Diffusion channels for broccoli storage

This thesis focuses on diffusion channel design for broccoli storage, an important cash crop and consumer commodity in Canada. Experiments were first conducted to determine the respiration rate of broccoli in modified atmosphere conditions created by the produce metabolic activity inside closed chambers, at four different temperatures in the cold room of 3, 7, 13, and 24$ sp circ$C. The respiration rate decreased with a reduction of O$ sb2$ concentration inside the chamber. A model to predict the respiration rate of broccoli as a function of O$ sb2$ concentration at different temperatures was developed. Experiments were then carried out to determine the cross sectional area and length of diffusion channel leading to various final O$ sb2$ (steady-state) concentrations during the storage of broccoli. Combinations of cross sectional area of 0.04, 0.18, and 1.15 cm$ sp2$ and length of 0.6, 3, 7, 12, 18, and 25 cm were tested. The carbon dioxide produced through respiratory process was absorbed by placing hydrated lime inside the chambers such that the two-component molecular diffusion model by Ratti et al. (1993) could be evaluated. The length and cross sectional area of diffusion channel have a significant effect on the final level of O$ sb2$ (steady-state) concentration. The Ratti model then served as a basis for a modified model for predicting the length of diffusion channel required to obtain a given O$ sb2$ concentration as a function of the mass of stored broccoli and the cross sectional area of the diffusion channel. (Abstract shortened by UMI.