A protective atmosphere in a flexible packaging can change its composi
tion by means of gases interactions with the food components or gases
diffusion through the container. Such diffusion corresponds both to pe
rmeability phenomena and to unselective diffusion through leaks in the
material or package. While this last phenomenon can not be Foreseen i
n any way, as it is completely occasional, permeability is largely pre
dictable by the diffusional properties of the materials and internal a
tmosphere composition. In this work a computing procedure is proposed,
which allows to predict the atmosphere evolution only on the basis of
permeability phenomena, and are presented the tests that were carried
out to verify its reliability. The gaschromatographic analysis of the
atmosphere changes, measured in packages closed with different gas co
mpositions and produced with different materials and geometry, demonst
rated the effectiveness of the iterative computing procedure suggested
, which could represent an useful tool for optimising the package desi
gn in order to reach the best results in protective atmosphere packagi
ng technology.