Mathematical modeling of gas concentration profiles in perforation-generated modified atmosphere bulk packaging
Emond, Jean Pierre
Thesis (Ph. D.) University of Florida , Gainesville, Florida, USA, 1992. 189 pages.
1992
บทคัดย่อ
Modified atmosphere packaging is a well-known postharvest technique to extend the shelf life of fresh fruits and vegetables. By lowering the oxygen concentration and increasing the carbon dioxide concentration inside the package, ripening and deteriorative processes, as well as growth of pathogens, may be reduced. Levels of O2 and CO2 achieved are functions of the product respiration rate, package gas permeability, and temperature. Modified atmosphere packaging is usually used for small quantities of produce. An interest toward modified atmosphere of large packages and pallet loads of produce necessitates a better understanding of the gas diffusion process inside the package.
Increasing the size of modified atmosphere packages may lead to significant gas concentration gradients within a package. No method is available for the prediction of the gas distribution inside bulk packages. Uneven gas distribution may shorten the shelf life of the product. There is considerable interest in developing a mathematical model that provides a better understanding of the three-dimensional gas distribution inside bulk packages. Such a model may be used to optimize bulk package designs.
In this study, a mathematical model was developed to predict the three-dimensional gas distribution as a function of time inside a modified atmosphere bulk package. The model takes into account gas diffusion, product respiration rates, package gas barrier properties, shape and size of the package, as well as the storage temperature.
Experiments to validate the mathematical model were performed with blueberries stored in a perforation-generated modified atmosphere bulk package. Very good agreement between experimental and simulation results was obtained for different types of packaging. Gas concentrations of O2 and CO2 varying from 8.5% to 14% and 7% to 13.5%, respectively, were observed in a one-meter-long package. Gas concentration profile inside the product layer was found to be insignificant.
Sensitivity analyses revealed that the gas concentration gradients inside a package increase proportionally to an increase of the package length. Simulations showed that an increase in the storage temperature can significantly increase the gas concentration profile and may expose products in certain regions to harmful conditions.