Simultaneous and non-destructive fungicide identification and storage monitoring of Shatangju mandarin with near-infrared spectroscopy and chemometrics

Simultaneous and non-destructive fungicide identification and storage monitoring of Shatangju mandarin were achieved based on portable near-infrared (NIR) spectroscopy with chemometrics. 300 Shatangju mandarin samples after dipping with different concentrations of imazalil (IMZ) were collected, and the NIR spectra at three integration times during fruit storage were obtained. The fungicide identification and storage monitoring models were established with the pattern recognition and variable screening techniques. The results indicated that 100 % fungicide identification accuracy can be obtained with the variable screening strategy. Increasing the integration time could improve the identification results, while longwave NIR spectral region was suitable for the fungicide identification. The NIR spectra were arranged sequentially in the principal component dimension with the increase of storage days. Significant changes in fruit compositions occurred in the first 6 days, while more rotten fruits appeared after 12 days. The coefficients of determination in cross-validation (Rs 2 ) obtained for the prediction of storage days were above 0.94, showing the potential of NIR spectroscopy to identify the time of storage. Simultaneous and non-destructive fungicide identification and storage monitoring of Shatangju mandarin were achieved based on the portable near-infrared spectroscopy with chemometrics. • Simultaneous IMZ identification and storage monitoring were achieved. • Increasing the integration time can improve the PLS-DA identification model. • Variable screening strategy can simplify the models with 100 % accuracy. • Prediction of storage days was achieved with NIR spectroscopy and PLS. • Key wavelength points that cause spectral changes were obtained during storage.