Agriculture Reference
In-Depth Information
be used to coat very hydrophilic food systems such as precut vegetables and fruits
adding antimicrobial agents or more vitamins (Vargas et al.
2008
).
Nowadays, edible nanolaminates are fabricated from lipids, polysaccharides,
and proteins. They are poor at protecting against moisture, although polysaccharide
and protein-based films are good barriers against carbon dioxide and oxygen. On
the other hand, lipid-based nanolaminates, although good at protecting food from
moisture, have poor barrier to other gases and limited mechanical strength.
Research is being done in identifying additives as polyols to improve them because
neither lipids nor polysaccharides nor proteins deliver all of the desired properties
in an edible coating. At present, coating foods that include nanolaminates involves
either dipping the food into different solutions containing target substances or
spraying the substance onto the food surface. Frequently, the formation of the
nanolaminate is a result of the electrostatic attraction between compounds with
opposite charges, and there are also various methods, which could cause adsorption.
As a result, different nanolaminates might include various functional agents as
antioxidants, antimicrobials, enzymes, anti-browning, colors, and flavors.
The second approach is the use of edible films with nanosized fillers. In this case,
clay nanoparticles are the most important group of nanoparticles used to enhance
the properties of edible films. The physical and mechanical properties of the pure
polymer or conventional composites can be improved in a large scale when using a
nanometer-sized dispersion of clay to create a polymer-clay nanocomposite (Rhim
and Ng
2007
). Nanoclay particles have been combined with both proteins
(Shotornvit et al.
2009
) and polysaccharides (Casariego et al.
2009
; Tang
et al.
2008b
) to create enhanced edible films.
Also, films have been created by adding other nanoparticles, such as
tripolyphosphate-chitosan (De Moura et al.
2009
), microcrystalline cellulose
(Bilbao-S
ยด
inz et al.
2010
), or silicon dioxide (Tang et al.
2009
), to biopolymers.
Using these nanoparticles, the moisture barrier properties have been improved and
the microbial growth restricted. Rhim et al. (
2006
) studied different nanoparticles to
improve the physical properties of chitosan-based films that also showed antimi-
crobial activity in a certain extent. The optical properties are affected to a greater
or lesser extent depending on the type of nanoclay used; this has been observed
in isolated whey protein-based films (Shotornvit et al.
2009
) and gelatin-clay
nanocomposites (Farahnaky et al.
2014
) where light transmittance of the gelatin
decreased with the inclusion of the nanoclay. The incorporation of other
nanoparticles like porous silica-coated titania changed dramatically the appearance
of whey protein-isolated films from a transparent appearance to opaque (Kadam
et al.
2013
).
Recently, the addition of bacterial cellulose nanocrystals to create a gelatin
nanocomposite film (George and Siddaramaiah
2012
) reduced the moisture affinity
of gelatin, a very interesting property for edible packaging applications. The
dynamic mechanical properties and degradation temperature of gelatin were also
improved.
Other nanomaterials like carbon nanotubes have also been used as nanofillers in
gelatin films. As studied by Ortiz-Zarama et al. (
2014
), the mechanical properties of
