Non-destructive measurement of acidity, soluble solids and firmness of Satsuma mandarin using Vis/NIR-spectroscopy techniques

Visible/near-infrared spectroscopy (Vis/NIRS) appears as a prominent technique for non-destructive fruit quality assessment. This research work was focused in to evaluate the use of Vis/NIRS in measuring the quality characteristics of intact Satsuma mandarin Zaojin Jiaogan (C reticulata), and to establish the relationship between non-destructive Vis/NIR spectral measurements and the major physiological properties of fruit (firmness, soluble solids content (SSC) and acidity (pH)). Before calibration, two types of data pre-processing were used and NIR models were developed based on partial least square (PLS) and principal component regression (PCR) techniques. The prediction models indicated that a reasonable to excellent prediction performance could be expected for each property. The best SSC model had a mean square error of prediction (RMSEP) of 0.33 degrees Brix and correlation coefficient between predicted and measured values (r) of 0.94, the proposed model for the pH and the compression force had a RMSEP of 0.18 and 8.53, as well as, r of 0.8 and 0.83, respectively. It was concluded that by using the Vis/NIRS measurement technique, in the full spectral range (400-2350 nm), it is possible to assess the quality characteristics of mandarin. (c) 2005 Elsevier Ltd. All rights reserved.