Optimized Descriptive Profile: How many judges are necessary?

• Ideal number of judges for ODP technique was obtained by computer simulation.
• RMSEL, interaction effect, significance of treatments and RV were evaluated.
• Different food matrices and attributes need diverse number of evaluations.
• Sixteen judges allowed compliance for all criteria.
• RMSEL presented more rigorous criteria.

The cost associated with descriptive sensory tests can be derived primarily from two sources: (i) execution time of the test and (ii) the number of judges participating. The Optimized Descriptive Profile (ODP) technique is a new methodology that proposes to reduce test time through an optimized sensory evaluation protocol. The objective of this study was to determine the optimal number of judges for descriptive sensory evaluation using the ODP, so as to show that the technique presents a reduction in time, money and efforts for conducting the methodology, and also in relation to the number of participants making up the panel. The study to determine the optimal number of judges was conducted using the data re-sampling technique for a panel original composed of 26 judges, by means of computer simulation. Data from the complete panel considering 10,000 sub-groups was re-sampled with replacement. The criteria for determining the ideal number of judges were: (i) acquisition of an experimental error less than or equal to the error verified in the reference methodology (Conventional Profile), (ii) obtaining interaction between sample and judges, in terms of size and stability, similar to interaction obtained by complete panel, (iii) concordance rate among products, using paired comparison (sample discrimination), similar to the full panel and (iv) minimal loss of information in the sensory map. The criterion for magnitude of the experimental error estimate showed to be the most robust measure for determination of the number of judges necessary for the ODP technique. Because this technique requires low levels of training of the judges, evaluation of these criteria is extremely important since a larger residual random variation can usually be observed. The criteria for magnitude of the experimental error, interaction between samples and judges effect and concordance rate in paired comparisons were met when sixteen evaluators was used.