Bulk optical of potato flesh in the 500 – 1900 nm range

This is a post-peer-review, pre-copyedit version of an article published in Food and Bioprocess Technology. The final authenticated version is available online at: https://doi.org/10.1007/s11947-015-1639-0 In this study, the optical properties of potato flesh tissue were estimated using double-integrating sphere (DIS) measurements combined with an inverse adding-doubling (IAD) light propagation model. Total reflectance, total transmittance, and unscattered transmittance were measured for the wavelength range 500– 1900 nm with 5-nm resolution. From these measurements, the bulk optical properties (absorption coefficient, scattering coefficient, and anisotropy factor) of 53 potato tubers of the Hermes cultivar were estimated. The estimated absorption coefficient spectra were dominated by water and starch absorption bands, the main chemical components of potato tissue. Comparison of these values to those reported in literature for similar products showed comparable absorption profiles. The obtained scattering coefficient spectra showed a smooth decrease from 166 to 160 cm−1 in the near-infrared (NIR) spectral range with increasing wavelength, which is common for biological tissues. The anisotropy factor spectra obtained for the full wavelength range studied ranged between 0.949 and 0.959 with a maximum variability of 0.009 among the set of samples used. The information obtained in this study is essential to understand the effects of absorption and scattering on the propagation of light through the potato tubers in order to design more efficient sensors for non-destructive quality evaluation. The funding of this work has been covered by the Universidad Pública de Navarra through the concession of both a predoctoral research grant and a mobility grant, by the National Institute for Agricultural and Food Research and Technology (INIA) project: BGenetic improvement of Potato. Characterization of the material by NIRS technology^ RTA 2011-00018-C03-03, and by the Agency for Innovation by Science and Technology in Flanders (IWT) through the Chameleon (SB-100021) project.