Optical properties and Monte Carlo multi-layered simulation of potato skin and flesh tissues

The study of optical properties of potato plays an essential role in optimizing the application of visible nearinfrared (VIS-NIR) spectroscopy for nondestructive testing. This study aimed to investigate the propagation pattern of light in potato tissues and determine the depth of light penetration via a five-layer Monte Carlo simulation. A VIS-NIR integrating sphere system was used to measure the reflectance and transmittance of potato tissues in the range of 550 - 1850 nm. The absorption coefficient ia and the reduced scattering coefficient ifs were calculated using the inverse adding-doubling (IAD) method. The results demonstrated that the difference in ia between the potato skin and flesh tissues was not significant, whereas the difference in ifs was significant. The different microstructures of the potato skin and flesh tissues led to the significant difference in ifs. The results of Monte Carlo multi-layered simulations revealed that light had low reflectivity, high absorbance, and zero transmittance when propagating through the five-layer potato tissue. The wavelengths with highest and lowest absorbance were found to be 1451 and 891 nm, respectively. According to convolution (CONV) calculation results, the penetration depth of light in potato tissue was about 5.5 - 10.6 mm and the diffusion radius was 6.64 - 8.68 mm. This study provided a more accurate and usable sampling area for reflectance measurements using VIS-NIR spectroscopy. The findings of this study provided a reference for more refined non-destructive testing methods for potatoes.