What happens in our brains when we taste wine?

A golden color, the scent of hazelnut and ripe mirabelle plum, brioche aromas, umami and acidic flavors, a soft, enveloping texture and medium temperature. All this information from our senses reaches the brain at the same time. It receives it, selects it, prioritizes it and then synthesizes it to build a mental image of the wine. The brain works to reconstruct the taste.

To do this, it looks to memory. It probes the outside with what's stored inside. Emotions also come into play. There's no single place in the brain responsible for perceiving wine. It's constantly adapting to context and experience.

Visual information can overwhelm us

For the human species, the sense of sight is primordial. The brain relies above all on vision, even if this means inhibiting olfactory and gustatory centers, as demonstrated by a famous experiment carried out by Gil Morrot, Frédéric Brochet and Denis Dubourdieu in 2001. A white and a red wine were tasted by 54 oenology students. The red wine was in fact the same white wine with added colorant. To describe it, the students used olfactory descriptors usually reserved for red wine.

The experiment illustrates confirmation bias. The brain tends to confirm what it knows and anticipates. In a classic tasting (visual, olfactory then gustatory examination), we seek to validate by smell what we have seen, then to confirm in the mouth what we have smelled. Expecting to taste a red wine is already perceiving it as a red wine, so using an opaque container can give rise to a different vision of the wine.

We don't all smell the same

Olfaction is our most advanced sense. Our olfactory system uses over 400 receptors, compared with 3 receptors for vision.

A smell can take two routes. When smelling above the glass, odors are carried through the nose by the orthonasal route to the olfactory mucosa at the top of the nasal cavity. When the wine is in the mouth, it warms up and mixes with saliva, with subtle odor compounds (called aromas rather than "smells") mingling with the flavors.odors) mingle with flavors (salty, acidic, sweet, bitter, umami) and travel up the back of the mouth to the olfactory mucosa on exhalation.

To identify the taste, our brain compares it with the olfactory memory library. Other areas of the brain are activated. The brain processes the smell emotionally, links it to words or memories, probes our internal state (our appetite, for example)...

However, despite its great capacities, the sense of smell is the one with the greatest genetic variation. Two individuals have at least 30% of their receptors functionally different. For example, one-third to one-half of the population cannot smell the beta ionone molecule that makes up violet. This "olfactory color blindness" complicates the discussion of what we smell.

All the more so as experience plays a part in these variabilities. For the same fragrant cocktail, the linguistic frame of reference will differ from one person to another, depending on their experience or culture. If we can smell green bell pepper in certain wines, Chinese tasters who are unfamiliar with this vegetable will be more likely to speak of ginseng root, since the two have common chemical components.

Tasting is all about memory

In 2014, researchers at the Besançon University Hospital analyzed how wine-related taste sensations are processed in the brains of sommeliers and neophytes. MRI revealed a slower, more diffuse, more emotional reaction in the latter. In the sommeliers' brains, on the other hand, the responses were more analytical, condensed in a small area, drawing precisely on an ordered memory. These two systems of thought - analytical (what is it) and emotional (do I like it or not) - coexist in our brains. We can describe a wine without saying whether we like it, and we can like it without describing it. The expert can take either route.

Tasting therefore requires an essential organ: the brain. A rich memory and the ability to mobilize it are the strengths of wine analysis. The good news is that it's only a matter of practice.