Discriminant tests: is there a difference between the samples?

Directional tests: do the samples differ for a given characteristic (attribute)?

Quantitative tests: how big is the difference between the samples?

Descriptive tests: what attributes characterize the sample?

Dynamic tests: how attributes evolve over time

Affective tests: what is the level of satisfaction of the sample?

Emotional tests: what emotions are evoked by the sample?

Discriminant tests will point out if there is a difference or similarity between samples. They are fairly simple to perform and do not require special skills from the panellists but they need to involve a relatively high number of panelists in order to obtain reliable results. Discriminant tests are quick and easy to implement, making them an ideal choice for sample screening or routine analysis. Most of the tests in this category allow to compare only two samples at a time. The better-known sensory test in this category is the Triangular test; in a Triangular test, three samples are served to each panelist. Two of them are identical and one is different. The panelists are asked to indicate the sample perceived as different.

Directional tests focus on a specific attribute (e.g. sweet, bitter, etc.). These sensory tests are also quite simple and quick to perform and require limited skills from the panelists. In addition to analytical attributes, hedonic attributes such as preference can be taken into consideration. Among the most used tests in this category, we find the Ranking test, during which the panelists are asked to sort the samples based on the intensity of the attribute analysed(e.g. from the saltiest to the less salty).

Quantitative tests, are able to detect possible differences between and allow the panelists to rate them on a scale. However, in order to use these sensory tests, the panelists must be instructed beforehand. The sensory tests belonging to this category allow to compare multiple samples simultaneously. Among the most common quantitative tests we include the Difference vs. Reference test, which is a particularly useful during quality control. The panelists are asked to rate on a scale the magnitude of the difference for each tested sample compared to a reference sample.

Descriptive tests are considered among the most important in the field of sensory science, as they allow the identification of the distinctive characteristics (attributes) of a product. The information that these sensory tests provide is very powerful although they are considered more complex to manage than the other tests. For this reason, in recent years, research has worked a lot to develop “quick” descriptive tests, capable of delivering results without using a trained panel. The CATA (Check All That Apply) test is one of the quick methods. It requires the panelist to pick from a list of predefined attributes, the characteristics that best describe the product under evaluation.

Dynamic tests are more complex as they allow to determine the evolution of attributes during the evaluation of the product. These sensory tests can only be conducted using an IT tool since the evolution of the attributes must be recorded as a function of the time spent during the evaluation of the sample. The best known of these tests is the Temporal Dominance Sensation (TDS); with this test the panellists select the dominant attributes (e.g. sweet, bitter, salty) as they evolve during the product consumption (i.e. for food products, during mastication).

With hedonic tests we leave the field of analytical tests and enter that of affective tests. The sensory tests in this category allow to know the preference score of a product. They have a subjective character and for this reason they must be conducted on a large number of panelists, possible picked among a group of consumers product. The most common is the Acceptability test, in which the panelists have to indicate the level of satisfaction related to the sample on a scale. In these sensory tests, the panelists can be either asked to express a generalised evaluation or to rate one or more specific attributes (e.g. appearance, smell, taste etc … ) of the sample.

Emotional tests also take into consideration the subjective opinion of the consumer. These sensory tests allow to understand the emotions that are elicited during consumption of the products. The collection of emotional responses is done using a questionnaire. Although no specific training is requested for the panellists, some specialised skills are needed by the panel leader to draft an effective questionnaire and to interpret the results. The EmoSemio test is among the latest tests developed for this category. It asks the panellists to choose from a predefined list the (emotional) terms aroused by the product in question.