The Origin of Coffee Flavors: Why Coffee Beans Have Various Tastes and Their Characteristics

When we drink coffee, we often mention that this cup has a nice citrus and juice flavor, while that cup has a rich chocolate and cream taste. Have you ever wondered, while tasting coffee, where these flavors come from?

When we drink pour-over coffee today, we emphasize the origin of the coffee. Just as customers who visit FrontStreet Coffee, FrontStreet Coffee will first ask customers, "What flavor of coffee do you like?" or "Which country (region) of coffee do you usually drink?" This is because different coffee producing countries (regions) have different flavor characteristics, which is what FrontStreet Coffee often refers to as regional flavors. This aligns with the concept of specialty coffee, which proposes that coffee possesses regional flavor attributes.

Regional Flavors

There's an ancient saying, "When oranges grow south of the Huai River, they are oranges; when grown north of the river, they become bitter citrus." This illustrates that even when planting the same plant, the taste of the fruit varies when grown in different places. Coffee is similar, influenced by agricultural and geographical factors such as soil, altitude, variety, and cultivation methods. Each producing region has distinct coffee flavor characteristics.

A classic example is Geisha coffee. We all know that Geisha coffee gained worldwide fame from Panama. Later, we learned that Panama's Geisha traces back to Ethiopia. FrontStreet Coffee won't go that far back, but let's talk about Costa Rica - Panama's Geisha was introduced from Costa Rica. These two countries are closely neighboring. After Panama's Geisha became famous, Costa Rican coffee farmers also began to value Geisha. Today, we can easily buy both Costa Rican and Panamanian Geisha coffee on the market. Interested friends might want to purchase both for comparison. This will help you understand how (micro)climate, altitude, soil, and cultivation methods affect coffee flavors.

Coffee Varieties

In the past, when discussing coffee, we talked about where the coffee was good. Like Santos coffee, Blue Mountain coffee, Yirgacheffe coffee, and Kenya coffee - all are identified by their place names, which confirms what FrontStreet Coffee mentioned earlier about regional flavors. Coffee varieties weren't unimportant, but at that time, farmers in producing regions considered more than just flavor when selecting varieties - they also considered disease resistance, pest resistance, and yield. So although the varieties had different names, the flavor differences between coffee varieties weren't significant. For example, Typica, Bourbon, Caturra, and Catuai have original variety and variant relationships, with differences in flavor but not dramatically so.

Agricultural departments in major coffee-producing countries have always been researching and selecting coffee varieties, aiming to find varieties with good flavor, high yield, and strong disease and pest resistance. They discovered varieties like Geisha, making everyone realize that there are coffee varieties with such amazing flavors. This led to increased exploration for even more delicious coffee varieties, such as the recent competition center-stage varieties like Eugenioides (parent variety), Pacamara, Wush Wush, and so on.

Meanwhile, coffee research institutions in various countries have also tried to use artificial hybridization to select high-yield, disease-resistant coffee varieties, but the flavor performance of these varieties is somewhat inferior.

Processing Methods

Originally, changes in coffee processing were purely to improve efficiency and quality. For example, the washed processing method that appeared in the 18th century was a new processing method compared to traditional natural processing, with overwhelming advantages in efficiency and quality. At that time, natural processing was crude - simply spreading coffee cherries on the ground to dry. Affected by weather and soil microorganisms, moldy and rotten beans were common. The quality was poor, and it was time-consuming (natural processing takes 3-5 weeks).

Later, washed processing removed the skin, pulp, and mucilage before drying, shortening the drying time, improving efficiency, and enhancing quality, though it consumes more water. Brazil's pulped natural processing and Costa Rica's honey processing are also localized methods to improve quality and efficiency. It can be understood that when coffee quality improves, the taste becomes better.

Later, as specialty coffee became popular and flavor became more important, it was discovered that coffee beans from the same region show different flavor characteristics when processed using natural versus washed methods. Natural processing involves more fermenting materials (the entire fruit), resulting in sweeter, richer flavors with heavier fermentation notes. Washed processing, where only the coffee bean participates in fermentation, produces more pronounced acidity, with clean and bright flavors.

Furthermore, the reason natural processing previously had poor quality was because it was too primitive. Using raised drying beds to separate from soil contamination, frequently turning to avoid over-fermentation and mold at the bottom, and using dryers during rainy weather - with this series of measures, high-quality natural coffee can be produced, naturally revealing its sweet, full-bodied flavors.

Today, more and more coffee estates are researching the use of anaerobic fermentation and enzyme addition to enrich coffee flavors, which is another important factor in how processing methods contribute to flavor formation.

Roasting

Everything FrontStreet Coffee mentioned above is about how coffee beans "accumulate flavors," while roasting is what reveals the flavors of coffee beans. The aromatic compounds in green coffee beans begin to undergo complex degradation and polymerization reactions when heated to a certain degree, deriving more abundant volatile aromatic compounds. This is mainly thanks to the Maillard reaction and caramelization reaction.

The Maillard reaction runs through almost the entire roasting process. Under continuous heating, the amino acids that make up proteins in green beans, along with reducing sugars like glucose, fructose, and lactose, undergo complex degradation and polymerization reactions, producing aromatic substances and compounds. This process repeats continuously during heating, like a snowball rolling downhill, generating more and more aromatic compounds.

During this process, over 600 volatile aromatic compounds are produced in coffee beans. As the reaction time increases, fresh floral and fruity aromas first emerge, then develop into deeper-toned flower and fruit scents, followed by more nutty, vanilla, creamy, and caramel notes, though the earlier floral and fruit aromas begin to weaken.

The caramelization reaction occurs after the first crack, as sugars undergo browning, producing aromatic substances like diacetyl (source of creamy aroma), furan compounds (source of caramel aroma), and hydroxymethylfurfural (source of honey and juice aromas)... But excessive caramelization will develop into carbonization, significantly increasing bitter and burnt flavors.

If this is confusing, don't worry. FrontStreet Coffee will explain in simpler terms: during coffee roasting, it's now generally accepted that the defining boundary of "done" is the "first crack." The coffee can be taken out at any time after the first crack. The earlier it's removed, the lighter the roast level, and the more obvious the fruit acidity and floral aromas; the later it's removed, the deeper the roast degree, and the stronger the roasting flavor, with nutty, chocolate, and caramel notes, and a fuller body.

Brewing

Brewing is the final step in flavor expression. In the process of coffee from selection, cultivation, processing, roasting, to brewing, the earlier stages have a greater impact on coffee flavor, while brewing, being downstream, has relatively minimal influence on coffee flavor.

The potential flavor floor of coffee beans is determined by variety, cultivation, and processing. Higher quality coffee beans naturally have a higher flavor floor. Roasting determines whether this cup of coffee will be acidic or bitter, something that brewing cannot change.

However, brewing can adjust the coffee's orientation. For example, with the same acidic coffee, different brewing parameters can produce one cup with bright acidity and another cup with juice-like sweet and sour notes.

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