Non-invasive measurements of the internal quality of intact 'Gannan' navel orange by VIS/NIR spectroscopy.

摘要

Estimation of the soluble solids content (SSC), titratable acidity (TA) and available acidity (pH) of cv. Gannan navel oranges using visible and NIR (VIS/NIR) spectroscopy is described. VIS/NIR spectra were acquired using a custom-designed, contact optical-fibre probe and recorded in transmission mode. Calibration models relating the VIS/NIR spectra to SSC, TA and pH were developed based on 2 different regression methods, partial least square (PLS) regression and principal component regression (PCR), with respect to percentage transmission (%T) spectra data and 1st- and 2nd-derivative spectra. The prediction performance of the calibration models in different wavelength regions was also investigated. The best models were based on PLS regression methods with root mean s.e. of validation (RMSEP) of 0.464 degrees Brix, 0.704 g l-1 and 0.125, and correlation coeff. (r2) of 0.804, 0.643 and 0.651 for SSC, TA and pH, respectively. Results suggest that VIS/NIR spectroscopy may be a reliable, accurate and fast method for non-invasive measurements of navel orange SSC and acidity.