Subject: Role of CO_{2 in the organoleptic appreciation of champagnes - Experimentation and methodological contributions}

Summary : Although easily detectable visually, the olfactory and taste impacts of CO₂ in champagnes were still largely unknown. To identify them, the bibliography and the many variability factors prompted us to start working with water, a simpler medium than champagne, to compare the intensities of perception of two states in pairs, with CO₂ and without CO₂, before moving on to champagnes and the qualification of perceptions. To this end, we used free descriptions because the sensory analysis techniques available did not allow us to obtain reliable olfactory descriptions due to the very rapid evolution of the wines by the effect of degassing, and by very significant differences in inter-individual perceptions.

We identify three main effects with their physiological origins:
- CO inhibition₂ on aromatic molecules,
- increased acid perception
- and the masking of the bitter perception.

Also, the CO₂ forming an integral part of a champagne, the latter with CO₂, is defined as 'pleasant' and 'fresh' on the nose, with a 'firm_attack', and a 'long_finish'. The absence of CO₂ generates a negative hedonic perception with terms like 'evolution' in the nose, 'lack_of acidity', 'fatty_mouth', 'flat_mouth', 'alcoholic', 'watery' and an 'alcoholic_final'.

These results also showed all the variability of the sensory text collected, its specificity, and the insufficiencies of sensory metrology in the face of olfactory complex and evolving products; we then propose a new general descriptive model, the Pivot© Profile, based on pairwise comparisons.

Its principle: This method is based on a free expression of the difference between two products, one of which is considered as a pivot, and which will always be present for all the comparisons; then these qualifiers perceived as more and less are counted (additions for the 'pluses', and subtractions for the 'minuses') per product evaluated, after having been grouped if necessary by grids of synonyms. The processing of these counts then makes it possible to identify the characteristics of each of the products by considering the terms of all the judges; it is also possible to identify the characteristics of each of the judges by considering the terms of all the products for each of the judges.

Following the presentation of the method, different applications are given below.

Presentation of the Profil Pivot© method

(Context and presentation)

Creation of a link between sensory description and evocation with the help of Pivot Profile©

A. Callac, C. Postic, E. Guidat, M. Kotulak  Bertrand Thuillier, A.M. Pensé-Lhéritier

Various research works were carried out after our first publication on the Profil Pivot© method, in collaboration with professors Catherine Dacremont, Dominique Valentin and Richard Marchal.