title: Mixture resolution according to the percentage of robusta variety in order to detect adulteration in roasted coffee by near infrared spectroscopy.
abstract: Near infrared spectroscopy (NIRS), combined with multivariate calibration methods, has been used to quantify the robusta variety content of roasted coffee samples, as a means for controlling and avoiding coffee adulteration, which is a very important issue taking into account the great variability of the final sale price depending on coffee varietal origin. In pursuit of this aim, PLS regression and a wavelet-based pre-processing method that we have recently developed called OWAVEC were applied, in order to simultaneously operate two crucial pre-processing steps in multivariate calibration: signal correction and data compression. Several pre-processing methods (mean centering, first derivative and two orthogonal signal correction methods, OSC and DOSC) were additionally applied in order to find calibration models with as best a predictive ability as possible and to evaluate the performance of the OWAVEC method, comparing the respective quality of the different regression models constructed. The calibration model developed after pre-processing derivative spectra by OWAVEC provided high quality results (0.79% RMSEP), the percentage of robusta variety being predicted with a reliability notably better than that associated with the models constructed from raw spectra and also from data corrected by other orthogonal signal correction methods, and showing a higher model simplicity.
authors: Department of Chemistry, University of La Rioja, C/Madre de Dios 51, 26006 Logroño (La Rioja), Spain. consuelo.pizarro@dq.unirioja.es <consuelo.pizarro@dq.unirioja.es>
authors: C
authors: C
authors: Pizarro
authors: I
authors: I
authors: Esteban-Díez
authors: J M
authors: JM
authors: González-Sáiz
mesh_terms: D000465:Algorithms; D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000379:methods; D003069:Coffee; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination; D007700:Kinetics; D008962:Models, Theoretical; D015999:Multivariate Analysis; D012044:Regression Analysis; D015203:Reproducibility of Results; D012984:Software; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013997:Time Factors
chemical_list: D003069:Coffee