Selection, training and calibration of sensory panelists

MEASUREMENT tools are most important in understanding product characteristics necessary in quality development. Particularly for the food industry, human perceptions that lead towards final judgement about a product under study, provide one of the best measures absolutely necessary in product development and quality monitoring efforts. To achieve accurate and reliable sensory evaluation results, proper selection, training and calibration of sensory panelists (SP) are very important activities which need to be properly executed. The well-trained and maintained SPs serve as the instruments which cannot be replaced by any objective or physical measuring tools utilised especially in food research and quality assurance. Furthermore, these “human instruments” have to be properly maintained and regularly calibrated to ensure that their performance remain accurate and reliable through time. Retention of properly selected, trained and calibrated SPs is thus, an imperative in the food enterprise.

Sensory evaluation concept and applications

The Institute of Food Technologists’ Sensory Evaluation Division defines sensory evaluation (S.E.) as “a scientific discipline used to evoke, measure, analyse and interpret sensations as they are perceived by the senses of sight, smell, taste, touch and hearing” (Prell,1976). As such, progress of the food industry underscores the importance of S.E. as follows: (a) S.E. plays a big role among the four major players in food manufacturing, namely Sales and Marketing (S&M), Research and Development (R&D), Quality Control (Q.C.) and Production; (b) use in development of food product profile through quantitative descriptive analysis (QDA); (c) necessary for measurement of customer acceptability which enables direct comparisons between competitors; and (d) S.E. serves as an important instrument in innovation activities.

Fig. 1. Role of sensory evaluation in the quality development cycle

Figure 1 shows S.E. (centre) as it is linked with the different stages of product quality development (Gatchalian and Brannan, 2011) which generally starts with: (a) “consumer preferences” at top of inner circle; connecting with (b) “product profile”; then with (c) “test procedures”; (d) quality control tests; (e) “system of recording and reporting” and (f) “trouble shooting”. The innermost arrows moves in reverse directions, since consumer complaint, implying “ trouble” requires review of all recorded observations and the other activities in the development cycle. Almost at every stage, measurements are related to product sensory attributes as they are perceived by the trained SPs (Gatchalian, 2018).

The outermost circle displays the four major players in the company engaged continually in product innovation, development and monitoring which require them to be in constant communication with each other, hence the two-way arrows. S & M. (I) are generally the ones in direct contact with the target or actual customers from whom they elicit information about product preferences; which are then reported to R & D (II) - who usually generates innovation activities starting with “product profiling”. When developing product design, inputs from Q.C. (III) are solicited to facilitate development of process and product specifications. Likewise, Production (IV) gets into the picture to check on feasibility. Hence, the external two-way arrows indicate constant communication between the four major players, from product concept to product market performance. In all these activities, S.E. plays a very important role especially since the final judge of a food product is the consumer. It is the SP who studies the product at various stages of development. They help identify the characteristics desired by the target consumers and finally ensures that these are maintained or improved during product life.

Fig. 2 Sensory evaluation set-up at Singapore Polytechnic Research Centre (Gatchalian, 2018)

Figure 2 shows the basic structure and process necessary for the conduct of a scientific S.E. A major requirement is a well-designed S.E. laboratory with evaluation booths linked to the sample preparation area. To ensure proper focus on the product being evaluated the conditions for doing the S.E. process must be controlled starting from sample preparation set-up to the conditions inside the booths where temperature and light intensity are controlled.  As such, the SPs themselves must have the least variation between each other and this can only be achieved through proper selection, training and calibration.

Selection of sensory panelists

SPs serve as measuring instruments approximating that of an objective equipment having the qualities of accuracy, precesion and reliability. Therefore, there must be enough opportunities to determine if the SPs meet these basic requirements. Most of these can be obtained through proper selection processes which usually start with knowing who are interested to become a panelist. This is done through a survey among the employees that asks basic information about the person’s background and physical health conditions. Also, certain attitudes like “Willingness” to be called upon on scheduled dates plus their Availability whenever called. Once these are established other qualities like Capability to do serious evaluation work, Sensitivity to sensory stimulus and Reliability to respond and provide consistent results or in short, the acronym WACS-R. There are specific tests which can be utilised to determine the existence of these characteristics.

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Author: MIFLORA M. GATCHALIAN, PhD is the  CEO of Quality Partners Company Ltd. She is an Academician Emeritus, International Academy for Quality (IAQ), and the founding president, Philippine Association of Food Technologists, Inc.