Packaging materials for high pressure thermal sterilisation
- How does it work?
- What can it be used for?
- What can it not be used for?
- Related Facilities
- Further Information
|Key words||High pressure sterilisation, packaging material, multilayer film, barrier|
How does it work?
|Primary objective||Packaging material which is resistant to the specific conditions of high pressure thermal sterilisation (high pressure and temperature)|
|Working principle|| High pressure thermal sterilisation is a novel preservation process where the packaged food and chamber is preheated to temperatures between 60 and 90°C. Temperatures can reach 90°C to 130°C during compression at pressures of 600 MPa or greater. The integrity of the packaging materials during this process is of critical importance to the safety and shelf life of the food product. Only a few packaging materials (namely nylon, EVOH, PET, PP, aluminum oxide (AlOx) coating, and Al or metalized layer ) can survive this process. Several multilayered films produced from these materials are commercially available and have been characterized and evaluated for suitability to the high pressure thermal sterilisation.
Another aspect to consider about a packaging material is its behavior as a barrier to heat. The headspace left inside the package as well as internal stresses from the vacuum created are additional factors that affects heat and mass transfer. During preheating and cooling steps, the packaging material constitutes an intermediate barrier in the transfer of heat from the heating medium into the product and from the product to the cooling medium. During the pressurization stage, packaging material such as polypropylene has been shown to act as an insulating barrier. It prevents heat loss from the product and slows down the heating rate of the product .
High pressure thermal sterilisation increases the seal strength of foil-laminated pouches. However it does not significantly contribute to changes in seal strength of plastic-laminated pouches. It can alter also the oxygen barrier of the composite packaging materials [1, 2, 3, 4, 5, 7].
|Additional effects||Possibility of migration and scalping effect for some compounds (e.g. aroma compounds- 2-hexanone, ethyl butanoate, ethyl hexanoate, d-limonene) and materials (low density polyethylene (LDPE), polylactate (PLA)) [8, 9]|
|Important process parameters|| temperature, pressure
Packaging conditions: headspace left inside the package, internal stresses after the vacuum packaging
|Important product parameters|| thermal diffusivity, thickness, seal strength, overall integrity, oxygen permeability and water vapour, max. temperature, light permeability for light sensitive products
The thickness of the material, as well as its thermal diffusivity, can affect the rate of heat conduction to (or from) the product during preheating (or cooling).
What can it be used for?
|Products||All products which can be processed by high pressure thermal sterilisation ( none commercially thus far)|
|Operations||Packaging of products|
|Solutions for short comings||There is a need for materials with good barrier and mechanical properties for high pressure thermal sterilisation|
What can it NOT be used for?
|Products||Products with sharp shape which can damage the packaging material|
|Other limitations|| Some type of packaging foil materials can separate or delaminate under temperature or pressure stress (e.g. between the PP and Al layers);
they can also partly loose its oxygen barrier ability . Increasing of gas permeability can be caused by thermal damage occurring during preheating 
|Risks or hazards||There is a possible risk for migration of compounds from the packaging material (e.g. alkanes, alkenes, benzene compounds etc.).|
|Maturity||There exist some packaging materials which have been tested for high pressure thermal sterilisation. New types of packaging materials with better properties are still developed. The high pressure thermal sterilisation operation itself is not mature and still under development.|
|Modularity /Implementation||Special type of heat seal vacuum equipment is required for closing of some pouches|
|Consumer aspects||There is a growing demand for safer food products of higher quality. The packaging material (delamination etc.) plays also a major role for the appearance of the product.|
|Legal aspects||No legal aspects|
|Environmental aspects|| Directive 2004/12/EC2
Although the individual components of laminates and metallized films are technically recyclable, the difficulty in sorting and separating the material precludes economically feasible recycling.
Facilities that might be interesting for you
|Institutes||UMII - IATE, UNINA - DSA, CSIRO, IIT|
|Companies||Sealed Air Corp., Amcor Flexibles, Tefeng plastic, EVAL Europe|
|References||  Koutchma Tatiana; Song Yoonseok; Setikaite Ilona; et al. (2010): PACKAGING EVALUATION FOR HIGH-PRESSURE HIGH-TEMPERATURE STERILIZATION OF SHELF-STABLE FOODS, JOURNAL OF FOOD PROCESS ENGINEERING, 33 (6): 1097-1114
 Koutchma, T. and Marcotte, M. (2009): High hydrostatic pressure processing of foods: challenges for pasteurization and sterilization. 8th World Congress of Chemical Engineering, Montreal, Canada, 23–27 August.
 Bull M. K.; Steele R. J.; Kelly M.; et al. (2010): Packaging under pressure: Effects of high pressure, high temperature processing on the barrier properties of commonly available packaging materials, INNOVATIVE FOOD SCIENCE & EMERGING TECHNOLOGIES , 11 (4): 533-537
 Huseyin Ayvaz (2010): Influence of Packaging Material and Storage Conditions on the Quality Attributes of Pressure-Assisted Thermally Processed Carrots, Electronic Thesis or Dissertation , Ohio State University  Fairclough J. P.A., Conti M. (2009): Influence of ultra-high pressure sterilization on the structure of polymer films, Packaging Technology and Science, 22 (5): 303–310
 Hartmann, C., and Delgado, A. (2003): The Influence of Transport Phenomena During High-Pressure Processing of Packed Food on The Uniformity of Enzyme Inactivation, Biotechnol. Bioeng. 82(6):725–735.
 Barbosa-Cánovas, G.V. and P. Juliano. (2008): Food Sterilization by combining High Pressure and Thermal Energy. In: Food Engineering: Integrated Approaches, G.F. Gutiérrez-López, G.V. Barbosa-Cánovas, J. Welti-Chanes, E. Parada Arias, pp. 9-46.
 Mauricio-Iglesias M, Jansana S, Peyron S, Gontard N, Guillard V.(2010): Effect of high-pressure/temperature (HP/T) treatments of in-package food on additive migration from conventional and bio-sourced materials, Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 27(1):118-27.
 Mauricio-Iglesias M., Peyron S., Chalier P., Gontard N. (2011): Scalping of four aroma compounds by one common (LDPE) and one biosourced (PLA
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The thickness of the material, as well as its thermal diffusivity, can affect the rate of heat conduction to (or from) the product during preheating (or cooling).warning.png"thermal diffusivity, thickness, seal strength, overall integrity, oxygen permeability and water vapour, max. temperature, light permeability for light sensitive products
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