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Sensory Research

Sensory research is a scientific approach for evoking, measuring, analysing and interpreting responses to goods via the five senses: 

sight, smell, touch, taste, and sound.

What is Sensory Research?

How tasty a product is, how different two products are and how taste changes over time are only a few of the questions which can be answered through sensory research. 

 

Sensory research can address these types of questions which are relevant and of great importance in food and non-food businesses alike. This kind of research is a well-established area in an industry where sensory science is frequently used to assess product quality

-as well as in academia- where fundamental science on how humans taste food is under investigation.

Why is it important?

Precision, accuracy, and sensitivity are all important aspects in sensory evaluation, as is minimizing false-positive outcomes. The sensory scientist should complete these four tasks: problem characterization, test design, instrumentation, and result interpretation, as the foundation of a reliable sensory evaluation. To conduct a successful sensory evaluation, the researcher must first understand the aim of the study, subsequently choose a suitable experimental design, recruit panelists appropriate for the task, prepare and display samples properly and accurately interpret the data. 

 

These tasks were traditionally completed with a pen and paper. Despite the fact that paper forms are relatively inexpensive, designing paper responses for various types of designs can be time-consuming and error-prone when transferring data from the paper to software for data analysis. Using a computerised system has numerous advantages for data collection, including the ability to design, analyse and report data quickly and without the risk of human errors.

Sight

Color, size, shape, texture, consistency, and opacity are all factors that the eyes take into account while judging the initial quality of food. For instance, through the sense of sight, we can determine ripeness of a fruit or the degree to which the meal has been heated. This first evaluation can determine the desirability and acceptance of a food.

Smell

Our sense of smell, or olfactory sense, also plays a role in determining the quality of food. Temperature affects the volatility of scents. Because odor is carried by only volatile molecules in the form of gas, it is simpler to detect hot foods than cold foods. Hot tea, for example, is considerably easier to detect than iced tea, and baked goods have a stronger odor than ice cream. Hunger, satiety, mood, focus, the presence or absence of respiratory illnesses, and gender all affect human subjects’ sensitivity to odors.

Taste

Taste is the most influential aspect in their food selection. Taste buds are located largely on the surface of the tongue, in the mucosa of the palate, and in parts of the neck. Each taste bud has a pore in the center where saliva gathers. When food enters the mouth, it dissolves in the saliva pools and comes into contact with the gustatory cells’ cilia, which are small hair like projections.

 

Gustatory cells communicate with the brain via cranial nerves. The nerve electrical impulses are then translated by the brain into sensations that individuals perceive as “taste.” Flavor is a broader term than taste, which is based on the feeling produced by stimulating the taste buds. Flavor is the sensation of taste, fragrance, and mouthfeel combined. Textural and chemical sensations like as astringency, spice heat, coolness, and metallic flavor are all part of mouthfeel.

Touch

The sense of touch conveys texture perceptions to us through mouth sensations or the skin. If the first input with products is visual; the second is touch, which can be felt directly through the fingers or indirectly through eating utensils; and the third is the sensation in the mouth (mouthfeel), which is sensed by the teeth and tactile nerve cells on the tongue and palate. Texture perception comprises tactile feel properties, (i.e., grainy, gritty, crystalline, flaky) or moisture properties (i.e., wetness, oiliness, moistness, dryness).

Sound

Another sense that is used to assess food quality is sound. Sizzling, crunching, cracking, bubbling, squeaking, dripping, exploding, and crackling are just a few of the sounds that may convey a lot about a food.

Variables Controlled During Sensory evaluation

Sensory testing is of two kinds: analytical and affective testing. 

  • The analytical testing includes discrimination methods to determine the difference between products and descriptive methods to indicate which sensory attributes are present in the product and to measure it’s intensities. 
  • The affective testing also known as hedonic testing is about the consumer liking and preference (Society of Sensory Science, 2016).

