Visible and near infrared spectroscopy for rapid analysis of the sugar composition of raw ume juice

Abstract

Visible and near infrared spectroscopy was investigated as a method for rapid analysis of the sugar compositions of raw ume juice. In total, 314 raw ume juice samples were collected over a long growth period and visible and near infrared transmittance spectra between 400 and 1850 nm were acquired using a spectrophotometer with a quartz cuvette with 1-mm thickness. The partial least squares (PLS) calibration models for the total sugar content of ume fruit juice were developed using original spectra and pretreated spectra (normalization, first derivative, second derivative and multiplicative scatter correction) in five different wavelength ranges. The best models used the second derivative spectral data in the wavelength ranges of 1100-1850 nm with the lowest standard error of prediction (0.133%). Moreover, good calibration models for sugar compositions (fructose, glucose, sorbitol, sucrose) of ume juice were obtained using the same second derivative spectral data in the wavelength range of 1100-1850 nm, and gave relatively good predictions with high value of R 2 and low value of SEP: fructose, 0.96 and 0.062%; glucose, 0.94 and 0.068%, sucrose, 0.92 and 0.065%, sorbitol, 0.87 and 0.046, respectively. Results indicated that near infrared spectroscopy provided useful method to rapidly analyze the total sugar content and the sugar composition of raw Ume fruit juice.