Optical scattering from tomato juice

Optical scattering spectra and angular distribution of scattering intensities were evaluated using commercially available tomato juice for a non-destructive quality control. A halogen lamp, a red LED and NIR LEDs (λ = 850 nm and λ = 940 nm) can be used as the incident light for scattering evaluations of tomato because incident light with wavelengths shorter than 550 nm is absorbed by pigments in tomato. Scattering intensities and their angular distributions are found to depend on the sugar concentrations of tomato juice. The scattering intensities vary linearly with the sugar concentrations of the specimens irradiated with a halogen lamp, a red LED or NIR LEDs (λ = 850 nm and λ = 940 nm). Gradient of calibration lines, G, between the sugar concentrations and the scattering intensities varies with the scattering angles and the wavelength of light irradiated. G is large negative value with large scattering angles such as a back scattering configuration. While, G is small positive value with small scattering angles such as a forward scattering configuration.