Non-destructive evaluation of orange juice based on optical scattering intensities

Optical scattering spectra and angular distribution of scattering intensities were evaluated using concentrated orange juice. The concentrated orange juice was opaque due to the scattering particles included. In these specimens, the scattering intensities and angular distribution of the scattering intensities varies with the refractive index ratio of the scattering particles against the liquid surrounding the particles. The sugar concentrations of orange juice, which are linearly correlated with the refractive index of the specimens, can therefore be measured by the scattering intensities and their angular distributions. The scattering intensities measured using a halogen lamp, a white LED, a yellow LED, a red LED and near-infrared LEDs (λ = 850 nm and 940 nm) vary linearly with the sugar concentrations of the specimens. The gradient and correlation coefficient of the calibration lines fitted are found to vary with the scattering angles, θ. A non-destructive evaluation of the sugar concentrations of orange juice can be measured sensitively at θ = 170 or 160 °s with any incident lights which are scattered from the specimens.