le même processus pour tous - Université de Bourgogne

m.desmas@isa-lille.fr
Is it possible to learn beer sensory categories?
An exploratory study
Maud LELIÈVRE-DESMAS 1,2 , Sylvie CHOLLET 1 & Dominique VALENTIN 2
1 Institut Supérieur d’Agriculture, Laboratoire Qualité des Aliments, Lille, France
2 Centre des Sciences du Goût UMR 5170, CNRS, INRA, Université de Bourgogne, Dijon, France
Introduction
Context
Previous studies have shown that wine experts tend to develop common
mental representations of wines through frequent tasting and
consequently do not categorize wines similarly than novices (Solomon,
1997; Ballester et al., 2005, 2008).
Objectives
This study proposed to evaluate whether this phenomenon occurs for
beers, i.e. whether:
- novices could learn beer sensory categories through repeated
exposure to different beers,
- they could generalize their learning to identify category membership
of new beers.
↓
Two experiments with two different categorization criteria:
- fermentation type
- geographical origin
Figure 2. Percentages of correct answers (means ± standard error) for the
assessor group for top (TF) and bottom (BF) fermentation beers at T 0 and T final .
Conclusion
Products
> Fermentation type:
- 18 top fermentation beers (TF)
- 18 bottom fermentation beers (BF)
> Geographical origin:
- 9 German beers (G)
- 9 Belgian beers (Bg)
- 9 British beers (Br)
General procedure
Assessors
> 19 novices for each experiment
Method
> Training period to identify category
membership
> Comparison of correct beer
categorizations at T 0 and T final
> End of session T final : questionnaire
to identify possible learning strategies
Figure 1. Schema of general learning procedure
Results
Fermentation type Geographical origin
Learning data
> For learned beers: the percentage of correct answers is significantly higher
at Tfinal than at T0 .
> For unlearned beer: no difference between T0 and Tfinal. > 13 out of 20 beers had a higher percentage of correct answers at Tfinal than at T0 (including 5 beers with significant difference).
> No difference between top and bottom fermentation beers learning.
↓
Assessors learned to categorize almost all the beers individually but did not
generalize their learning to new beers.
Questionnaire
> Globally, consensus on the sensory characteristics of each category:
- TF beers: + alcoholised, + persistent, + sweet, + flavour, + heavy.
- BF beers: - alcoholised, - persistent, - flavour.
> Assessors did not used one or two characteristics to identify category
membership but more complex strategies (e.g., “This beer is dark, his
nose is intense, his taste is intense and alcoholised. I infer it is a top
fermentation beer”).
> Half of the assessors declared to have recognized a beer and to have
inferred its category (e.g. “ This beer looks like an Heineken or a 33
Export, I know that these beers are BF, so I infer this beer is BF”).
Learning data
> For learned beers: no difference between T0 and Tfinal but high variability
between beers in each category.
> For unlearned beer: no difference between T0 and Tfinal. > 6 out of 15 beers had a higher percentage of correct answers at Tfinal than at T0 (including 4 beers with significant difference).
> No difference between German, Belgian and British beers learning.
> Two British beers (stout beers) obtained higher results than the other
British beers, at T0 and Tfinal → more typical beers?
↓
Assessors learned to categorize only some beers individually and did not
generalize their learning to new beers.
Figure 3. Percentages of correct answers (means ± standard error) for the
assessor group for German (G), Belgian (Bg) and British (Br) beers at T 0 and T final .
Questionnaire
> Globally, less consensus on the sensory characteristics of each category.
> Assessors were in accordance on only some attributes, and they used a
lot of other attributes which did not lead them to the same conclusion.
↓
It can explain why there is no category learning of geographical origin
categories.
> Assessors seem to be able to identify category membership of learned beers (especially for fermentation categories) but not to generalize to unlearned beers.
> These results could be due to a short training period (9 sessions only), or to a high beer heterogeneity inside the categories to be learned, or to a nonadapted
learning context (do not correspond to daily life learning situations).