Agriculture Reference
In-Depth Information
Different materials are used for food packaging applications like plastic, paper
and paperboard, metal, glass, or a combination of those materials, with different
physical and chemical characteristics depending on the type of food. Lately, there
s
been a lot of effort in the development of new packaging materials that are able to
keep the food quality, increase the shelf life, and at the same time have good
mechanical properties and are easy to process.
One way to improve the packaging is by the addition of nanoparticles to improve
characteristics such as the barrier properties to different gases, antimicrobial prop-
erties, and biodegradability, to incorporate sensors that can inform of the quality of
the food, etc. Currently, the largest category of nanotechnology applications for the
food sector is in food packaging materials: the global food and beverage packaging
market with nanomaterials was US
'
4.13 billion in 2008 and has been predicted to
$
grow to US
7.3 billion by 2014 (IR&P Inc. 2009 ), which represents an annual
growth rate of 11.65 %.
$
7.2.1 Packaging Materials with Improved Barrier Properties
A critical issue for a food packaging material is permeability (Robertson 2012 ): no
material is completely impermeable to water vapor, atmospheric gases, or different
natural substances that can be contained within the food or in the packaging
material itself. Also, different foods need different permeabilities through the
packaging material; thus, fresh fruits and vegetables need a continual supply of
oxygen for sustained cellular respiration and to avoid the spread of anaerobic
bacteria. Plastic containers for carbonated beverages, on the other hand, must
have high carbon dioxide and oxygen barriers to avoid decarbonation and oxidation
of the beverage. For other products the issue is water vapor permeability. As we
have seen, food products require sophisticated and different packaging functions. In
addition, as the distance between producers and consumers is getting longer with
the global market, the demands on the packaging industry are likely to rise.
Among the different materials used for food packaging, organic polymeric
materials [polypropylene (PP), polyethylene (PE), polyethylene terephthalate
(PET), polystyrene (PS), and polyvinyl chloride (PVC)] due to their low cost,
ease of processing, light weight, and formability are attractive alternatives for the
food packaging industry. The major problem is their inherent permeability to gases
and other small molecules. It depends on their polarity and the position of the
polymeric side chains, hydrogen bonding, molecular weight, cross-linking, crystal-
linity, and synthesis and processing methodology. No pure polymer possesses all
the barrier and mechanical properties needed for every food packaging application,
so usually polymer blends or complex multilayer films are used.
The option of using polymer nanocomposites as materials for food packaging is
the last one proposed for solving the mentioned problems. They are created by
dispersing inert nanoscale fillers throughout the polymeric matrix. Many different
nanomaterials are used as fillers like silica nanoparticles (Ke et al. 2010 ; Bracho
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