Abstract:
A procedure to maintain proper levels of oxygen and carbon dioxide inside a modified atmosphere package (MAP) that is exposed to two different temperatures was designed and tested. The design procedure involved first designing the MAP for a surrounding air atmosphere at the higher temperature, then selecting a surrounding controlled atmosphere (CA) environment to use at the lower temperature. Two series of tests involving strawberries and snap beans were conducted to show the feasibility of the procedure. These products were stored at 7°C for 4 days then 19°C for 2 days to simulate storage/shipment and retail display, respectively. Strawberries were stored in jars fitted with a short tube to regulate the flow of gases in and out of the jars. Snap beans were stored in commercially available, semipermeable plastic bags. The CA surrounding the MAP at 7°C helps to maintain the desired atmosphere inside the package by correcting for the change in product respiration rate due to the change in temperature. A computer program was developed to predict gas concentrations inside a MAP, the required surrounding atmosphere, and the film or tube permeability ratios to achieve proper gas levels in a package. The program was used to predict atmospheres within the strawberry and snap bean packages.
