How we perceive the taste and aroma of coffee

Personal coffee taste profile

The difference of opinion lies in individual taste perception, which is a multisensory experience. Perceived taste is the result of a complex combination of signals travelling to the brain through three sensory pathways:

  • basic tastes: sensations in the mouth caused by non-volatile components
  • smells: mixtures of volatile chemicals perceived through the nose and mouth
  • chemical sensations: warmth or texture as a result of substances stimulating the trigeminal nerve endings in the mouth

What is the aroma and what is the taste of coffee?

Does the distinction between taste and smell seem like an easy question? With coffee, which contains thousands of chemical components, it's a little more complicated. That's why I'm going to give you an example of perceiving flavours and aromas on a scoop of vanilla ice cream.

So how does vanilla ice cream taste to you? The answer is "like vanilla". I'm going to disabuse you of the misconception. Ice cream contains vanilla flavouring. We perceive it through the retronasal system - the area behind the nasal cavity. We perceive the smell ofvanilla as a taste. Therefore, we can say that we smell it not only through the nose (orthonasal system) but also through the mouth (retronasal).

Taste receptors not only on the tongue

The definition of taste, then, is what we perceive in the mouth, using taste receptors. These are located primarily on the tongue but also on the palate and back of the throat. If you have been cupping, you may have noticed that coffee professionals sip coffee samples from a cupping spoon. And they sip loudly.

Along with thecoffee, they also draw air into their mouths as they sip. This causes the coffee to splash all over the mouth. In this way, all taste receptors - not just those on the tongue - have the opportunity to participate in the coffee tasting experience. The taste receptors then distinguish between bitter, sweet, sour, salty and umami.

ⓘ What is the umami taste?

The fifth taste. The taste receptor for umami wasn't discovered until 2000. It is another ability to perceive the spectrum of flavors of commonly consumed glutamate-rich foods (cheese, meat,...).

Somatosensory perception of taste

A part of the trigeminal nerve, leading to the oral cavity, among other things, is stimulated when drinking coffee, causing astringent, spicy, pungent sensations. It also gives the sensation of heat or cold.

Flavours and aromas. How do they work?

Tastes in coffee as an impression of multiple senses

Let's summarize. The recognition of coffee flavours involves the aroma received orthonasally or by the olfactory cells of the nose. At the same time, the retronasal system of the nasal cavity contributes to the perception of smell. In the oral cavity, taste receptors detect bitterness, sweetness, sourness, saltiness and umami. To this is added the trigeminal nerve. But that's not all.

Sight, hearing and coffee flavors

Theaforementioned combination of senses to define the overall perceived flavor of coffee is complemented by sight, hearing and even mood. The atmosphere in which you drink your coffee, the lighting or the colour of thecoffee packaging can all influence how your coffee tastes.

Think, for example, of the use of colour in psychology. With a good mood, you are also more likely to rate the coffee in your cup much better. After all, the sounds, noise or music you hear while drinking coffee corrects your judgement.

When coffee tastes sour or bitter

What happens in your mouth when you drink coffee? The non-volatile compounds in coffee are detected by the taste receptors, which send a signal to your brain. When you taste coffee with a higher acidity (sourness), the coffee acids reach the acidity receptor in your mouth. This sends a signal and your brain processes the information that you are drinking something sour.

Taste receptors recognize not justa type of acidity or bitterness, but a specific taste. Again, I'll take vanilla to illustrate. The pathway of vanilla flavor recognition would be: vanilla flavor molecule - receptor - signal to the brain "you smell vanilla!".

Molecules of chemical compounds (flavors, aromas) bind to receptors like a key fits into a lock. The moment thetaste and the receptor interact, a chain reaction is set in motion to transmit the taste information to the brain.

The complex task of tasting coffee for Q Grader

With coffee, it's not as simple as with vanilla. A single sip of coffee contains a collection of molecules with unique flavors and aromas. That's why coffee tasting is a very sophisticated discipline. It takes a lot of practice to achieve the best results.

The most trained of all among coffee experts, after passing the necessary tests, earn the rank of Q Grader. Such a professional taster can decipher anddescribethe complex flavours in coffeein concrete terms. The task is made more difficult not only by mixing the flavours together, but also by their interplay and overlap.

The development of coffee flavours during the tasting

The complex combination of flavours in a cup of coffee also emerges gradually over the tasting period. For example , theNCArecommends that coffee is served hot. Ideally between 82°C and 85°C. Such hot coffee can be dangerous to scald the tongue and also due to the individual sensitivity of each coffee drinker.

The coffee rating should start at around 76°C. At this temperature, concentrate on the perception of aromas, as volatiles (aroma carriers) are quickly released with the steam rising from a cup of hot coffee.

Remembering aromas is easy, naming them needs practice.

The so-called smell memory is almost perfect. But finding a specific name is much more difficult. Equip yourself with a set of 6 or 36 coffee aromas and train your scent-defining skills.

Between 70°C and 50°C, the bitter flavours of coffee are most pronounced. The intense roast-like flavor is quite uniform evenbetween different coffee samples. The most intense bitterness can be felt around 56°C.

Dropping below 50°C with lower evaporation also decreases the chance of clearly detecting coffee aromas. Bitterness recedes and more complex flavour combinations are introduced. Firstly, acidity, but above all sweetness comes into play. Around 44°C, the sweetness of the coffee is most apparent.

As the coffee cools further, the changes become less pronounced. You can detect fruity, floral and herbal notes and the flavours of the coffee become well defined. Cold coffee is then associated with acidity, which is most evident in a cup of coffee at around 25°C.

Volatile and non-volatile substances in coffee

During the roasting process, chemical changes occur in each coffee bean. Some compounds are formed others are degraded. These changes in the coffee through roasting lead to the formation of volatile substances - aromas - which are an important criterion for coffee evaluation in cupping.

Non-volatile compounds are also altered by roasting. For example, chlorogenic acid is formed by trans-cinnamic and quinic acid, creating bitter coffeeflavours. Carbohydrates and polysaccharides in coffee also contribute to the aroma. In particular, they contribute to the perceived sweetness and create the viscosity of the beverage.

The higher amount of amino acids in green coffee then means more reactions with reducing sugars. Aneffect known as the Maillard reaction in coffee roasting, which produces thetypical brown colour of roasted coffee.