Ipsos Encyclopedia - Sensory Evaluation

Definition: In the market research world, the expression sensory testing is frequently misused to describe a product test where consumers are evaluating a product against sensory attributes. In other words a normal taste test, also called a product test. However in the scientific world, a sensory test is different from a consumer acceptance test. A better expression to use is Sensory Evaluation.

Ipsos Encyclopedia - Sensory Evaluation

Sensory Evaluation is defined as follows:

"Sensory Evaluation is a scientific discipline used to evoke, measure, analyse and interpret reactions to those characteristics of foods and materials as they are perceived by the senses of sight, smell, taste, touch and hearing" (Sensory Evaluation Division of the IFT, Anonymous, 1975).

This is what is needed for a researcher to conduct sensory evaluation:

  • A group of 10-12 people that have been qualified to be users and likers of the category:
    • selected to be excellent discriminators
    • able to detect fine sensory differences
    • grouped to be describing a product using all their senses
    • familiar with a system to score their perceived sensory intensities
  • A group of scientists capable to run such a sensory panel.
  • The facilities for doing individual taste testing in booths.
  • The statistical software needed to run the data evaluation and measure panellists' performance.

Most of the time, Ipsos' larger clients are running sensory evaluations at their facilities. However, Ipsos has its own facilities for sensory evaluation (in Sweden) and is ready to partner with sensory agencies globally.

Once gathered, the sensory profile for each tested product may be merged with consumer (i.e. untrained respondents) evaluations of liking or acceptability and used as a basis for modelling (e.g. product optimisation).

The most common methods for descriptive sensory evaluation are Quantitative Descriptive Analysis (QDA) and Sensory Spectrum.

Ipsos Point Of View

The separation of the psychological tasks "liking" and "description" allows the relevant consumer groups to focus on what they can do best:

  • Target group consumers focus on expressing the degree of liking of various products. These consumers are unbiased, they have no prior technical knowledge about products, and they are representative of the target group. They don't discuss sensory descriptors with each other, therefore the language used in the consumer test is easy and straightforward. 
  • Sensory panellists are typically users and likers of the product category. However mostly they are not target group consumers as they test products in one central location, which is often in a different country from the target market.

Panellists are selected to be the best discriminating taste testers who develop their own language to describe the products. The sensory vocabulary is therefore much richer and longer than the attributes that consumers can go through in a Central Location Test. On the other hand, sensory panellists focus on describing intensities, they don't assess how much they like the different products. Similar to consumers, they have little knowledge about the business background or the tested products.

A sensory panel typically consists of 10-12 panellists, who evaluate products in triplicate, every product being tested three times, to ensure statistical certainty. The sensory attributes cover all sensory modalities, i.e. all perceivable sensations (Appearance, Aroma, Texture, Mouthfeel, Sound, Flavour and Aftertaste). Typically we find 40-50 different sensory attributes in products.

The most popular method for sensory evaluation is called QDA Quantitative Descriptive Analysis). Here, panellists are presented with a range of products within a category, and they generate all words themselves, by majority voting. All panellists then use the same list of words for all products. Panellists score intensities on a line scale, and have the freedom to score according to what they perceive individually. Usually the panel leader does not suggest terms, but might in certain cases (e.g. the word rancidity at the beginning of a shelf life test).

The second most used method is Sensory Spectrum. Here, for some variations of the method, the panel leader comes with terms to the panellists. Often their language is more technical, it could use chemical terms for instance. The key difference versus QDA is calibration. Panellists are expected to all score the same, by being presented with many references (they get a 5 % sugar solution, and are expected to score this product a 5 on a 15 point sweetness scale).

There are many other methods. One of these is Free Choice Profiling. Every panellist generates their own vocabulary, that could be different from the rest of the group. Here you need special analysis like Procrustes analysis. The benefit is that every perception that any panellist has is included. With the other methods, if one or two people pick up something that the others don't perceive, the term doesn't usually become part of the score card.

Our Experts

Best reading

Society of Sensory Professionals (SSP), based in the US, gives one page overviews, including QDA and Spectrum.

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