Quantitative determination of soluble solid content in bayberry juice using near-infrared spectroscopy technique

Near-infrared transmittance spectra of bayberry juice of different varieties in Zhejiang province were obtained and a quantitative analysis was carried out. Leverage value, studentized residue and sample's Mahalanobis distance were applied to detect the outlier sample, and different wave number ranges and resolutions were chosen for partial least squares (PLS) regression to abstract spectral information effectively. The,best factor, resolution and optimum wave number range were determined. Analysis results show that one sample was an outlier and deleted, and the best model gave the relative high correlation coefficient of 0.957 85, RMSEC, RMSEP and RMSECV of 0.431, 0.925 and 1.07 degrees Brix, respectively, when the best wave number range was 4000-12 267.46 cm(-1), and the best factor and resolution were 8 and 4 cm(-1), respectively. The results indicate that it is feasible to use NIR spectroscopy technique for quantitative analysis of bayberry juice soluble solid content.