121
Mt has also limited antimicrobial activity. A bacteriostatic effect against Gram
positive bacteria from nanocomposite films based on gelatin, WPI and κ-carrageenan
containing Cloisite 30B (organically modified Mt) has been reported in the literature (Sothornvit et al. 2009; Kanmani and Rhim 2014; Rhim and Wang 2014).
Although no antibacterial effect was observed from the Cloisite-Na
+
and Cloisite
20A-reinforced WPI-based films. Similarly, Heydari et al. (2013) did not observe
antibacterial activity against Gram positive and Gram negative bacteria (E. coli and
S. aureus) for Na-Mt-containing corn starch-based films.
Metal and metal oxide NPs are generally used to function as antimicrobial and
UV-blocking agents. In particular, Ag NPs are combined with the clay NPs for their
supreme contribution to the mechanical, thermal, optical and antimicrobial improvement in the film structure. Kanmani and Rhim (2014) reported that Ag NPs in
gelatin- based films had promising results to inhibit Gram positive and negative
strains, however, the antibacterial effect was more pronounced for Mt and Ag
NP-reinforced films (Kanmani and Rhim 2014). De Moura et al. (2012) found that
the size of NPs can also promote the bactericidal effect, such as a smaller NP diameter (41 nm) in Ag NP-reinforced HPMC films had a better antibacterial effect
against E. coli and S. aureus strains compared to nanocomposites with bigger
(100 nm) Ag NPs (De Moura et al. 2012).
Although these films are produced for food packaging applications, only antimicrobial activity is determined by in vitro methods and only some of them are applied
in real food samples. Therefore, these studies lack of information about the compatibility of the nanocomposite films with food, the possible effects on food quality
during the shelf-life, production costs and the safety for human consumption.
Especially the migration of NPs from the nanocomposites into food matrices should
be quantified with appropriate methods in order to assess the risk exposure related
to the consumption of that particular food (Huang et al. 2015; Honarvar et al. 2016).
Regarding the plastics, the European Commission has established an overall migration limit of 60 mg of material/kg of food matrix (or simulant) (Avella et al. 2005;
Huang et al. 2015). For those materials that migrate to food matrix and that exhibit
potential toxic and hazardous effects, a specific migration limit has been included
for each substance in the regulations of European Union (EU) No: 10/2011 entitled:
‘Plastic materials and articles intended to come into contact with food’. In this context, the migration of Fe, Mg and Si from nanocomposite packaging material containing Mt was tested by Avella et al. (2005) in both foods (lettuce and spinach) and
simulant food (water). The authors demonstrated that these composite packaging
films were below the overall migration limit of European legislation and had the
potential to be used as a food packaging material (Avella et al. 2005).
6.7 Conclusions and Remarks
This chapter presents the production methods, classifications and functional properties of biobased nanocomposites, focusing mainly on polysaccharide, protein and
lipid-based polymers containing nanocellulose and nanoclays as reinforcing agents.
6 Functional Biobased Composite Polymers for Food Packaging Applications
Mt has also limited antimicrobial activity. A bacteriostatic effect against Gram
positive bacteria from nanocomposite films based on gelatin, WPI and κ-carrageenan
containing Cloisite 30B (organically modified Mt) has been reported in the literature (Sothornvit et al. 2009; Kanmani and Rhim 2014; Rhim and Wang 2014).
Although no antibacterial effect was observed from the Cloisite-Na
+
and Cloisite
20A-reinforced WPI-based films. Similarly, Heydari et al. (2013) did not observe
antibacterial activity against Gram positive and Gram negative bacteria (E. coli and
S. aureus) for Na-Mt-containing corn starch-based films.
Metal and metal oxide NPs are generally used to function as antimicrobial and
UV-blocking agents. In particular, Ag NPs are combined with the clay NPs for their
supreme contribution to the mechanical, thermal, optical and antimicrobial improvement in the film structure. Kanmani and Rhim (2014) reported that Ag NPs in
gelatin- based films had promising results to inhibit Gram positive and negative
strains, however, the antibacterial effect was more pronounced for Mt and Ag
NP-reinforced films (Kanmani and Rhim 2014). De Moura et al. (2012) found that
the size of NPs can also promote the bactericidal effect, such as a smaller NP diameter (41 nm) in Ag NP-reinforced HPMC films had a better antibacterial effect
against E. coli and S. aureus strains compared to nanocomposites with bigger
(100 nm) Ag NPs (De Moura et al. 2012).
Although these films are produced for food packaging applications, only antimicrobial activity is determined by in vitro methods and only some of them are applied
in real food samples. Therefore, these studies lack of information about the compatibility of the nanocomposite films with food, the possible effects on food quality
during the shelf-life, production costs and the safety for human consumption.
Especially the migration of NPs from the nanocomposites into food matrices should
be quantified with appropriate methods in order to assess the risk exposure related
to the consumption of that particular food (Huang et al. 2015; Honarvar et al. 2016).
Regarding the plastics, the European Commission has established an overall migration limit of 60 mg of material/kg of food matrix (or simulant) (Avella et al. 2005;
Huang et al. 2015). For those materials that migrate to food matrix and that exhibit
potential toxic and hazardous effects, a specific migration limit has been included
for each substance in the regulations of European Union (EU) No: 10/2011 entitled:
‘Plastic materials and articles intended to come into contact with food’. In this context, the migration of Fe, Mg and Si from nanocomposite packaging material containing Mt was tested by Avella et al. (2005) in both foods (lettuce and spinach) and
simulant food (water). The authors demonstrated that these composite packaging
films were below the overall migration limit of European legislation and had the
potential to be used as a food packaging material (Avella et al. 2005).
6.7 Conclusions and Remarks
This chapter presents the production methods, classifications and functional properties of biobased nanocomposites, focusing mainly on polysaccharide, protein and
lipid-based polymers containing nanocellulose and nanoclays as reinforcing agents.
6 Functional Biobased Composite Polymers for Food Packaging Applications