How the Coffee Flavor Wheel Organizes Aroma and Taste

The coffee flavor wheel, developed by the SCAA together with several universities, gives tasters a shared vocabulary for describing what they smell and taste. It organizes roughly 85 flavors into nine major categories, covering floral, fruity, nutty, cocoa, spicy and fermented notes that develop during roasting and processing.

Roasted coffee beans contain about 1,200 compounds, compared with more than 300 in chocolate and roughly 150 to 500 in wine. Those compounds create the coffee aroma people notice first, and the number of aromatic substances is said to run into the thousands. Long-term drinking builds the ability to separate the layers.

Every cup of coffee contains thousands of aromatic compounds, and these substances interweave into a complex and captivating flavor profile. The coffee flavor wheel, developed by the SCAA (Specialty Coffee Association of America) in collaboration with several universities, provides tasters with a systematic descriptive language. This article will guide you through the sources and composition of coffee flavors, explain the meanings of the nine major categories and approximately eighty-five flavors in the flavor wheel, and describe how floral, fruity, nutty, cocoa, spicy, and fermented flavors form during roasting and processing. We will also introduce the flavor characteristics of specific coffees such as Front Street Yirgacheffe, Front Street Geisha, and Front Street Mandheling, helping you more accurately identify and express coffee flavors in daily life.

When drinking coffee, the aroma that greets the nose always captures attention first. Those with some knowledge of coffee can name the specific types of aroma, while those new to coffee often just call it "coffee aroma" in a general way. In fact, there are so many kinds of aromatic substances in coffee that no one has yet been able to give an exact total—because the number of aromatic factors is truly inexhaustible, said to be as many as a thousand. These odors make up the coffee aroma we smell; some are abstract, some concrete, some bold, some understated. Whether you can distinguish them is simply a matter of accumulated time. After drinking coffee for a long time, you will naturally be able to identify different layers of aroma.

So what exactly do coffee flavors refer to?

Roasted coffee beans contain about 1,200 compounds, and it is these substances that give coffee its rich taste and olfactory experience. Bitterness is only a small part of it.

How rich are 1,200 compounds? Let's compare with the familiar chocolate and wine:

Chocolate: contains more than 300 compounds.

Wine: contains 150 to more than 500 compounds, already enough to fascinate enthusiasts with the surprises brought by different varieties.

Coffee's more than 1,200 compounds are four times those of chocolate and more than twice those of wine.

Besides bitterness, what other flavors does coffee actually have?

Broadly speaking, flavors can be divided into the following nine major categories, totaling about eighty-five kinds.

These eighty-five flavors were derived from collaborative research by the SCAA (Specialty Coffee Association of America) with Kansas State University and Texas A&M University. The original intention was to provide a unified and quantified descriptive language for coffee tasting, so that the flavors of different coffee varieties could be evaluated more scientifically and comparably.

Friends who love specialty coffee should be familiar with this SCAA flavor wheel, but many people say they do not quite understand it. Today, let's briefly talk about the structure of the flavor wheel and what it expresses.

Classification of coffee flavors and aromas and the reasons for their formation

Enzymatic fermentation: This is the flavor produced by fermentation during green bean processing (such as washed, natural, and honey processing), such as floral and fruity notes.

Sugar browning reaction: This is the flavor produced by caramelization and the Maillard reaction during coffee roasting, such as nuts and chocolate.

Dry distillation reaction: This is the flavor produced by dry distillation during roasting, such as the taste of currants and smoke.

There is a saying that "the flavor wheel from top to bottom also represents the flavors produced by different roasting degrees of coffee," but in fact dry distillation reactions begin as soon as roasting starts, so this saying is not very accurate.

In terms of taste, it is divided into different sensory categories such as sour, sweet, bitter, and salty. It is said that umami will be added to the flavor wheel in the future.

Improper handling during the harvesting and drying stage of coffee can produce defective flavors, and aging during storage can also bring some unpleasant tastes.

If the coffee is not processed in time after harvesting, or if the humidity and temperature during drying are unreasonable, fermentation will produce Rio flavor, fermented flavor, and so on. If the temperature is too high during drying and the coffee beans are heated too quickly, the oils will break down and produce flavors such as leather.

After green bean processing is completed, reactions continue internally during storage, and organic substances gradually change and are lost. New beans have a grassy flavor, and after several years of storage, as organic substances are lost, they turn into straw and wood flavors; at this point the coffee already tastes very dull.

Coffee flavors are actually complex and multi-layered.

1) Floral and fruity aromas

When lightly roasting coffee beans, highly volatile molecules are released first, and one of them is floral and fruity aroma.

In the flavor wheel, floral and fruity aromas are two separate categories.

Floral: a light, slightly sweet, elegant fragrance.

Fruity: a slightly sweet mixed aroma among various ripe fruits, with fruity floral notes.

In specialty coffee, floral aromas are relatively rare.

1. "Yirgacheffe" from the Ethiopian region

2. Sidamo region

3. Panama's "Geisha"

All have enchanting floral aromas, resembling jasmine and passion fruit.

In Front Street Yirgacheffe, citrus is the most prominent among the fruity notes.

Front Street Geisha can be called the king of coffee orange aroma. After the roasted beans have rested for a few days, when you open the bag, the orange and lemon aromas rush out. Its pronunciation is very similar to the English and Japanese word for "geisha," so it is also called "Geisha."

In addition, Front Street Kenya's national treasure varieties "S28" and "S34" carry the sweet, tart aromas of smoked plum and berries among fruity notes.

2) Green/vegetative

Starting from this category, the flavors need a little explanation.

Raw: ingredients that have not been cooked or prepared, such as the natural feeling of raw sunflower seeds or raw beans.

Unripe: fruit that is not yet ripe on the tree, with a taste similar to grapefruit peel.

Fresh: the smell of freshly cut grass.

Dark green: cooked green vegetables, such as the canned spinach that instantly transforms Popeye.

Vegetative: the slightly pungent taste of green vegetables; the reference given is canned asparagus.

Spice leaves: such as bay leaf, basil, and thyme.

Beany: the flavor of beans and bean products. Although aromatic acids in the sour category are also beans, that one focuses more on sourness.

Among single-origin coffees, Indonesia's Lake Toba Lintong region "Front Street Mandheling," after medium-dark roasting, sometimes still has a scent of grass jelly, which is quite unique.

Indonesia Lake Toba Lintong

3) Nutty/cocoa

Produced in coffee beans after medium roasting due to the Maillard reaction. This aroma is relatively common and includes:

Nutty: roasted almonds, roasted peanuts, roasted hazelnuts, walnuts.

Cocoa: dark chocolate.

4) Sweet

During medium roasting, sour aromas break down, and caramel aroma is produced by sugar browning through caramelization. It includes:

Vanillin: although it is also vanilla, it differs from the vanilla category that emphasizes vanilla pod aroma; vanillin mainly refers to a chemical vanilla flavor, such as vanilla marshmallows.

Chemical sweet: similarly, refers to the sweetness of chemical agents.

5) Spices

Generally produced during dark roasting, including:

Pungent: a sharp, nose-tingling taste; the reference given is a kind of orange essential oil.

6) Sour/fermented

Aromatic acids: acidic products, such as a kind of canned pinto beans.

Citric acid and malic acid: focus more on sourness and astringency, and are stronger.

Butyric acid: the taste of certain aged cheeses, such as Parmesan.

Isovaleric acid: also the taste of certain aged cheeses, such as Romano.

Among single-origin coffees, Indonesia's "Mandheling," because of its unique wet-hulling method, greatly shortens drying time and creates a unique regional taste of low acidity and muted aroma.

Under 6) Alcohol/fermented subcategories:

Overripe: although the reference is banana, it also refers to the sweet, slightly sour, moist, moldy, or earthy taste of other overripe fruits or vegetables.

Wine: the reference is Yellow Tail Cabernet Sauvignon.

Whiskey: the reference is Jack Daniel's Tennessee Whiskey Old No. 7.

Fermented: the reference is Guinness Extra Stout.

Among single-origin coffees, naturally processed beans more or less have a vinous aroma. Among them, the editor's favorites are Front Street Natural Yirgacheffe and Front Street Winey Natural Guatemala.

Bitterness: specifically refers to the bitterness after charring. The bitterness usually tasted is the bitterness of caffeine, not necessarily the kind of bitterness after charring.

Dusty: the smell of paper ash after burning paper.

Smoky: the smell of wood ash after burning wood.

Brown, roast: purely refers to the feeling of having been roasted.

Toast: this is one of the subtle aromas that roasters work hardest to achieve, and it is also a sign of skillful roasting. If the coffee is roasted one second too long, this full and delicate aroma will be lost and replaced by other more aggressive tastes.

8) Other

Stale: lacking a fresh feeling, the taste of fermented bread or expired bread.

Musty/moldy: the damp smell of a basement.

Moldy/dusty: wheat germ, similar to the taste of cereal crumbs.

Phenolic: this is not a misplaced image, nor a still from Fifty Shades of Grey. This is an old-fashioned tack room, a damp space with an animal smell.

Among these, woody aroma is produced by dry distillation during dark roasting. This flavor receives mixed reviews: those who like it enjoy the woody charm in coffee, while those who do not feel it affects the coffee's own flavor.

Coffee beans with woody charm include:

1. Colombia "Huila"

2. El Salvador's national treasure variety "Pacamara"

3. Hawaii "Kona"

4. Estate beans from Honduras

5. Panama Elida Estate

Most of these varieties form unique aromas because the estates growing the coffee happen to also have pine, fir, or other trees.

Most of these flavor descriptions are based on Western taste experience, such as cheese, nutmeg, and skunk.

After saying so much, do you understand coffee flavors now? It turns out that a tiny coffee bean can actually contain so many aromatic factors, and these aromas are what people commonly call coffee flavors. So how can so many coffee aromas be distinguished? As the saying goes, practice makes perfect. A person who often drinks coffee and understands coffee can naturally explain the reasons. So if you meet someone who can describe various coffee flavors, do not be surprised; he may just be a coffee enthusiast, or he may even be a barista himself.

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