Agriculture Reference
In-Depth Information
used was more hydrophilic, the degradation was more pronounced. Fukushima
et al. (
2009
) concluded that the higher biodegradability rates of the nanocomposites
were due to the high relative hydrophilicity of the clays. This hydrophilicity
allowed an easier permeability of water into the polymer matrix, thus activating
the hydrolytic degradation process.
Also, a higher biodegradability rates have been observed for other
bio-nanocomposite films compared to their biopolymer counterparts as for PHB
(Maiti et al.
2007
), soy protein-based nanocomposite (Sasmal et al.
2009
), or nano-
silica/starch/polyvinyl alcohol films (Tang et al.
2008a
).
Other studies, however, present results that indicate a lower degradability rate
for the nanocomposites, like for PBS/organoclay nanocomposite films after a soil
compost test (Lee et al.
2002
), PHB nanocomposite (Wu and Wu
2006
), or
PLA/chitosan/organically modified nanoclay (Sinha Ray et al.
2003b
). They indi-
cated that the lower degradability rate was due to the higher barrier properties of the
nanocomposites. Other authors (Rhim et al.
2006
; Someya et al.
2007
; Song
et al.
2009
) suggest that the reduced biodegradability of nanocomposites of PBS
and PHB is due not to the barrier properties but to the strong antimicrobial activity
of the organoclay against food poisoning bacteria (especially Gram positive) and
proposed that the antimicrobial action was due to the quaternary ammonium group
in the modified organoclay. In this manner, the degradation of the polymer due to
this type of bacteria was retarded, and the biodegradability rate was lower. They
also suggested that the biodegradability rate could be controlled by modifying the
amount of solvents used or by the incorporation of different types of organoclays
modified with different types of surfactants.
According to the different research studies, nanoparticles can have two opposite
effects on polymer nanocomposites: either degradation or stabilization depending
on processing and environmental conditions (Kumar et al.
2009
). Packaging indus-
try can take advantage of this fact depending on the final use of the product.
7.3 Safety Concerns and Current Regulation
As we have seen, nanomaterials can serve for many new applications in the food
industry, from stronger flavorings and colorings, and nutritional additives to
enhanced materials with antibacterial or better barrier properties for food packag-
ing. However, as nanomaterials have different properties compared to the bulk
material, scientific concerns have been raised about the possible hazards to human
health and the environment. The potential risks introduced by the use of
nanomaterials for food packaging applications should be explored by the industry
as a part of the development process.
Currently, there is a lack of regulation concerning nanomaterials in most of the
countries. While this emerging technology is still in the research stage and benefits
and risks are being discovered, there are already commercialized products with
nanoparticles available in the market, generally with little or no information to the
