Nondestructive Measurement of the Internal Quality of Bayberry Juice Using NIR Spectroscopy

A nondestructive optical method for determining the sugar and acidity contents of bayberry juice was investigated. Two types of preprocessing were used before the data were analyzed with multivariate calibration methods of PLS. Spectral data set as the logarithms of the reflectance reciprocal were analyzed to build a best model for predicting the sugar and acidity contents of bayberry juice. A model with a correlation coefficient of 0.86/0.92, a standard error of prediction (SEP) of 0.51/0.19 and a bias of 0.06/-0.13 showed an excellent prediction performance to sugar content or acidity. At the same time, the correlation between bayberry juice and absorbance across the entire spectral region from 400nm and 1000nm was also analyzed. The result showed that no single wavelengths were strongly correlated with sugar content or acidity which suggested the necessity to use a wider range of spectrum than selected wavelengths to predict sugar content or acidity of bayberry juice