Packaging for use with UV-C
To achieve optimum microbial reductions for in-package UV treatment, it is necessary to select a highly transmissive packaging material.
Material that is transparent to visible light may not be transparent to UV-C light. Opaque components such as labels or printed inks should also be avoided as they may create shadowed areas on the pakaged product, areas in which UV-C light does not contact and therefore does not incactivate any microorganims.
Transmissivity of UV light
The UV-C transmissivity of packaging materials is dependant on several factors such as the material thickness, composistion if multi-layered, additives and adhesives that may be in the packaging, and crystallinity. Examples of UV transmission through some common packaing materials is shown in the Table 1(Tarek, et, al., 2015).
The table below shows transmissivity of UV light through various films. "a" and "b" denote different suppliers.
|
Film |
Composition |
Thickness (μm) |
Transmissivity (%) |
|
PEa |
|
24.7 |
75.7 |
|
PETa |
|
14.2 |
0.0 |
|
PPa |
|
29.5 |
59.4 |
|
OPPb |
PP/Adhesive |
18.7 |
57.9 |
|
PETb |
|
14.2 |
0.0 |
|
CPPb |
Adhesive/PP/Adhesive |
33.0 |
56.0 |
|
PEb |
|
30.0 |
53.7 |
Criteria for packaging choice
In addition, UV-C light may cause changes in the chemical and mechanical properties of polymer films through photochemical reactions that may impact the food product.
The legislation in the European Union requires that no substance may migrate into the food product in concentrations that can be considered harmful to human health (Europena Union, 2004). These photochemical reactions may influence the integrity of the packaging in undesirable ways, such the strength, or possible discolouration or cracking that may appear (Heinrich, et. al., 2015), and should be considered in package selection and safety assessment.
Sources:
Europian Union, 2004. Regulation (EC) No 1935/2004 OF THE EUROPEAN PARLIMENT AND OF THE COUNCIL of 27 October 2004 on materials and articles intended to come into contact with food and repealing Directives 80/590/EEC and 89/109/EEC. Official Journal of the European Union, 4-17.
Heinrich, V., Zunabovic, M., Bergmair, J., Kniefel, W. and Jäger, H. (2015) Post-Packaging Application of Pulsed Light for Microbial Decontamination of Solid Foods: A Review. Innovative Food Science and Emerging Technologies, 30, 145-156.
Tarek, A.R., Rasco, B.A. and Sablani, S.S. (2015) Ultraviolet-C Light Inactivation Kineticsof E. coli on Bologna Beef Packaged in Plastic Films. Food Bioprocess Technology, 8(6), 1267-1280.
