EVALUATION OF PHOTON MIGRATION AND LASER-INDUCED BACKSCATTERING IN KIWIFRUIT

Kiwifruit (Actinidia deliciosa) of selected commercial grades and randomly selected pieces in the retail were analyzed. Laser diodes emitting at 670 nm targeting mainly the influence of chlorophyll absorption as well as the scattering, and 785 nm addressing the impact of fruit scattering properties on the photon migration in the fruit tissue were applied. Digital images of 768x576 pixel size were captured and processed. Intensity values of the backscattering area were corrected with Lambertian cosine law taking the elliptic shape into account. Twenty-three optical parameters were calculated from the logistic intensity gradients in radial directions and forwarded to statistical analysis. Discriminant analysis, with leave-one-out cross validation, resulted in 83.68% correct classification of commercial grades and 74.17% correct identification of bruised pieces.