Why Does Coffee Aroma Matter More Than Taste Buds in Tasting?

Identifying coffee flavors depends mainly on smell, not taste buds. Taste buds perceive only five basic tastes, and coffee has no umami while saltiness is masked by sourness and sweetness. The tongue registers sour and sweet first and bitterness later. True flavor recognition happens through orthonasal and retronasal olfaction, since the throat and nasal cavity are connected.

Beginners can train this sense deliberately. Useful methods include building a flavor memory bank, using the coffee flavor wheel, practicing associative thinking, learning through conversation with other drinkers, and paying attention to diet and rest. Working through aroma, sweetness, acidity, mouthfeel, flavor, aftertaste, and balance builds a personal sensory system step by step.

People new to specialty coffee are often puzzled: why can others taste citrus, jasmine, oolong tea? Can a cup of coffee really have so many flavors? In fact, the key to identifying coffee flavors lies not in the taste buds, but in the sense of smell. This article will take you from the principles of sensory perception to understand how taste buds work together with orthonasal and retronasal olfaction, recognize tasting dimensions such as aroma, sweetness, acidity, mouthfeel, flavor, aftertaste, and balance, and provide beginner-friendly sensory training methods—building a flavor memory bank, making good use of the coffee flavor wheel, exercising associative thinking, accumulating through communication, and paying attention to diet and maintenance. The article also combines examples from Front Street Coffee to help you build your own sensory system step by step.

"This bean has a very fruity character—you can taste citrus, lemon, oolong tea, and jasmine!"—For friends just getting into specialty coffee, this kind of description sounds like a fairy tale: it's just a cup of coffee, how can you taste so many things? Is this just making things up? In this installment of Barista Development Diary, let's talk about a beginner's real process of sensory training.

Are coffee flavors tasted by the taste buds?

No, it needs a partner—the sense of smell～

That's right, coffee flavors cannot be fully perceived by the taste buds alone, and when it comes to identifying flavors, the taste buds actually play a supporting role. Our taste buds can only perceive 5 basic taste substances—sour, sweet, bitter, salty, and umami—and coffee has no "umami" taste, while saltiness is normally completely masked by sourness and sweetness.

I wonder if you've noticed that when taking the first sip of coffee, we first perceive the sour and sweet tastes, and only then the bitterness. That's because the tongue also has its own "workflow" for distinguishing tastes. The tip of the tongue perceives sourness, the sides of the tongue near the tip perceive saltiness, the sides of the tongue near the base perceive sourness, and the base of the tongue perceives bitterness.

Truly identifying flavors still depends on the sense of smell. (Can we still smell food after it enters the mouth?) Yes! The throat and nasal cavity are interconnected. After coffee is brewed, some flavor molecules are wrapped in oils, and at this point we cannot clearly perceive them by smelling directly. When these aroma-wrapped oils enter the oral cavity, the taste buds first judge the taste of the coffee, and then the oils melt on the tongue, releasing aroma. These aromas "sneak" into the nasal cavity during swallowing; this is called retronasal olfaction, while what we can directly use to judge smell is orthonasal olfaction.

When our taste buds perceive taste plus our sense of smell perceives aroma, our brain associates them with specific objects. So why can some people associate a specific object while others cannot? This has to do with one's own flavor memory. Moreover, coffee flavor itself is a very general definition. For example 🌰: the acidity in a cup of coffee may remind one person of lemon, another of pomelo, and so on—all very normal. The fun of tasting coffee lies in sharing and discussing with those around you after you perceive a flavor.

From what angles do we discuss coffee flavor?

Aroma, sweetness, acidity, mouthfeel, flavor, aftertaste, balance

"Aroma"—orthonasal olfaction

Coffee aroma is divided into dry aroma and wet aroma. Dry aroma refers to the aroma released when coffee beans are ground into particles in a dry state; wet aroma refers to the aroma released by the coffee liquid extracted from coffee particles with water. The dry and wet aromas of the same coffee bean can differ, because many specific aroma molecules require a certain temperature to volatilize. For example, when a barista at Front Street Coffee smelled the Green Label Geisha from Hacienda La Esmeralda, the dry aroma had a fresh sugarcane note, while the wet aroma had the fragrance of ginger flower.

"Cleanliness"—retronasal olfaction

Cleanliness refers to coffee having no defective or unpleasant flavors. For example, some lower-quality coffee beans may have an earthy/woody taste after brewing, or other unpleasant off-flavors.