 

Panelists taking part in the discriminating and descriptive tests are called trained panelists. They are carefully selected and trained to evaluate sensory characteristics of a food. A trained panel may consists of 5 to 10 panelists. The consumer panel is recruited to participate in the sensory test to indicate product liking and preference. It might consists of 100 or more panelists (Rogers, 2018)

Recruitment of trained panel

  • Internal recruitment: Panelists are recruited within the organization working in different departments like packaging, marketing or finance. It is recommended not to include personnel from the commercial or technical department as they are closely involved with the product and their ratings might be biased.
  • External recruitment: Panelists are recruited from outside the organization through advertisements in local newspapers or press. (ISO,1993)
Selection criterion
Selection criterion for trained panelists:
  1. Interest and motivation
    Candidates who are interested in the product that is being investigated and in the sensory analysis.

  2. Attitudes to foods
    If a candidate has a strong dislike for certain food and drinks should not be screened.

  3. Knowledge and aptitude
    The candidates should have capacity to concentrate and not affected by external influences.

  4. Health
    The candidates should be in good health. They should not suffer from any food allergies or take any medications that affects their senses.

  5. Ability to communicate
    Candidates should be able to describe the sensations they perceive while eating or drinking. This trait is very important for screening the descriptive panel.

  6. Availability
    Candidates should be available for training and frequent assessments. If someone travels frequently or have hectic work schedule then they should not be screened.

Screening

It is recommended that candidates go over the following screening steps:

  1. Color vision
    If someone has abnormal color vision or color blindness then they cannot be included in the panel as they won’t be able to perform the task of judging colors. The assessment of the color vision can be performed by optician or using ishihara test.
  2. Matching test
    In this test, samples of different odors (For example: vanilla, thyme, floral) above the threshold are prepared and candidates are asked to familiarize themselves with those odors. Then they are presented with series of samples labelled with the three digit code and they have to match the samples and describe the sensation they are experiencing.
  3. Detection of basic taste
    Candidates are given solutions of sweet, bitter, salty and sour taste along with water. They have to correctly identify all basic tastes.
  4. Odor recognition test
    In this test candidates are given different odor samples related to the product that will be eventually evaluated. Some odors are easy to recognize for example: tea, coffee, garlic, orange while others might be unfamiliar (like: rancid butter, mushroom, bitter almond, camphor). In order to become part of the panel candidates must be able to identify 65% of the odors.
  5. Texture characterization
    In this test candidates are provided samples of different textures such as soft, crunchy, gummy, spongy and candidates have to describe the texture of each product. If they are able to score 65% of the maximum score then they are included in the panel.

General guidance for design of test rooms

The testing rooms used in the sensory evaluation should have minimum distractions and it should have controlled conditions such as temperature, humidity, air circulation, color and lighting.

 

The test facility should at least consist of testing booths and preparation area. But if possible then there should be waiting area for panelists, coatroom, storage room for supplies and samples. The testing facility shouldn’t be close to busy area for example: near a cafeteria. It is also important to make sure the facility can be easily accessed by panelists with physical disabilities.

Temperature and humidity

The temperature and humidity of the testing booth should be 22–24°C and 45–55% respectively (Morten Meilgaard, Gail Vance Civille and B Thomas Carr, 2007). There should be no odor in the booth that influence the sensory evaluation of a panelist. This can be achieved by installing activated carbon filters in the ventilation system (ISO,2007)

Color and lighting

The walls of the booth should be off-white and lighting should be uniform and controllable. The ideal illumination for the testing booth is 700-800 lx (Lawless & Heymann, 2010). Colored lights can be used to mask the differences in product appearance.

References

Society of Sensory Science. (2016). Society of Sensory Science. [online] Available at: Society of Sensory Professionals .

Rogers, L., 2018. Sensory Panel Management: A Practical Handbook for Recruitment, Training and Performance. Woodhead Publishing.

International Organization for Standardization [ISO](1993) – Sensory analysis – General guidance for the selection, training and monitoring of assessors

Morten Meilgaard, Gail Vance Civille and B Thomas Carr (2007). Sensory evaluation techniques. Boca Raton: Taylor & Francis.

‌International Organization for Standardization [ISO](2007) – Sensory analysis – General guidance for the design of test rooms.

LAWLESS, H. T., & HEYMANN, H. (2010). Sensory evaluation of food: principles and practices. New York, Springer.