Non‐destructive measurement of pear internal quality indices by visible and near‐infrared spectrometric techniques

The feasibility of non‐destructive measurement of internal quality indices of intact pear fruit using visible and near‐infrared (Vis/NIR) spectrometric techniques was studied. In the wavelength region from 350 to 1800 nm, calibration models relating Vis/NIR spectra to soluble solids content (SSC) and firmness were developed based on multilinear regression (MLR), principal component regression (PCR) and partial least squares regression (PLSR) with respect to the logarithms of the reflectance reciprocal log (1/R), its first derivative D 1 log (1/R) and its second derivative D 2 log (1/R). The best combination, based on the reliable and robust models obtained, was the PLS models with respect to log (1/R) at an equatorial position of the fruit. Prediction with the PLS model with respect to log (1/R) resulted in correlation coefficients ( r p ) of 0.9121 and 0.8541, and root mean standard error of prediction (RMSEP) of 0.6619 and 1.2324 for SSC and firmness, respectively. The experimental results indicate that the Vis/NIR spectrometric technique could provide an accurate, reliable and non‐destructive method for assessing internal quality indices of pear fruit, especially for SSC.