What espresso characteristics matter most during extraction?

Espresso is made by forcing high-pressure hot water through finely ground coffee in a short time, producing a small, concentrated liquid. Two hallmarks define a standard shot: a golden-brown layer of crema on the surface and a strong, lasting taste impact on the palate. Both come from the extraction method rather than from any single bean.

Crema forms because roasting creates gas inside the beans; high-pressure water dissolves carbon dioxide, and when the liquid returns to normal pressure the gas escapes as tiny bubbles. Using a commercial single-group coffee machine as an example, operators control dose, yield, and time to keep shots consistent. Different blends and parameters change flavor, so shops tune each variable.

Espresso is the base for many fancy coffee drinks and the core offering that showcases a café's extraction skills. It uses high-pressure hot water to penetrate finely ground coffee in a short time, producing a small cup of highly concentrated, flavor-packed coffee liquid. A qualified Espresso usually has two hallmarks: a golden-brown layer of crema on the surface, and a strong, long-lasting taste impact on the palate. This article focuses on the main characteristics, standard method, and timing parameters of espresso to help enthusiasts understand the extraction logic. At the same time, using a commercial single-group coffee machine as an example, Front Street shares operational details such as dose, yield, and time control, and introduces several Front Street blends suitable for espresso, making it easy for readers to choose based on flavor preference.

In recent years, coffee has become increasingly popular in China, and the number of cafés on street corners has clearly increased. Among them, espresso-based coffee, which focuses on efficiency and convenience, is especially favored by consumers. It is that small cup of rich espresso that lays the flavor foundation for many popular drinks such as Americano, latte, and mocha. Today, Front Street will talk about this espresso, known as the "soul role" in cafés, and what characteristics it actually has.

Core Characteristics of Espresso

Espresso, also called Espresso, is a coffee liquid obtained by Italians using a pressure coffee machine to extract quickly with high-temperature water, and its surface is usually covered with a layer of golden foam. Different shops use different espresso beans and extraction parameters, so the flavor performance also varies. However, a standard-compliant espresso generally has the following two characteristics.

Crema (oil layer)

If you order an espresso in a café and the barista brings it to you right after extraction, you can often see a thick golden foam floating on top of the liquid. This is what we call crema.

Coffee beans generate a large amount of gas during roasting. High-pressure water dissolves out carbon dioxide during extraction, and when the coffee liquid returns to normal pressure, the liquid can no longer retain all the gas, so countless tiny bubbles surge out from the liquid. These bubbles stay on the surface of the coffee, forming a seemingly quite stable "bubble layer." A rich and fine crema shows that the coffee beans used for this espresso were freshly roasted. This is because the gas inside coffee beans continues to be released over time; the farther from the roast date, the less carbon dioxide remains, and the thinner the foam formed during extraction.

If there is no crema at all on the surface of an espresso, the reason may be that the coffee beans were stored too long, or that the espresso sat too long after being made and the foam dissipated. The darker the color of the crema, the more intense the taste often is. This is because the Maillard reaction occurs in coffee beans during high-temperature roasting. The darker the roast level, the darker the foam layer and the more mellow the mouthfeel.

High concentration

A single espresso needs to release a large amount of soluble substances in just a few dozen seconds, so the coffee grounds must be ground extremely fine and evenly. Under the combined action of near-boiling hot water and strong pressure of about 9 atmospheres, espresso is very concentrated, and all flavors are doubled and concentrated, presenting a strong taste impact on the palate. After swallowing, various aromas still linger in the mouth, with a long finish. Because of this, many cafés serve a glass of water alongside a strong espresso.

How to Make Espresso

Many coffee enthusiasts have unknowingly acquired various coffee equipment at home, and friends fascinated by espresso have long since bought espresso machines, planning to extract it themselves. Here, Front Street uses café espresso production as a reference to briefly explain how to make an Espresso.

The coffee machine used in Front Street shops is the commercial single-group "Lelit Bianca," which can adjust extraction by changing pressure, with a maximum pressure of up to 11 bar. As long as a home coffee machine can reach 9 bar pressure, it is enough to complete extraction and steam milk foam, and pairing it with an espresso grinder is all you need.

