MODELING FREQUENCY-DISTRIBUTION OF STEADY-STATE O-2 PARTIAL PRESSURESIN MODIFIED-ATMOSPHERE PACKAGES

A mathematical model was developed to predict the frequency distributi on of steady-state O-2 partial pressures in modified-atmosphere packag es of fresh and minimally processed fruits and vegetables. Variation i n O-2 uptake was predicted to have relatively larger influence on the package O-2 distribution than variation in film permeability to O-2. T he model also predicted that the range of O-2 partial pressures in the packages would be larger for the products with lower K-1/2 (a constan t in product O-2 uptake equation) values. The percent deviation of pac kage O-2 partial pressures from [O-2](med) increased with [O-2](med) u p to about 3 kPa and gradually decreased thereafter. Package O-2 distr ibution was symmetrical at higher [O-2](med) but became gradually asym metrical with decreasing [O-2](med) from 6 kPa. The model was used to predict target [O-2](med) for the design of modified-atmosphere packag es for different probability levels of having package O-2 being equal to or less than a minimum tolerable level of the product.