title: Oil accumulation in intact olive fruits measured by near infrared spectroscopy-acousto-optically tunable filter.
abstract: BACKGROUND
  A field experiment was conducted to test the reliability of the near infrared spectroscopy (NIR)-acousto-optically tunable filter (AOTF) method to measure mesocarp oil content in vivo against nuclear magnetic resonance (NMR) determinations using three different olive cultivars at different stages of ripening.
  
  
  RESULTS
  In the partial least squares model carried out for the cultivar 'Arbequina', the coefficient of determination in calibration (R(2)c) was 0.991, while the coefficient of determination in cross-validation (R(2)cv) was 0.979. For the cultivar 'Frantoio' the indexes were 0.982 and 0.971, respectively; while for the cultivar 'Leccino' R(2)c was 0.977 and R(2)cv was 0.965. Finally, for the combined model (sum of the three varieties) these indexes were 0.921 and 0.903, respectively. The residual predictive deviation (RPD) ratio was insufficient for the predictive model of cultivar 'Leccino' only (1.98), whereas in the other cases the RPD ratios were completely sufficient, within the estimation range over 2.5-3 (2.61 in the global model, and 4.23 in the cultivar 'Frantoio'), or in describing a large capacity with values greater than 5, as in the cultivar 'Arbequina' (9.58).
  
  
  CONCLUSIONS
  NIR-AOTF spectroscopy proved to be a novel, rapid and reliable method to monitor the oil accumulation process in intact olive fruits in the field. The innovative approach of coupling NIR and NMR technologies opens up new scenarios for determining the optimal time for harvesting olive trees to obtain maximum oil production.
authors.affiliation: Department Innovazione dei Sistemi Biologici, Agro-alimentari e Forestali, University of Tuscia, Viterbo, Italy. bellin@unitus.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Bellincontro
authors.forename: Giovanni
authors.initials: G
authors.lastname: Caruso
authors.forename: Fabio
authors.initials: F
authors.lastname: Mencarelli
authors.forename: Riccardo
authors.initials: R
authors.lastname: Gucci
mesh_terms: D000162:Acoustics; D002138:Calibration; D005638:Fruit / Q000737:chemistry* / Q000378:metabolism; D016018:Least-Squares Analysis; D009682:Magnetic Resonance Spectroscopy; D031658:Olea / Q000737:chemistry* / Q000378:metabolism; D000069463:Olive Oil; D055095:Optics and Photonics; D010938:Plant Oils / Q000032:analysis* / Q000378:metabolism; D015203:Reproducibility of Results; D013045:Species Specificity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D000069463:Olive Oil; D010938:Plant Oils