Since 1995, the Specialty Coffee Association of America (SCAA) Coffee Taster’s Flavour Wheel has been the industry standard for coffee professionals all over the world. The illustrative coffee wheel, produced in collaboration with SCAA and the World Coffee Research, boasts a comprehensive list of descriptive terms that reflect the standards of specialty coffee at that time.
But over the past two decades, climate change has forced coffee growers to cultivate an increasing number of drought- and disease-resistant varieties, prompting sensory professionals to adopt a more descriptive approach to define coffee flavour. The wheel received its first update in 2016, drawing on research compiled by dozens of sensory scientists at the Sensory Analysis Centre. Today, it is the single most comprehensive piece of research on coffee flavour.
The revamped wheel goes beyond cupping among coffee roasters and baristas. It is also a valuable tool for casual coffee drinkers who seek to discern good coffee from bad.
We’ve created abridged versions – the Aroma Wheel and Taste Wheel. Think of them as dictionaries to refine your perception of taste and broaden the vocabulary you use to describe coffee.
Navigating Through the Taste Wheel and Aroma Wheel
A coffee’s flavour is a combination of chemical components perceived by the taste buds, and aromatics perceived by the nose. Other than the sweet, salty, bitter and sour taste attributes, the coffee aroma is said to be the most important attribute to coffee tasting.
Both aroma and taste profiling is essential to understanding and appreciating coffee. The key is to observe them at different stages. Read on to learn how to use the wheels.
Step 1: Smell Some Coffee
Pay attention to the aromas of freshly ground beans as they will tell you a lot about the coffee’s freshness and personality. Next, prepare some fresh coffee and take a whiff of the aroma as the coffee is brewing.
Step 2: Familiarise Yourself with the Aroma and Taste Wheel
You might see some unfamiliar words but don’t worry about it at this stage. For now, immerse yourself in the colourful wheels.
Step 3: Start at the Centre
Begin at the centre of the Aroma Wheel and work outwards from the general descriptors. You will find the descriptors becoming more specific as you move towards the edge of the wheel.
Step 4: Taste Your Coffee
Now, take a sip of coffee and consider the flavours you are tasting. This time, turn to the Flavour Wheel and begin once more at the centre. As with the Aroma Wheel, the taste descriptors get more specific as you work your outwards.
As an example: a coffee taster might detect hints of berries. Moving through the ‘sweet’ section, you are confronted with a choice: is it ‘acidic’ or ‘mellow’? If you decide ‘mellow’, sharpen your observations further – is it ‘mild’ or ‘delicate’?
A Trio of Aromas
There is a common misperception that the tongue recognises complex flavours; in fact, that’s the nose’s job. The aroma can be sensed in two ways: nasally (smelling the coffee), or retro-nasally (when coffee is consumed, and volatile aromatic compounds drift upward into the nasal passage).
It is said that there are over 800 aromatic compounds found in coffee. Recent research has narrowed these into three broad categories.
The most pleasant, enzymatic aromas are by-products of active chemical reactions that take place when the pH level in the coffee bean plant is between 5.0 and 7.0. They give rise to the “fruity”, “floral” and “herby” characteristics of coffee.
Sugar Browning Aromas
This category of aromas is most sought after by roasters, which create the chocolatey, caramelly, and nutty characteristics of coffee. As the name implies, the aromatic compounds are released in two stages: the Maillard Reaction and Caramelisation.
At temperatures from 150 to 200 degrees Celsius, carbonyl groups (from sugars) and amino groups react to release hundreds of aromas and flavour compounds, called the Maillard Reaction.
At 170 to 200 to degrees Celsius, the sugars in coffee start to caramelise (brown) and deeper flavours develop. Most of the sugars are converted to caramelised compounds through caramelisation.
During the roasting process, fibrous bean materials within the coffee bean cells begin to burn, releasing “carbony”, “spicy” and “resinous” aromas. Many consider these aromas unpleasant and undesirable although they are sometimes crafted for a unique clove-like and leathery smell.
Aromas enhance our coffee sensory experience, and our ability to smell greatly impacts our sense of taste. To fully appreciate the aromas of your coffee, we recommend that you buy freshly roasted coffee in small amounts frequently, and only grind your coffee beans just before you brew them.
Improve Your Taste Palate
Taste is the sensation perceived on the tongue by the taste buds. The innermost tier of the taste wheel breaks it down into four basic tastes: sour, sweet, salty and bitter.
A sour flavour should not be thought of as a positive or negative attribute. In the coffee world, it is sometimes perceived as a desirable characteristic of fine coffee. The mild or biting sharp sensation you sometimes feel on the sides of your tongue arise from acidic compounds created by under-extraction during the brewing process. This results in a tart and often weak flavour.
On the other hand, coffee that is over extracted tends to taste bitter. Factors that may account for that bitter cup includes over-steeping or a coarse grind. It is worthwhile to note that bitterness is an omnipresent quality of the beverage, and therefore indispensable to coffee’s flavour. Bitterness at low levels can mellow coffee acidity and add an interesting character to the brew. However, too much bitterness can overpower the other components present in coffee, producing an unappealing flavour.
Sweetness in coffee is closely related to the ripeness of coffee cherries, which contain natural sugars when harvested. The sweet quality is usually a good indication that the coffee has been cared for through every stage – from washing to drying and roasting to storing. The term “sweet” is also used by professionals to describe the intensity of sugary qualities in a particular coffee.
Saltiness is considered a taste defect by coffee experts. This brackish quality is usually undesirable and is an indication of inorganic materials or contaminated mineral content that remain in the coffee.
Apart from the sour, bitter, sweet, and salty attributes, there are other dimensions of taste that you won’t find in this wheel.
For instance, the body or mouth-feel of a coffee is viscosity and texture near the back of your tongue that is caused by insoluble protein molecules and oils that remain undissolved in your brew. It can range from light and thin to heavy or full. A full-bodied coffee has a lingering heavy taste, while a coffee lacking body is thin and watery. Colombian and Sumatran coffee beans are well-known full-bodied roasts.
Coffee Tasting is an Art
You will often find that many flavour profiles tend to overlap. Like wine appreciation, it takes practice to develop a nuanced palate for coffee. You have to “train” your taste buds and nose through some exercises so they can learn to distinguish between different tastes and aromas. With a little effort each day, you will be able to achieve a deeper appreciation of your fresh brew.