Reproducibility evaluation of classification by expert assessors of raw ham red skin defect

The evaluation of qualitative characteristics of fresh pig thighs to be used for seasoning is generally made by expert assessors basing on visual aspect. To estimate quantitatively the degree of objectivity of human evaluation of visual aspect, digital images were acquired on a series of raw ham samples and then subjected to the classification by expert assessors in three quality categories related to the red skin defect. The results obtained from the panel have been analysed in terms of Validity (correctness of the response) and Reliability (ability of the assessor to reproduce his own results). Moreover, also the percentage of assignations of each sample to the correct class was estimated. The results suggest that the proposed approach can be used both to monitor the reliability of the single assessors, and to identify samples whose class assignation is reasonably indubitable.