"Sweetness"—taste buds

Sweetness refers to the sensation of taste. A cup of coffee with good sweetness can improve people's evaluation of it. Of course, this sweetness is not as obvious as sucrose; in many cases sweetness is expressed in the sweet aftertaste.

"Acidity"—taste buds

Whether coffee's acidity is strong can be distinguished by how much saliva is secreted on both sides of the tongue; the stronger the acidity, the more saliva is secreted. The acidity in good-quality coffee generally tends toward fruity acidity (fresh, gentle sourness), while some poor-quality coffee may show acetic acidity (strong, pungent sourness).

"Mouthfeel"—oral touch

Coffee's body/smoothness/astringency are all perceived through oral touch. Body can be described as light-full-solid. This feeling is like drinking skim milk-whole milk-cream; your tongue will feel different degrees of "tongue pressure." Astringency is the rough tactile sensation produced by polyphenolic compounds in coffee, opposite to smoothness. The appearance of astringency directly lowers your evaluation of a cup of coffee.

"Flavor, aftertaste"—taste buds + retronasal olfaction

Flavor refers to our overall impression of drinking the coffee, combining various sensations produced by smell and taste. This requires combining one's own memory of tastes, and then whether one can associate them after drinking the coffee. Aftertaste refers to the various tastes and aromas remaining in the oral cavity after drinking coffee. If a pleasant flavor can linger in the nasal cavity for a long time, we can describe the coffee as having a long aftertaste. Just like the Green Label Geisha mentioned above from Front Street, the aftertaste it shows after drinking is a light floral note and green tea aroma.

"Balance"—taste buds

Balance refers to whether the various indicators of the coffee are well balanced, for example whether it is too sour or whether bitterness is particularly prominent.

How can beginners scientifically develop their own sensory flavor descriptions?

Build a flavor memory bank

For those just getting into coffee, you cannot understand why a barista can blurt out what flavor a coffee has. In fact, if you look at it from another angle, you'll find it quite normal [when you usually eat rice, if you eat the same rice every day and suddenly one day switch to another rice, you can clearly feel the difference]. This skill is innate, but being able to say "what exactly is different" requires constant accumulation and training.

Therefore, to quickly taste coffee flavors, you must first taste or smell the actual objects described by the coffee's flavors and build your own sensory memory. Otherwise, when someone says this coffee has a strawberry flavor, if you have never even tasted a strawberry, how can you know what flavor it is! The coffee flavor wheel published by the SCAA is a very good reference object; you can try to experience one by one the actual objects described on the coffee flavor wheel.

Build your own sensory system

In flavor description and communication, we need to reach consensus. The scientific aspect of the coffee flavor wheel is that it categorizes many flavors. For example, citric acid and acetic acid are classified as acidity, lemon and citrus as citrus fruits, while berries, apples, peaches, etc. are classified as other fruits, honey, caramel, maple syrup, etc. as brown sugar types, and chocolate, almonds, walnuts, hazelnuts, etc. as nut and cocoa types. And the entire flavor wheel goes from green herbaceous plants to yellow fermented acidity to red fruits, then pink flowers, orange sugars, and brown nut and cocoa types. All of these reflect the main ranges of coffee flavors expressed by different roast levels.

For example, light-roasted coffee will be concentrated in acidic fermentation, fruits, and flowers. Medium-roasted coffee will be concentrated in sugars, flowers, berries, and dried fruits. Dark-roasted coffee will be concentrated in brown sugar, nuts and cocoa, and spices. The flavor wheel can help you build connections between real objects and coffee in a more systematic way.

Some imagination is needed

You need to know that a cup of coffee cannot be 100% that flavor. For example, describing it as citrus flavor does not mean it is percent citrus flavor, otherwise it would become a cup of citrus juice. For example, when we taste a cup of Yirgacheffe [a rush of aroma comes forward, with some floral notes mixed with berry notes, and the acidity tastes like eating citrus, the sweetness like honey, and the aftertaste like the feeling after drinking green tea.] These are not a 100% match, but at least there is a feeling of about 70%-80% similarity.

Communicate more and accumulate often

In daily life, you can communicate more with the outside world to help calibrate your senses. Dare to express the flavors you perceive; everyone's expression of things will differ because they are in different environments and have different experiences. For example, red currant is often used abroad to describe coffee flavor, which is very unfamiliar in China. Besides communication, you also need to keep accumulating to enrich your flavor memory bank.

Pay attention to your diet in daily life

Maintaining your taste buds is the foundation. Eating less spicy and other stimulating foods and drinking less alcohol can keep your taste buds active and allow you to perceive more flavors.

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