Espresso: Mastering the art of extraction under pressure

1 hour ago

3 min read

Espresso machine pours coffee into a cup of crema; beans on a table, light background with a plant. Text: La Réminiscence, L'espresso.

Espresso is the most demanding—and arguably the most fascinating—extraction method in the world of coffee. In less than 30 seconds, a machine forces hot water through a compact dose of ground coffee, revealing a dense, complex beverage crowned with a golden crema.

At La Réminiscence, each microlot is roasted with consideration for the diversity of extraction methods. Some coffees are best enjoyed as espresso, others as filter coffee. Understanding what truly constitutes an espresso allows you to choose better, prepare better, and appreciate it more fully.

What exactly is espresso?

Espresso is a pressure extraction method. Water at 88–94°C is forced, at 9 bars of pressure, through a disc of finely ground and tamped coffee. The extraction lasts between 20 and 30 seconds to produce 25 to 45 ml of liquid.

What distinguishes espresso from any other method is its concentration: the aromas, oils, and sugars of the coffee are extracted quickly and intensely. The crema—that golden-brown foam on the surface—is the sign of a fresh and successful extraction. It forms thanks to the CO₂ still present in the freshly roasted coffee.

Espresso machine pouring brown coffee into a white polka-dot cup, close-up, warm atmosphere.

The fundamental parameters of espresso

The grind: the most important variable

A grind that's too coarse results in an under-extracted espresso: acidic, watery, and lacking body. A grind that's too fine leads to an extraction that's too long, bitter, and astringent. The grind must be precisely adjusted according to the coffee used, the ambient humidity, and the machine's pressure. This is a parameter that needs constant adjustment.

The dose/yield ratio

The espresso ratio is calculated by weight: input dose (ground coffee) versus output yield (extracted liquid). A classic ratio for a "traditional" espresso is 1:2 — 18 g of coffee to 36 g of liquid. A "long" or "lungo" ratio can go up to 1:3 or 1:4. In specialty coffee, even more precise ratios are often used.

Temperature and pressure

The ideal temperature is between 88 and 96°C, depending on the variety and roast. Light roast coffees, which tend to be acidic, benefit from a higher temperature. More complex coffees, with a sweeter, chocolatey profile, express themselves best at a slightly lower temperature.

What type of coffee makes a good espresso?

This method is very revealing: both flaws and qualities are amplified. A good specialty espresso relies on well-roasted coffee, from carefully selected origins, with sufficient rest after roasting — generally 6 to 8 weeks — for the CO₂ to partially dissipate and the aromas to stabilize.

At La Réminiscence, our numbered microlots are selected according to their extraction potential. Some offer a dense crema and notes of melting chocolate, while others reveal intense fruity aromas in espresso that surprise at first glance but enchant on the palate.

Bag of black coffee labeled No. 3 La Réminiscence, with a partially filled white cup on a light background.

Making espresso at home: practical tips

To prepare a quality espresso at home, a few principles apply: grind your coffee at the last minute, preheat your machine and cup, and weigh your doses. A barista scale isn't a luxury; it's the tool that transforms a rough routine into a repeatable process.

Espresso is a practice. Every machine, every cup of coffee, every morning requires a slight adjustment. It is precisely this attention to detail in each cup that makes it one of the most rewarding experiences in the world of coffee.

What if your next espresso started with a new discovery? Explore La Réminiscence specialty coffees and find the microlot that suits you, from chocolatey sweetness to fruity vibrancy.

Discover our coffees and extend the experience in your cup.