Simultaneous measurement of oxygen and carbon dioxide diffusivities in pear fruit tissue using optical sensors

Knowledge of gas diffusion is important for understanding and developing controlled atmosphere treatments and modified atmosphere packaging for extended product life. Measuring gas diffusion properties of fruit tissue has proven difficult due to the available gas measurement techniques and the inherent biological variability of biological material as well as the fast deterioration and respiration activity of cut tissue samples. A measurement set-up for tissue diffusivities using fluorescent optical probes was developed. The optical sensors produced good informative O 2 and CO 2 partial pressure versus time profiles. Diffusivities of O 2 and CO 2 were estimated based on a finite element model describing simultaneous O 2 and CO 2 gas transport as well as respiration in the tissue. The average O 2 and CO 2 diffusivity of pear inner cortex tissue were (2.56±0.48)×10 -10 m 2 /s and (3.8±1.1)×10 -9 m 2 /s, respectively.