Simultaneous measurement of brown core and soluble solids content in pear by on-line visible and near infrared spectroscopy

• Yali pear quality was measured online by vis–NIR spectroscopy.
• Browning and soluble solids (SSC) of pears were detected simultaneously.
• Accuracy of discrimination model for browning based on wavelength ratios was 98.3%.
• Standard error of prediction model for SSC was 0.35%.

The feasibility of brown core and soluble solids content (SSC) simultaneously online by visible and near infrared (visible–NIR) transmittance spectroscopy. Visible–NIR spectra of brown core and sound pears were recorded at a moving speed of five samples per second. Different combinations of two wavelengths were searched by correlation analysis in the wavelength range of 600–904 nm to discriminate brown core and sound pears. Partial least squares (PLS) regression models calibrated with sound samples yielded better results then PLS models built with brown core pears and the combinations of brown core and sound ones. Then a novel strategy was proposed for simultaneous measuring brown core and SSC by on-line visible and NIR spectroscopy. The new samples, including 8 brown core pears and 32 sound ones, were applied to evaluate the performance of the classification and quantitative analysis models. The classification accuracy of brown core pears was 98.3%. The percentages of SSC predictive precision were 97.8% and 99% within deviations of ±0.5 and ±1%, respectively. The results suggested that classification using two wavelengths and quantitative analysis using PLS were suitable to measure brown core and SSC of pears simultaneously by on-line visible and NIR spectroscopy.