Study of the influence of line scale length (9 and 15 cm) on the sensory evaluations of two descriptive methods

The line scale is widely used in different lengths to quantify the intensity of descriptors in sensory evaluation. Since studies related to its size are still limited the objective was to determine what variables of descriptive sensory evaluation can be influenced when different scale length is considered in two different methods: Optimized Descriptive Profile (ODP) (low degree of training) and Conventional Profile (CP) (high degree of training). Five chocolate samples were evaluated by two panels, one using the 9 cm and the other using the 15 cm line scale. The panels performed the sensory analysis using the ODP and after the CP method. The following criteria were investigated: interaction between sample and evaluator, discriminative capacity, repeatability of results, and frequency of score use on the unstructured scale. The influence of scale length on sensory responses was similar in the two methods (ODP and CP). When comparing the two scales in both methods, it was observed that the 15 cm scale resulted in an improvement in discriminative capacity, reduction of interaction and the evaluators tended to distribute their ratings more evenly across this scale length. The repeatability of results showed a slight tendency to be better on the 9 cm scale.