A chemometric study of pesto sauce appearance and of its relation to pigment concentration

Pesto sauce is a typical example of a food matrix in which aspect is of key importance to the final judgment of the consumer, and whose color strongly depends on the production process and on the ingredients. In view of this, the aim of the present work is to evaluate the possibility of quantifying the variability of visual aspect of different brands of pesto sauce, and its relation to the concentration of the main pigments. Sensory evaluation of the appearance of 12 commercial pesto samples was carried out by a panel of 16 assessors who evaluated quantitatively six visual attributes, suitably defined for the description of pesto aspect. A quantitative estimate of the performance of the panel was carried out by means of both univariate and multivariate–multiway chemometric tools (parallel factor analysis, PARAFAC). In addition, the relationship between the mean sensory scores values and the concentrations of chlorophylls, pheophytins and carotenoids was investigated by principal components analysis (PCA). Both PCA and PARAFAC showed good clustering of thesamples and a satisfactory degree of homogeneity of the assessors. Data analysis showed that assessors fundamentally agree about the main visual characteristics of pesto sauces, which are partly correlated with the concentration values of the main pigments.