Bio-nanocomposite materials with added functional properties have potential for the development of technologies such as active and intelligent packaging, high barrier packaging, nanosensors, freshness indicator, self-cleaning, and nanocoating.
However, the present level of improvements is not enough to compete with petroleum-based plastics, the authors noted in the Progress in Polymer Science journal.
“In particular, water resistance is too poor to utilize the bio-nanocomposites as packaging materials, especially in wet environmental conditions.
“Therefore, further improvement of the bio-nanocomposites is needed including development of the optimum formulation for the individual polymer and processing method to obtain desired properties to meet a wide range of applications as well as cost reduction of the bio-nanocomposites.”
Bio-nanocomposites consist of a biopolymer matrix reinforced with particles (nanoparticles) having at least one dimension in the nanometer range (1–100 nm).
The most studied suitable for packaging applications are starch and cellulose derivatives, polylactic acid (PLA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and polyhydroxybutyrate (PHB).
The most promising nanoscale fillers are layered silicate nanoclays such as montmorillonite and kaolinite.
What can they offer?
In food packaging, a major emphasis is on the development of high barrier properties against the diffusion of oxygen, carbon dioxide, flavour compounds, and water vapour, said the researchers.
The use of nanocomposite formulations is expected to considerably enhance the shelf-life of many types of food.
“Specific examples include packaging for processed meats, cheese, confectionery, cereals and boil-in-bag foods, also extrusion-coating applications in association with paperboard for fruit juice and dairy products, together with co-extrusion processes for the manufacture of beer and carbonated drinks bottles,” detailed the paper.
Biobased concerns
Several concerns must also be addressed prior to commercial use of biobased primary packaging materials.
These concerns include degradation rates under various conditions, changes in mechanical properties during storage, potential for microbial growth, and release of harmful compounds into packaged food products.
Biodegradability of the bio-nanocomposites can be fine tuned through proper choice of polymer matrix and nanoparticles.
However, biopolymers present relatively poor mechanical and barrier properties, which currently limit their industrial use, said Rhim et al.
Migration knowledge
When nanocomposites are applied into the food packaging materials, direct contact with food is only possible following migration of the nanoparticles.
Though there is limited scientific data about migration of nanoparticles from packaging materials into food, it is reasonable to assume that migration may occur because of their tiny dimensions.
The researchers said there is a crucial need to understand how nanoparticles act when they get into the body, how and if the nanoparticles are absorbed by the different organs, how the body metabolizes them and how and in which way the body eliminate them.
Source: Progress in Polymer Science
DOI: 10.1016/j.progpolymsci.2013.05.008
“Bio-nanocomposites for food packaging applications”
Authors: Jong-Whan Rhim, Hwan-Man Park, Chang-Sik Ha