Sensory analysis (or sensory evaluation) is a scientific discipline that applies principles of experimental design and statistical analysis to the use of human senses (sight, smell, taste, touch and hearing) for the purposes of evaluating consumer products. The discipline requires panels of human assessors, on whom the products are tested, and recording the responses made by them. By applying statistical techniques to the results it is possible to make inferences and insights about the products under test. Most large consumer goods companies have departments dedicated to sensory analysis. Sensory analysis can mainly be broken down into three sub-sections:
- Effective testing (dealing with objective facts about products)
- Affective testing (dealing with subjective facts such as preferences)
- Perception (the biochemical and psychological aspects of sensation)
This type of testing is concerned with obtaining objective facts about products. This could range from basic discrimination testing (e.g. Do two or more products differ from each other?) to descriptive profiling (e.g. What are the characteristics of two or more products?). The type of panel required for this type of testing would normally be a trained panel.
There are several types of sensory tests. The most classic is the sensory profile. In this test, each taster describes each product by means of a questionnaire. The questionnaire includes a list of descriptors (e.g., bitterness, acidity, etc.). The taster rates each descriptor for each product depending on the intensity of the descriptor he perceives in the product (e.g., 0 = very weak to 10 = very strong). In the method of Free choice profiling, each taster builds his own questionnaire.
Another family of methods is known as holistic as they are focused on the overall appearance of the product. This is the case of the categorization and the napping.
Also known as consumer testing, this type of testing is concerned with obtaining subjective data, or how well products are likely to be accepted. Usually large (50 or more) panels of untrained personnel are recruited for this type of testing, although smaller focus groups can be utilised to gain insights into products. The range of testing can vary from simple comparative testing (e.g. Which do you prefer, A or B?) to structured questioning regarding the magnitude of acceptance of individual characteristics (e.g. Please rate the "fruity aroma": dislike|neither|like).
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Perception involves the biochemical and psychological theories relating to human (and animal) sensations. By understanding the mechanisms involved it may be possible to explain why certain characteristics are preferred over others. When sensory analysts study the relationship between a given physical stimulus and the subject's response, the outcome is often regarded as a one-step process. In fact, there are at least three steps in the process. The stimulus hits the sense organ and is converted to a nerve signal that travels to the brain.The brain then interprets, organizes and integrates the incoming sensations into perceptions. Finally, a response is formulated based on the subject's perceptions <Schiffman 1996>. In dealing with the fact that humans often yield varied responses to the same stimulus, sensory professionals need to understand that differences between two people's verdicts can be caused either by a difference in the sensation they receive because their sense organs differ in sensitivity or by a difference in their mental treatment of the sensation,e.g., because of a lack of knowledge of the particular odor, taste, etc or because of lack in training in expressing what they sense in words and numbers. True training and the use of references, sensory professionals can attempt to shape the mental process so that subjects move toward showing the same response to a given stimulus.<Sensory Evaluation Techniques, Fourth Edition>
Notes and references
- ASTM MNL14 The Role of Sensory Analysis in Quality Control, 1992
- ISO 16820 Sensory Analysis - Methodology - Sequential Analysis
- ISO 5495 Sensory Analysis - Methodology - Paired Comparisons
- ISO 13302 Sensory Analysis - Methods for assessing modifications to the flavour of foodstuffs due to packaging
- Sensory Evaluation Techniques- Morten C. Meilgaard, Gail Vance Civille, B. Thomas Carr - 4th edition, 2007