Comparison of descriptive analysis, projective mapping and sorting performed on pictures of fruit and vegetable mixes

In this study the ability of three sensory methods to describe differences among visual stimuli was evaluated. We compared the two fast alternative sensory methods, projective mapping (PM) and sorting, to a generic descriptive analysis (DA), using visually different pictures of fruit and vegetable mixes. Thirty-two pictures of different fruit and vegetable mixes were evaluated by two different panels (11 assessors each) using the three sensory methods. The results were compared to each other to find which of the two alternative descriptive methods, PM and sorting, lead to most similar results compared to DA. Further, the effect of replicate evaluations in fast alternative methods was assessed for visual stimuli, where the 11 assessors, conducting both the PM and sorting tasks, evaluated all pictures in duplicates. Last, an alternative analysis method to multidimensional scaling (MDS) for sorting data was evaluated, to elucidate if more detailed results could be obtained with the alternative DISTATIS procedure. Compared to DA, results obtained from both sorting and PM were similar, and similar main conclusions could be drawn from all three sensory methods. However, both PM and sorting were able to separate the samples to a higher degree than DA. With regards to the two data analysis techniques for sorting data, samples were found to group more tightly when analyzed by DISTATIS compared to MDS. Even for visually different samples, product maps changed over the replicates in the PM and sorting tasks, indicating that assessors changed their evaluation criteria when performing a holistic product evaluation.