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Optimization of the gas permeability of thermoformed packaging by selection of materials, process parameters and design (R-4480)

To maintain organoleptic and nutritional quality and microbial safety of a food product, packaging must guarantee an optimal gas barrier, e.g. for oxygen, carbon dioxide and/or water vapor, and this at the desired temperature and relative humidity (RH). Often companies use the oxygen transmission rate (OTR) of the flat film also for the thermoformed packaging. This is however an overestimate of the actual gas barrier of the packaging! In a recent Flanders'Food (FF) project (MaProDe_Ox), the impact of materials, processing and design on the oxygen permeability of thermoformed trays was examined in collaboration with companies from the Belgian Food and Packaging industry. In this study, 7 commercial packaging materials were thermoformed into trays with 2 or 3 uncomplicated designs (only variation in depth and radius of the corners) and this for two thicknesses of each material. The results give a qualitative and quantitative insight into the change of the oxygen permeability as a result of the combined effects of physical stretching, material thinning in corners and walls and potential re-orientation of the polymer molecules during the thermoforming process. This TETRA project includes new research questions, focusing on deepening the trends found in the FF project and focusing on new aspects in the field of material, process and design of thermoformed packaging. In terms of design, the aim is to further translate the OTR data of the sheets, into more complex, real trays with ribs and/or specific bottoms. New in this study is the inclusion of a biomaterial in addition to conventional plastics; mapping of additives with potential impact on the OTR; quantifying the effect of a heat treatment on the OTR of selected trays; and review of the trends found by means of case studies. For an improved and more uniform understanding of the relationship between the process parameters and the gas permeability, this project wants to develop a method that relates data from thickness measurements, orientation and crystallization and understanding of stress lines to each other. In this way, a prediction should be formulated concerning the gas permeability of the thermoformed tray. Given that the research topic of gas permeability of thermoformed packaging is very close to practical and commercial considerations of companies that develop, produce, characterize and distribute materials and packaging for the food industry, as well as food companies that use thermoformed packaging to ensure the shelf life of their products and to influence the marketing of their products, a direct application and validation of the results for the industrial partners is expected.
Date:1 Mar 2013 →  30 Apr 2015
Keywords:gaspermeability, oxygen transmission rate, thermoformed trays
Disciplines:Chemical sciences, Pharmaceutical sciences