Articles
A technique to map oxygen diffusivity in fruit and vegetable organs
Article number
1386_45
Pages
331 – 338
Language
English
Abstract
Oxygen (O2) diffusion in a horticultural product is a microstructure-dependent process affecting the respiratory metabolism.
As the porosity of the tissue varies across the product, it is likely that the effective O2 diffusivity is heterogeneous at different tissue positions.
This study aims to develop a technique to construct a 3-D O2 diffusivity map based on X-ray computed tomography (CT) images.
A correlation model of effective O2 diffusivity and total tissue porosity was developed for four different tissues: eggplant, turnip, apple and pear.
As a comparison, distribution of the O2 diffusivity versus open porosity of the same tissues was also investigated.
Open porosity is a measure of the volume fraction of connected pores promoting diffusion of oxygen.
The model prediction of diffusivity with respect to total porosity had an RMSE=6.92 10‑7 m2 s‑1 and R2=0.92, but better result was obtained with a model with respect to open porosity with the RMSE=5.45 10‑7 m2 s‑1 and R2=0.95. Since the total tissue porosity could be easily and accurately generated from grayscale CT image, mapping of O2 diffusivity was performed with respect to the total porosity map.
However, distribution of O2 diffusivity in apple was mapped with respect to open porosity due to less opened pore structure of apple.
Open porosity map was estimated from a correlation between total-open porosity difference and total porosity with RMSE=4.27 and R2=0.49. This approach resulted a closer agreement between predicted and observed O2 diffusivity validated along the radial tissue sample.
The mapping technique successfully showed the spatial variation of effective O2 diffusivity in the entire product organ.
As the porosity of the tissue varies across the product, it is likely that the effective O2 diffusivity is heterogeneous at different tissue positions.
This study aims to develop a technique to construct a 3-D O2 diffusivity map based on X-ray computed tomography (CT) images.
A correlation model of effective O2 diffusivity and total tissue porosity was developed for four different tissues: eggplant, turnip, apple and pear.
As a comparison, distribution of the O2 diffusivity versus open porosity of the same tissues was also investigated.
Open porosity is a measure of the volume fraction of connected pores promoting diffusion of oxygen.
The model prediction of diffusivity with respect to total porosity had an RMSE=6.92 10‑7 m2 s‑1 and R2=0.92, but better result was obtained with a model with respect to open porosity with the RMSE=5.45 10‑7 m2 s‑1 and R2=0.95. Since the total tissue porosity could be easily and accurately generated from grayscale CT image, mapping of O2 diffusivity was performed with respect to the total porosity map.
However, distribution of O2 diffusivity in apple was mapped with respect to open porosity due to less opened pore structure of apple.
Open porosity map was estimated from a correlation between total-open porosity difference and total porosity with RMSE=4.27 and R2=0.49. This approach resulted a closer agreement between predicted and observed O2 diffusivity validated along the radial tissue sample.
The mapping technique successfully showed the spatial variation of effective O2 diffusivity in the entire product organ.
Authors
B. Nugraha, P. Verboven, S. Janssen, B.M. Nicolaï
Keywords
X-ray computed tomography, tissue microstructure, eggplant, turnip, apple, pear
Online Articles (51)