Front Street uses the capacity of a double basket, with a dose of about 18–20 grams; for production, Front Street takes 20 grams of coffee grounds. The ratio of coffee grounds to coffee liquid is usually controlled between 1:1.5 and 1:2.5. Front Street uses an extraction ratio of 1:2, that is, 20 grams of coffee grounds extract 40 grams of coffee liquid. The extraction time is related to the flow rate of the coffee grounds. Generally, a single extraction is controlled at 20–35 seconds, because within 20 seconds the coffee taste is often thin, while over 35 seconds it is easy to over-extract and produce a burnt bitter taste. Front Street's espresso mostly falls within the range of 28–30 seconds.

Front Street's operation steps are to first wipe the basket dry, turn on the grinder, grind the amount for a double shot, and place it on the electronic scale to increase or decrease until it reaches 20 grams. Then use a tool to distribute the coffee bed evenly, and tamp the coffee puck firmly to ensure more stable extraction. Then turn on the extraction switch to release water, wetting the group head while washing away attached coffee grounds, gently lock the portafilter onto the group head, and flip the switch down to start extraction. When the electronic scale shows the coffee liquid reaches 40 grams and the time is about 30 seconds, you can pull down the extraction switch. Pour the coffee liquid into an Espresso cup and enjoy.

The taste and mouthfeel of Espresso depend on the coffee beans used. The espresso produced in Front Street shops uses Front Street Sunflower Warm Sun Blend . This bean is composed of Front Street Honduras Sherry coffee and Front Street Ethiopia natural Red Cherry in a 7:3 ratio. Made into Espresso, it has rich crema, a very obvious whisky aroma, with vanilla biscuit and berry acidity on the palate , a solid flavor, and after drinking, the whole mouth is filled with various aromas.

Espresso can also be diluted with water, which is the common Americano on the menu, full of delicate fragrance; adding milk turns it into a latte, presenting a sweet, chocolatey, creamy deliciousness.

Espresso Blend Coffee Bean Recommendations

In addition to the whisky-style Front Street Sunflower Warm Sun Blend, Front Street's bean list also has three cost-effective Front Street espresso blend coffee beans to choose from. The espresso they extract mainly presents nutty notes, and each blend has subtle differences due to different proportions.

1. Classic full-bodied type — Front Street Commercial Blend Coffee Beans

Robusta washed coffee beans (10%) + Colombia washed coffee beans (30%) + Brazil semi-washed coffee (60%)

The espresso produced has rich golden crema and obvious nutty aroma. When tasting, you can feel the roasted coffee bitterness, but it is accompanied more by a creamy, full mouthfeel. After swallowing, the bitterness also dissipates, leaving fragrance on the lips and teeth. It is suitable for daily café production.

2. Slightly acidic full-bodied type — the espresso moka pot coffee beans recommended by many baristas - Front Street Dark Cocoa Blend Coffee Beans

Yunnan washed small-bean coffee (30%) + Brazil semi-washed coffee beans (70%)

Yunnan small-bean coffee has a soft acidity, and combined with the mellow aroma of Brazil Cerrado coffee, the espresso presents caramel, nuts, and a soft plum acidity. This cost-effective espresso blend coffee bean is suitable for opening shops and home users who prioritize cost and have average flavor requirements.

3. Balanced rich-aroma type — Front Street Specialty Blend Coffee Beans

Colombia washed coffee beans (30%) + Brazil semi-washed coffee beans (70%)

Adding Colombia coffee to the nutty notes of classic Brazil coffee, the espresso presents a dark chocolate flavor with caramel sweetness and a full roasted aroma, which can meet the daily needs of opening a shop.

Finally, if you want the extracted espresso to present the various flavors described by Front Street, Front Street recommends choosing freshly roasted coffee beans. After roasting, coffee beans need to go through a 7–10 day degassing stage, and then enter the flavor-rich peak period, when the extracted espresso is more stable. To ensure everyone can drink freshly roasted coffee beans after placing an order, the coffee beans shipped by Front Street are all freshly roasted within 5 days, so that when you receive them they are still at the stage of rich aroma.

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The above content is compiled by CoffeeHunters, a coffee news website.