Simultaneous determination of oxygen diffusivity and respiration in pear skin and tissue

A novel method to measure gas diffusion properties of pear tissue and skin was developed. In a temperature and pressure controlled system, a diffusion cell was attached to a polarographic oxygen electrode to measure gas diffusivity. A dynamic finite element model based on simultaneous gas diffusion and respiration for pear slices and pear skin was developed. The average experimentally determined values for oxygen diffusivity in tissue and skin were, respectively, 1.71 x 10(-9) m(2) s(-1) and 2.84 x 10(-10) m(2) s(-1). The mean estimated tissue and skin respiration values did not differ statistically, at a 5% level of significance, from the mean respiration values obtained in an independent traditional respiration experiment. If the oxygen consumption and the oxygen diffusivity needed to be estimated accurately and simultaneously from one experiment, the experiment typically lasted 15 h. The duration of the diffusion measurement could be reduced to 3 h, when the respiration characteristics were measured in a separate experiment. Monte-Carlo simulations were performed to calculate the variability due to biological variation of oxygen transport and consumption in slices of pear tissue covered with skin. (C) 2001 Elsevier Science B.V. All rights reserved.