Prediction Equations for Gases in Flexible Modified‐Atmosphere Packages of Respiring Produce are Different Than Those for Rigid Packages

Total pressure generally decreases in a sealed rigid package containing respiring produce, whereas total pressure is essentially constant and free volume decreases in a flexible package. We found that predicted O 2 , CO 2 , and N 2 partial pressures were different for similarly designed (same surface area, thickness, film permeabilities and produce mass) flexible and rigid packages at “quasi steady state” and steady state, respectively. Predicted O 2 and CO 2 partial pressures were slightly higher in a flexible package than in a rigid package and were a function of the film permeability ratio of N 2 to O 2 and of CO 2 to O 2 . They also related to the ratio of product CO 2 production rate to O 2 uptake rate, target steady‐state O 2 partial pressure, and respiration characteristics. Differences were slight for films such as low‐density polyethylene.