Wine sensory benchmarking (Part 2): The pros and cons of three suitable sensory methods

by | Mar 1, 2020 | Oenology research, Winetech Technical

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Benchmarking is a tool used in the wine industry for branding, re-branding and product development.

Rapid sensory methods suitable for benchmarking

Comparing the appearance, aroma (“nose”), taste and mouthfeel (“palate”) of a wine to other wines on the market, can form a key part of the overall benchmarking process.

Check-All-That-Apply (CATA), Pivot© Profile (PP) and Polarised Sensory Positioning (PSP) are sensory methods that can be used to assess differences and similarities between wines. This implies that all three of these methods can be useful during the benchmarking process when comparing wines to each other. Choosing a fit-for-purpose method for a specific benchmarking exercise requires taking into account the strengths and weaknesses, and pros and cons of each method. In order to determine and discuss the pros and cons of these methods as benchmarking tools, it is:

  • Important to know how these methods work and
  • to test them against each other by analysing the same set of wines using the same panel with all three methods independently.

How do the sensory methods work?

CATA is a multiple choice-based method that originated from marketing research, where it is used in surveys. Adams and co-workers used it for the first time in 2007 to profile food products in terms of their sensory characteristics. This method is widely used for profiling food products one-by-one using a tick list also called the CATA question. These CATA lists can consist of words or phrases. When a wine is profiled, the list consist of sensory descriptors, for example “guava”, “green pepper”, “oaky”, “buttery”, etcetera.

The most challenging aspect of CATA is to decide how to construct the list and which terms to use. Vocabulary developed to describe specific wine styles and cultivars is available within the wine industry and wine appreciation community in the form of aroma wheels and booklets. This “wine language” was developed by various role players, such as academic institutions, wine tasting groups, wine writers and critics, over the years. It can be used as terms on CATA lists and thus in formal sensory evaluation to describe a wine’s properties.

Pivot Profile (PP) is a relatively new sensory method that was proposed in 2015 by the Frenchman, Bertaut Thuillier, and his colleagues in Dijon and Cedex. The method was specifically tested on Champagne and was proposed as an easier alternative for free description of wine by wine industry professionals. When performing PP, wine judges compare each wine (to be profiled) to the reference wine called the “pivot” sample. They have to write down all the attributes, that they perceive as “less intense” and “more intense”, in the wine sample (to be profiled) than the pivot sample. PP provides information on the intensity of the attributes relative to the pivot sample and is for that reason particularly suitable when wines are compared. The most difficult aspect with PP is the choice of the pivot sample when this method is used for profiling purposes. When direct comparisons between wines are required, the choice of the pivot sample is set and not a problem.

Eric Teillet and his colleagues first introduced polarised sensory positioning (PSP) to compare the sensory characteristics of different bottled waters. The idea behind the PSP was to describe products relative to reference products as a whole rather than in terms of sensory attributes. Judges are asked to indicate on a line scale, ranging from “exactly the same” to “completely different”, how similar the wine sample is to the “pole” or reference sample. This method can be particularly useful when it is difficult to describe the specific sensory attributes of every product, for example when bottled waters are assessed. Since wine is a complex product, it is often hard to describe. PSP could be a useful method if a comparison between different wines is the main aim. The main drawback of PSP is that specific attributes describing the sensory properties of the wines analysed are not obtained, only a degree of similarity to the “poles”. In some cases where a relatively fast comparison or benchmarking is required, the specific sensory characteristics might not be required.

How do the methods compare?

Understanding how each method works, can help panel leaders to choose a method for a specific benchmarking exercise, but it is important to test:

  • The effectivity of each method to describe differences between samples,
  • how well the panel using the method perform and
  • how difficult the panel experience the method.

The panel performance is measured in terms of the repeatability of the individual judges and the consensus or agreement among all the judges. In other words, will the judge describe the sample the same if he/she has to do it twice (repeatability) and do the judges use similar terms to describe the same wine, are they in agreement (consensus)?

In a study conducted at Stellenbosch University, in collaboration with SenseLab, CATA, PP and PSP was used for benchmarking and the results from the three methods were compared. The study was conducted on two sets of wines, five premium Sauvignon blanc wines and five premium Chenin blanc wines. A panel of 15 trained sensory judges tasted the wines. After every sensory evaluation session, the judges were asked to rate the ease of the method on a 9-point scale ranging from “extremely easy” = 1 to “extremely difficult” = 9.

The three methods had similar abilities to differentiate between the wines and indicated well which wines were similar and which wines were different. The judges were repeatable and the consensus was good for all three methods, but CATA was experienced as significantly easier than PSP and PP. PSP was the fastest to perform, but it is important to note that PSP does not provide specific attributes.

To summarise, CATA was the easiest for the judges to perform. It provides a detailed description of the sensory profiles of all the wines, but the samples are not compared directly and similarities and differences could easily be lost using this method. PSP is a good option if a fast comparison is needed and it is important to know how similar or to which wines the analysed sample is closest, but detailed profiles are not needed. If a comparison and detailed profiles relative to a wine is required, then PP will be a good option. Another option would be to perform PSP in combination with CATA, where CATA can be used to obtain a detailed profile and PSP to determine how similar or different the wines are.

Abstract

Three rapid sensory methods were identified as suitable tools to use during benchmarking, namely:

  • Pivot Profile (PP),
  • Polarised Sensory Positioning (PSP) and
  • Check-All-That-Apply (CATA).

When CATA is conducted, sensory judges select the attributes that describe a wine from a predetermined list, for example an aroma wheel. Performing PP, each wine in the set is compared to a reference wine, the pivot. Sensory judges are asked to provide for each wine the attributes perceived “less intense” and “more intense” than the pivot sample. PSP entails the rating of each wine against a reference wine on a line scale ranging from “exactly the same” to “completely different”. The pros and cons of these methods were investigated and compared to each other. Judges’ repeatability, consensus and difficulty of the method were assessed. Although the judges experienced CATA as the easiest method to perform, direct comparison of wines during tasting are only achieved with PSP and PP. It is also important to note that PSP does not provide sensory descriptors or a profile, but only an indication of how similar or different each wine is from the reference wine.

Acknowledgements

This research was funded by Winetech, Project IWBT W13/02: “Rapid descriptive sensory methods for wine evaluation – special focus on further optimisation of rapid methods and streamlining of workflow”. NRF and THRIP are acknowledged for financial support.

References

Adams, J., Williams, S., Lancaster, B. & Foley, M., 2007. Advantages and uses of Check-All-That-Apply response compared to traditional scaling of attributes for salty snacks. In: 7th Pangborn Sensory Science Symposium. 16 August 2007, Minneapolis, USA. pp. 12 – 418.

Campo, E., Do, B.V., Ferreira, V. & Valentin, D., 2008. Aroma properties of young Spanish monovarietal white wines: A study using sorting task, list of terms and frequency of citation. Australian Journal of Grape and Wine Research 14, 104 – 115.

Teillet, E., Schlich, P., Urbano, C., Cordelle, S. & Guichard, E., 2010. Sensory methodologies and the taste of water. Food Quality and Preference 21, 967 – 976.

Thuillier, B., Valentin, D., Marchal, R. & Dacremont, C., 2015. Pivot© profile: A new descriptive method based on free description. Food Quality and Preference 42, 66 – 77.

– For more information, contact Jeanne Brand at jeanne@sun.ac.za, Leanie Louw at leanie@senselab.co.za or Hélène Nieuwoudt at hhn@sun.ac.za.

 

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