The nose has two pathways for perceiving aromas

When we talk about smell, we generally think of the act of bringing our nose close to food, a flower, or a cup of tea.

Aromatic molecules present in the air enter through the nostrils and reach the olfactory region located in the nasal cavities.

This perception is called orthonasal olfaction.

This is what you use when you open a tea bag and smell the dry leaves, or when you bring your nose close to the cup before drinking.

But there is a second pathway.

When the tea is in the mouth, some of its volatile aromatic compounds pass into the air present in the oral cavity. This air can then rise toward the nasal cavities through the back of the mouth.

The molecules then reach the olfactory system through an internal pathway.

This is retronasal olfaction.

Why do we feel like we are “tasting” aromas?

Because all the information arrives almost at the same time.

During a sip, the tongue detects the basic flavors. The mouth perceives the temperature. The oral tissues feel the texture and astringency. The nose receives the aromatic compounds.

The brain then brings all this information together into a single experience.

This is what we spontaneously call the taste of a tea.

Yet, when you describe a tea as floral, fruity, woody, honeyed, roasted, or citrusy, you are primarily using vocabulary related to smell.

The tongue obviously plays an essential role, but it never works alone.

What really happens during a sip

When tea enters the mouth, its temperature immediately begins to change. The liquid meets the tongue, palate, cheeks, and saliva.

Some aromatic compounds then leave the liquid phase and pass into the air in the mouth.

This air can rise toward the nasal cavity.

This is when certain notes suddenly become easier to recognize.

A tea that seemed simply vegetal to the nose can then evoke a white flower, ripe fruit, grain, spice, cocoa, wood, honey, or nut.

These words do not necessarily mean that the corresponding ingredients are present in the tea.

They are aromatic descriptors used to compare a perceived sensation with a familiar smell.

Why does exhaling through the nose change the tasting experience?

Try a very simple action.

Take a small sip of tea.

Hold it in your mouth for a few seconds.

Swallow.

Then exhale gently through your nose.

Sometimes an aroma becomes immediately more evident.

This exhalation promotes the passage of air toward the nasal cavity and helps make certain aromatic compounds perceptible through the retronasal pathway.

Retro-olfaction and mouthfeel: they are not the same thing

The two concepts are close and can easily be confused.

Retro-olfaction primarily describes a pathway for perceiving aromas.

Mouthfeel describes the duration during which sensations persist after the sip.

A long finish can therefore have a strong aromatic component related to retro-olfaction.

But mouthfeel can also include bitterness, sweetness, astringency, freshness, or tactile sensations.

Why does the same tea not smell exactly the same to the nose and in the mouth?

When you smell a cup directly, you primarily perceive an external aromatic environment.

When you drink, the olfactory signal combines simultaneously with flavors, temperature, saliva, tactile sensations, and the movement of the sip.

The brain therefore receives the same families of information in a very different context.

This is why smelling a tea never allows you to fully anticipate how it will behave in the mouth.

Some teas are spectacular to the nose but relatively simple in the mouth.

Others seem subtle when smelled but become much more complex once tasted.

Temperature also changes what we perceive

A scalding tea is rarely in its best condition for precise sensory observation.

Heat can dominate the experience and limit our ability to analyze nuances.

As the infusion cools, certain sensations become clearer.

A floral note may become sharper.

An impression of fruit, grain, or honey may emerge more easily.

It is therefore interesting to taste the same tea several times:

• when it is still very hot;
• a few minutes later;
• then when it becomes lukewarm.

This simple observation often reveals several facets of the same cup.

A very simple experience to try at home

Prepare an aromatically expressive tea.

Take a first sip while breathing normally.

Observe the sensations.

Then take a second sip and gently pinch your nose.

Swallow while keeping your nose pinched for a few seconds.

Then release it and breathe normally.

You can notice a very distinct change in aromatic perception.

This obviously does not mean that the nose “does it all.”

The tongue continues to perceive flavors, and the mouth perceives tactile sensations.

This experience simply shows the importance of smell in the overall construction of tasting.

Why do two tasters not always find the same aromas?

Perceiving a sensation is not enough.

You must then be able to recognize it.

Our brain continually compares new sensory information with our memory.

A person who has often smelled ripe apricots may spontaneously recognize an apricot impression.

Another may simply speak of yellow fruit.

A third may use the word peach.

Sensory vocabulary therefore depends in part on experience, dietary habits, culture, and individual memory.

This is why it is better to start with broad aromatic families rather than immediately looking for extremely precise descriptions.

Retro-olfaction can be trained

Learning to taste does not necessarily require an exceptional sense of smell.

A large part of progress comes from attention and memory.

When you cook or eat, take a few seconds sometimes to consciously smell:

• an orange peel;
• a lemon;
• an apple;
• honey;
• hazelnuts;
• cocoa;
• toast;
• spices;
• aromatic herbs.

Your brain gradually builds a library of smells.

When you encounter a similar sensation in a tea, it will become easier to recognize.

But vocabulary should never become a competition.

Saying “floral,” “vegetal,” or “slightly roasted” is perfectly valid if that is what you actually perceive.

Taste before reading the description

Here is a particularly useful exercise.

Do not immediately read the sheet for a tea.

Prepare it.

Smell it.

Taste it.

Note two or three impressions.

Only then compare your perception with the suggested descriptors.

This method allows you to distinguish what you actually perceived from what your brain might have been trying to recall after reading a description.

This is an important step in developing a more personal and precise tasting experience.

What retro-olfaction teaches us about tasting

A cup of tea does not have a single “taste” that we detect with a single sense.

Tasting results from a set of phenomena.

The leaf brings its composition.

The processing of the tea builds an important part of its profile.

The water extracts the compounds.

The temperature influences their expression.

The tongue detects certain gustatory dimensions.

The mouth feels the body, texture, and astringency.

The nose captures the aromatic molecules.

The brain finally brings all this information together.

It is only at this moment that the experience we call tasting is born.