A Guide to Properly Enjoying Italian Espresso: Flavor and Taste Characteristics

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The Birth and Spread of Espresso

Espresso was born around 1946, and this year is considered the official birth year of espresso. Since then, this unique coffee beverage has been popular in southern European countries such as Italy, Spain, and Portugal. However, it wasn't until around 1986 that espresso was promoted worldwide by Starbucks. After that, coffee professionals from around the world began to recognize and understand this type of coffee. This was only about ten years earlier than when Chinese people came into contact with espresso. Therefore, a popular and reasonable naming convention is "Italian-style coffee."

Espresso as a Way of Life

In Italy, espresso is simply the concerto of local life. Upon waking up in the morning, people first drink a latte. Afterward, people like to go to the café to drink espresso. Everyone waits in front of the bar counter, and after getting their fresh coffee, they finish it in three small sips. Customers in the café know each other and chat, even the barista joins the conversation, making the café a social gathering place.

In the United States and Taiwan, Italian-style cafés line the streets and are places where young people meet and chat. Most of them don't drink espresso, only cappuccinos or lattes with milk. These young people mostly don't know the delicious taste of espresso; they just come here to experience the espresso atmosphere. Presumably, this can also be considered a form of espresso life!

The Definition and Characteristics of Italian Espresso

Italian espresso coffee: served in a small, heavy ceramic cup with a capacity of about 50 milliliters, containing a half-full cup of dark coffee with a thick layer of reddish-brown fine foam on the surface. A chemist would not like such a description and would choose less poetic but more precise terms. However, the above definition can completely describe the characteristics of a cup of espresso coffee, at least expressing its main features from a macro perspective:

Small volume: This means the brewed coffee is more concentrated than regular coffee.

Physical composition: The foam part of the coffee is as important as the liquid part.

These characteristics are, of course, the result of using special percolation methods to brew coffee. In the following article, we will describe the characteristics of espresso coffee in detail from a sensory perspective, supported by physical and chemical data.

Sensory Characteristics of Espresso Coffee

The warm tones of the foam, the strong and wonderful aromatic fragrance, the velvet-like soft and smooth liquid, the intense and persistent taste— all these characteristics presented in a well-brewed cup of espresso coffee provide drinkers with pleasure in terms of smell, taste, and sight. Only hearing is excluded from this multi-sensory experience. Between the complex chemical composition of coffee and the multi-layered sensory system, a connection is created by sipping this small cup of coffee.

Visual Characteristics

The most visually striking feature of a cup of espresso coffee is the foam. The beautiful scenery presented by the foam is composed of tiny bubbles trapped in viscous liquid, as well as the tiger-stripe patterns formed on the foam due to floating cell wall fragments.

The color and texture of the foam are very important to espresso coffee drinkers because, for the drinker, perfect foam represents a perfect coffee brewing process. Any errors in grinding, brewing, temperature, or extraction will be immediately reflected in the color, texture, and persistence of the foam. For example, if the foam is thin, light-colored, uneven in texture, and gradually disappears, it indicates that this cup of espresso coffee is under-extracted. This might be due to too coarse grinding particles or too low water temperature. If the foam in the above cases is very dark and has holes in the center, it indicates that the coffee puck's porosity is too low or there's too much coffee powder. The causes of over-extracted espresso coffee include: if due to too high water temperature, the foam will appear white with large bubbles; if due to too long brewing time causing over-extraction, there will be white spots in the center of the foam.

The foam also serves as a seal for the coffee aroma because it can trap the volatile chemical molecules that constitute the coffee aroma. If the bean blend is suitable for brewing espresso coffee, this aroma will be pleasant; otherwise, it will be unpleasant. The foam is an amplifier that equally magnifies both the coffee's strengths and weaknesses.

Mouth Feel

Body is another important characteristic of espresso coffee. The oil droplets in coffee not only dissolve many flavor chemical molecules but also increase the coffee's viscosity. Another form of tactile sensation is astringency, which has always been disliked and associated with medicine. The presence of astringency is related to the presence of immature beans, which contain polyphenolic compounds that cause a bitter and astringent sensation in the oral mucosa and interact with soluble proteins in saliva.

Taste

When appreciating a cup of espresso coffee, sweetness is an important characteristic, but sourness is not. Consumers from different countries show extremely significant differences in their appreciation of the ratio of bitterness to sourness in espresso coffee. Consumers from more southern countries prefer more pronounced bitterness and focus on body expression, while those from more northern countries prefer more balanced taste and consider excessive bitterness a drawback. This difference can also be seen in the concentration differences of espresso coffee. In more southern countries, espresso is small, concentrated, and mostly consumed without milk, while in more northern countries, people prefer more diluted versions and often drink it with milk or cream.

