Influence of surface curvature on light-based nondestructive measurement of stone fruit

•Intact stone fruit were modeled as concentric-spherical-layered tissues.•Light propagation in fruit was simulated using Monte Carlo methods.•Surface curvature affects the diffuse reflectance and the inspection efficiency.•The experimental arrangements require adjustment accordingly.

The propagation of photons in stone fruit tissue was simulated with the Monte Carlo (MC) method. A model of concentric-spherical-layered tissues was built for intact stone fruit. Peaches were used as typical representatives of stone fruit. Diffuse reflectance and inspection efficiency were calculated using the concentric-spherical-layered model. The simulation results were compared with those expected from the classic infinitely-wide planar layered model. Surface curvature increases the diffuse reflectance but decreases the inspection efficiency, especially for the case of short source-detector distance. For small size fruit items, errors in the planar layered tissues model would be increased due to their greater surface curvature. This paper suggests a need to take into account the influence of surface curvature to retrieve the optical absorption and reduced scattering coefficients from Vis-NIR spectroscopy data for fruit. And the experimental arrangements such as the source-detector distance and the integration time for the spectrometer require adjustment accordingly.

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