title: Feasible application of a portable NIR-AOTF tool for on-field prediction of phenolic compounds during the ripening of olives for oil production.
abstract: Olive fruits of three different cultivars (Moraiolo, Dolce di Andria, and Nocellara Etnea) were monitored during ripening up to harvest, and specific and total phenols were measured by HPLC (High Pressure Liquid Chromatography). On the same olive samples (n = 450), spectral detections were performed using a portable NIR (Near Infrared)-AOTF (Acousto Optically Tunable Filter) device in diffuse reflectance mode (1100-2300 nm). Prediction models were developed for the main phenolic compounds (e.g., oleuropein, verbascoside, and 3,4-DHPEA-EDA) and total phenols using Partial Least Squares (PLS). Internal cross-validation (leave-one-out method) was applied for calibration and prediction models developed on the data sets relative to each single cultivar. Validation of the models obtained as the sum of the three sample sets (total phenols, n = 162; verbascoside, n = 162; oleuropein, n = 148; 3,4-DHPEA-EDA, n = 162) were performed by external sets of data. Obtained results in term of R(2) (in calibration, prediction and cross-validation) ranged between 0.930 and 0.998, 0.874-0.942, and 0.837-0.992, respectively. Standard errors in calibration (RMSEC), cross-validation (RMSECV), and prediction (RMSEP) were calculated obtaining minimum error in prediction of 0.68 and maximum of 6.33 mg/g. RPD ratios (SD/SECV) were also calculated as references of the model effectiveness. This work shows how NIR-AOTF can be considered a feasible tool for the on-field and nondestructive measurement of specific and total phenols in olives for oil production.
authors.affiliation: Department for Innovation in Biological Agro-food and Forest systems (DIBAF)-Postharvest Laboratory, University of Tuscia, Viterbo, Italy. bellin@unitus.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Bellincontro
authors.forename: Agnese
authors.initials: A
authors.lastname: Taticchi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Servili
authors.forename: Sonia
authors.initials: S
authors.lastname: Esposto
authors.forename: Daniela
authors.initials: D
authors.lastname: Farinelli
authors.forename: Fabio
authors.initials: F
authors.lastname: Mencarelli
mesh_terms: D031658:Olea / Q000737:chemistry* / Q000254:growth & development; D000069463:Olive Oil; D010636:Phenols / Q000032:analysis*; D010938:Plant Oils / Q000032:analysis*; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods*
chemical_list: D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils