Colorimetric and raman characterization as marketing value index of sicilian citrus

The aim of this work is the objective characterization, using non-invasive techniques, of Sicilian citrus fruits in order to identify univocal objective properties. Particularly, the goal of this work is to find an analytical relation between colorimetric and Raman results in order to create a predictive model based on the analysis of the present functional carotenoids groups. 8 different species, provided by “Paolo Lo Giudice” farm (Siracusa, Italy), were characterized: Bitter orange, “Femminello” lemon, Grapefruit, “Marzaiolo” mandarin, “Navelina” orange, “Ovale” orange, “Tarocco” orange and Clementine. For each species, 100 samples were selected and for each sample 5 measurements were made at different points. For colour specification the Commission Internationale de l'Eclairage (CIE) L*a*b* was used. From this data, the Chroma and Hue degree were calculated. For Raman characterization a portable instrumentation equipped with a 785 nm laser focused was used. All citrus fruits presented two strong intensity peaks at 1157 cm -1 and at 1526 cm -1 , except for grapefruit and “Femminello” lemon. The intensity ratio (R 1157/1526 ) between the two peaks was calculated and the related chromatic coordinates obtained from colour measurements taken in account. A predictive analytical model for the relation between chromatic caracteristics of citrus and functional carotenoids groups was found.