A modified atmosphere system using a nitrogen generator

The generation of a stable modified atmosphere using a commercial oxygen scrubber (or N-2 generator), designed to store and transport palletised fruit and vegetables, was investigated. The target storage atmosphere was obtained in a two-step procedure. First, the pallet, placed in an air tight polyethylene casing, was flushed with a N-2-enriched gas mixture at the maximum flow rate that the generator could deliver to reduce the equilibration time. Second, the settings (total flow rate and percentage Of O-2) of the O-2 scrubber were changed according to calculations taking into account the physiological parameters of the plant tissues and the desired atmosphere at steady state. The process was tested at constant temperature on apples. In conditions of temperature abuse the system behaved like microperforated packaging, resulting in a marked deviation from the target atmosphere. The two main advantages of the system compared with conventional MAP are the possibility of generating any equilibrated atmosphere such as O-2 plus CO2 equal to or less than 21 kPa, and of enabling a manual correction if the storage temperature changes. The system is easy to handle (at stable temperatures) and does not involve any probes or fragile parts. (C) 2003 Elsevier B.V. All rights reserved.