transforming poor quality into excellence is the work of magicians—baristas have yet to achieve such miraculous abilities.

Therefore, if the inherent quality or flavor profile of the beans is suboptimal, no matter how advanced your techniques are for salvaging (or masking) the taste, your efforts will ultimately prove futile.

However, baristas must recognize and address certain issues. After all, many coffee beans do emphasize material quality, but sometimes the output quality fluctuates unpredictably. When such problems occur, they likely stem from the barista's insufficient understanding of the coffee beans. Many baristas adhere strictly to espresso extraction formulas, but FrontStreet Coffee suggests that overly data-driven extraction sometimes overlooks the inherent flavors of the coffee itself.

The Balance Between Data and Taste

Consider the case of a barista with five years of experience—a considerable duration in this profession. When calibrating espresso, he becomes overly fixated on data. Even when certain parameters produce espresso with excellent flavor and texture, if those numbers fall outside his accepted range, he readjusts completely.

The roast level and roasting time of coffee beans result in visibly different extraction behaviors. Espresso extraction should, like pour-over coffee, begin with the characteristics of the beans themselves, developing an extraction plan tailored to their specific properties.

The Extraction Process

When we reach the actual extraction phase, this becomes the barista's domain. While there appear to be numerous parameters to adjust—grind size, dose, ratio, water temperature, and pressure—along with various techniques to master—distribution, tamping, and so forth.

FrontStreet Coffee believes we should distinguish between primary and secondary parameters. For instance, water temperature and pressure are secondary parameters that, once set, typically don't require frequent adjustment. Meanwhile, grind size, dose, and ratio are primary parameters that are adjusted more regularly.

Understanding Grind Size

Grind size is the most frequently adjusted parameter. To understand this, consider that finer grinds create a more compact coffee puck, making it harder for water to pass through. Consequently, each unit of water extracts more coffee solids, resulting in a more concentrated beverage. The opposite holds true for coarser grinds.

However, it's important to recognize that extracting too many coffee solids isn't always desirable. While coffee contains approximately 30% soluble substances, it's widely accepted that only about 22% of these contribute positively to flavor, with the remainder producing unpleasant bitter and astringent notes.

The Impact of Distribution and Tamping

The influence of distribution and tamping on coffee extraction cannot be underestimated. Uneven distribution and improper tamping certainly can cause coffee flavors to develop negatively. However, in practice, as long as you fill the portafilter to its reasonable maximum capacity and achieve a level tamp (regardless of force applied), channeling and uneven extraction typically won't occur. In actual operations, numerous methods exist to prevent such issues from arising.

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