Unfortunately, it's quite difficult to brew a cup of espresso over fifty milliliters without causing over-extraction, which is why most northern espresso tastes woody or astringent. This taste is often described by drinkers as bitterness because when extracting large amounts of coffee, some soluble unpleasant substances are also extracted. The roasting degree of coffee beans can change the ratio of bitterness to sourness in espresso coffee; very dark roasted washed coffee beans will have irritating burnt flavors that are usually disliked. Very fast roasting can cause unpleasant tastes such as astringency, bitterness, and metallic flavors.

Aftertaste

The liquid nature of espresso coffee is quite special. Its high concentration is caused by high density and high viscosity, while on the other hand, the presence of natural surfactants reduces the surface tension of espresso coffee. The existence of these conflicting characteristics explains the unique intense taste of espresso coffee and the persistent post-drinking taste and flavor sensation. When drinking, the tongue surface is bathed in it, allowing the coffee to be captured by taste buds.

At the same time, the oil droplets in espresso coffee attach to the tongue mucosa, slowly releasing volatile aromatic molecules, so these tastes and flavors can still be felt for a period (up to 15 minutes) after drinking the coffee. The phenomenon of the tongue being covered by coffee can explain why bitterness perception is reduced. This can be indirectly confirmed by the following experiment: let a group of subjects first drink a quinine solution and rate the perceived bitterness level as 100, then try drinking a quinine solution with 1% concentration of colloidal polysaccharide (carboxymethylcellulose), at which time the subjects only perceived a bitterness level of 40.

The conclusion of this experiment is that colloids can block the bitterness receptors of taste buds, causing reduced bitterness perception. The emulsified oil droplets in espresso coffee may act similarly to colloids, reducing the perception of bitterness. However, diluted espresso coffee actually increases bitterness perception because it contains billions of bitterness molecules, but the number of oil droplets is only one-thousandth or one-ten-thousandth of that. Therefore, when espresso coffee is diluted, it actually increases the chances of bitterness molecules being captured by receptors, causing the phenomenon that diluted espresso coffee is actually more bitter.

Overall, a good cup of espresso coffee should, in terms of taste, have some sourness at the beginning, followed by alternating bitterness and sweetness. In terms of mouthfeel, it should have a heavy body, in terms of smell, it should have strong aromatic flavors that can be pleasantly sustained for a period of time.

Espresso Coffee Brewing Methods

Whether it's pour-over coffee or espresso coffee, to brew it well, you must use high-quality, freshly roasted coffee beans. FrontStreet Coffee currently sells 4 types of espresso coffee beans, all shipped within 5 days of roasting, ensuring that every customer receives the freshest coffee when they place an order. The coffee bean resting period is about 4-7 days, so when customers receive it, it's at its peak flavor.

"Warm Sun Blend Coffee Beans" consists of Ethiopian natural red cherry coffee beans (30%) + Honduras sherry barrel coffee beans (70%), with rich wine aroma, vanilla cream, berry sweetness and sourness, and roasted nut flavors.

"Specialty Blend Coffee Beans" consists of Colombian washed coffee beans (30%) + Brazilian natural coffee beans (70%), with nut, dark chocolate, and caramel flavors.

"Commercial Blend Coffee Beans" consists of Robusta washed coffee beans (10%) + Colombian washed coffee beans (30%) + Brazilian natural coffee (60%), with nut, cocoa, and caramel flavors.

"Basic Blend Coffee Beans" consists of Yunnan washed small bean coffee beans (30%) + Brazilian natural coffee beans (70%), with gentle fruit acidity, caramel, and nut flavors.

Delicious espresso coffee cannot be separated from grinding and brewing on the spot. Although FrontStreet Coffee provides grinding services, the aroma of coffee dissipates quickly after grinding. Therefore, to taste better espresso coffee, FrontStreet Coffee suggests customers buy whole beans and grind them before extraction.

According to the Specialty Coffee Association (SCA) standards, single espresso uses 7-9 grams, double espresso uses 14-18 grams of coffee grounds to extract 25-35g of coffee liquid in 20-30 seconds, with extraction pressure at 9-10 bar and water temperature at 90-96°C. Each coffee shop makes adjustments up and down according to the coffee beans and equipment used.

FrontStreet Coffee uses its own sunflower warm sun blend, which has gentle fruit acidity and charming fermented wine aroma, so the extraction water temperature is set at 94 degrees Celsius, and extraction pressure is controlled at 10 Bar.

The Art and Science of Espresso

The sensory characteristics of a cup of espresso coffee should include: heavy body, rich fine crema, balanced bitterness/sweetness ratio with sourness, pleasant and persistent aftertaste, and no unpleasant flavors or defects.

Humans are not simple organisms that can be described purely in scientific terms; they are more complex beings. Many of the conditions we use to appreciate espresso coffee cannot yet be explained, so the current definitions proposed about espresso coffee cannot include everyone's insights and judgments. Therefore, in the world of espresso coffee, a line must be drawn between objectively analyzable science and art. Art is subjective, belonging to personal creativity or passion for coffee. Although art is not yet a science, with enough time and effort, it can develop into knowledge and gradually form a skill, ultimately achieving the same status as science.

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