WINETECH Technical Yearbook 2020

SUMMARY Three rapid sensory methods were iden­ tified as suitable tools to use during bench­ marking, 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.

Method

Pros

Cons

Easier for judges to perform. Fewer data analysis steps.

Samples tasted one-by-one, not compared during tasting.

CATA

No attributes generated. No profile/word clouds generated. Difficult for judges to perform. Data analysis takes longer.

Provides general comparison between wines.

PSP

Wine compared to reference while tasting. Provides direct comparisons between wine profiles.

PP

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 rela- tively fast comparison or benchmarking is required, the specific sensory characteris - tics 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.

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.

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 Univer- sity, in collaboration with SenseLab, CATA, PP and PSP were 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 premiumChenin blanc wines. A panel of 15 trained sensory judges tasted the wines. After every sensory evaluation session, the judges were asked to rate the easiness of the method on a 9-point scale ranging from “extremely easy” = 1 to “ex- tremely difficult” = 9. The three methods had similar abilities to differentiate between the wines and indicated well which wines were similar

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