Wine tasting

Professional wine tasting requires mastery and profound knowledge of the taste properties of the molecules which make up this noble liquid. An interview with Axel Marchal, lecturer and researcher at the Institute of Vine and Wine Sciences, who features in the "top 20 people in wine" by La Vigne / Vitisphère monthly magazine.

  • 19/06/2017

Axel Marchal / ISVV / Universite de Bordeaux Axel Marchal / ISVV / Universite de Bordeaux

"Professional wine tasting goes beyond just a leisure activity. Rules and codes must be established to regulate the factors which have an effect on the person tasting (the 'taster')", explains Axel Marchal, university lecturer at the Institute of Vine and Wine Sciences (ISVV) at the University of Bordeaux. This scientific analysis is organized according to different stages.

"First of all, the taster studies the aroma by smelling the wine without swirling it in order to capture its most striking aromatic nuances. Then he/she swirls it to release the more delicate aromas. Once the wine hits the palate, various senses are stimulated all at once. A flow of air rising up to the nasal mucosa is what prompts odor perception: this means that it is not just flavor (salty, sweet, sharp, bitter) which helps the taster appreciate wine on the palate, but also the phenomenon of retro-olfaction".

Touch is also stimulated - the saliva proteins in the oral cavity are provoked (they form clusters) by the wine’s tannins. This results in a loss of lubrication in the oral cavity, which creates a "rough sensation on the tongue: astringency". Somesthesic sensations also play a part. "These include the feeling of hot or cold, such as those triggered by mint or pepper".

We are all different when it comes to wine tasting.

However, tasters soon move away from merely descriptive observations in favor of a form of representation. "Some tasters might talk about a sweet aroma when they smell a wine. But sugar is odorless! Their brain consciously or unconsciously associates the smell of the wine with sweet wines the person has previously tasted". Tasting therefore remains a subjective activity. "It’s like an abstract painting which every art lover interprets differently, moving beyond just style". Furthermore, there is no such thing as a perfect taster who can recognize every single aroma. "That would be pointless as tasting is less about description than identification".

An example? "If you ask Europeans to smell ethyl hexanoate, most will describe it as smelling like strawberries. However, Asian people describe it as having a similar smell to pineapple! This molecule can be found in both fruit, but people’s consumption habits affect their perceptions". To describe a large range of flavors, the vocabulary used is very subjective and each person’s preferences are reflected in their choice of words. This explains why for some people’s palates, sulfanylpentanone presents a boxwood aroma, whilst others describe it as cat urine! And this is why wine professionals sometimes prefer to use the scientific names of odor molecules to avoid any cultural confusion or personal judgement.

The two births of wine

Modern researchers are focusing on studying how taste is constructed by consumers. "Wine is born twice: once when the grapes are transformed into wine, and a second time in the taster’s mind", Axel Marchal explains. "Oenology is always highly interested in the composition of wine, its first birth. However, we are now launching a unique project uniting Bordeaux community’s two areas of excellence: neuroscience (with the NeuroMagendie Center), and oenology (with the ISVV). This collaboration between Professor Vincent Dousset’s team at the NeuroMagendie Center and the ISVV aims to gain a better understanding of what happens in a taster’s brain when they taste. The aim is therefore to shed some light on the mechanism of wine’s second birth!’