Environmental Engineering Reference
In-Depth Information
h e use of biopolymers by the food industry has faced feasibility prob-
lems related mainly to their relatively high cost and poor overall perfor-
mance when compared to those of synthetic polymers [11]. However, since
industries are concerned with sustainable development, the production
cost of biopolymers has decreased, allowing biopolymer-based materials
to be increasingly developed. More importantly, nanocomposites promise
to expand the use of edible and biodegradable ilms, since the addition of
nanoreinforcements has been related to improvements in overall perfor-
mance of biopolymers, enhancing their mechanical, thermal and barrier
properties, usually even at very low contents. h us, nanoparticles have an
important role in improving feasibility of the use of biopolymers for sev-
eral applications, including food packaging [12].
However, there are many safety concerns about nanomaterials, as their
size may allow them to penetrate into cells and eventually remain in the
system. h ere is no consensus about categorizing nanomaterials as new
materials. On one hand, the properties and safety of the materials in its
bulk form are usually well known, but the nanosized counterparts fre-
quently exhibit dif erent properties from those found at the macroscale.
h ere is limited scientiic data about migration of most types of nanopar-
ticles (NPs) from the packaging material into food, as well as their eventual
toxicological ef ects. It is reasonable to assume that migration may occur,
hence the need for accurate information on the ef ects of NPs to human
health following chronic exposure is imperative [13].
13.4.2 AntimicrobialSystems
Antimicrobial food packaging systems have received considerable atten-
tion since they help control the growth of pathogenic and spoilage micro-
organisms on food surfaces, where microbial growth predominates.
Antimicrobial nanocomposite systems are particularly interesting, since
materials in the nanoscale range have a higher surface-to-volume ratio
when compared with their microscale counterparts. Nanomaterials are
thus more ei cient, since they are able to attach more copies of microbial
molecules and cells. Nanoscale materials have been investigated for anti-
microbial activity as growth inhibitors or killing agents [14].
Silver is well known for its strong toxicity to a wide range of microorgan-
isms, besides some processing advantages such as high temperature stabil-
ity and low volatility. Silver nanoparticles have been shown to be ef ective
antimicrobials, even more ef ective than larger silver particles, thanks to
their larger surface area available for interaction with microbial cells. In
fact, the most common nanocomposites used as antimicrobial i lms for
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