98
glycol and other polyols, oligosaccharides, fatty acids and lipids are used as plasticizers for the formation of TPS (Bertolini 2010; Campos et al. 2011; Puthussery
et al. 2015; Jawaid and Swain 2017). Plasticizers improve the oxygen permeability
of extruded TPS. However, it may become susceptible to moisture, which accelerates the biodegradation of films (Siracusa et al. 2008). In addition, the incorporation
of nano fillers such as phyllosilicates, cellulose/Cs based NPs, carbon nanotubes,
metal oxides and other materials may improve the mechanical strength, water and
gas barrier properties of starch based films (Xie et al. 2013; López et al. 2015;
Gutiérrez and Alvarez 2017a). Native and thermoplastic starch is generally used in
biodegradable packaging formulations due to its low cost, abundant sources and
safe functions for the environment (Thiré 2010; Lagarón 2011).
Since the starch is cheap, renewable and has widely available sources, researchers are focused on functional properties of starches from different origins such as
ahipa, cassava (called also tapioca), corn, elephant foot yam, palm, potato, sugar
sago and wheat (Gutiérrez et al. 2015a,b,c,d). The mechanical properties of the
matrix may change depending on the origin of starch (Medeiros et al. 2010; Jiménez
et al. 2012).
Cellulose is composed of linear β-1,4 linked D-glucopyranose units, which is the
main component of plant cell wall materials (Khan et al. 2014; Bracone et al. 2016).
In addition to its extraction from plant sources such as woods, cotton, hemp, agricultural waste, aquatic plants and grasses, cellulose is also produced by
Gluconacetobacter species in form of bacterial nanocellulose (Abdul Khalil et al.
2012; Khan et al. 2014; Azeredo et al. 2017). The purity, high mechanical strength,
hydrophobicity and better gas barrier properties make bacterial cellulose more
advantageous than plant-based alternatives (Khan et al. 2014; Cazón et al. 2017).
However, the moisture sensitivity of bacterial nanocellulose impairs its oxygen barrier properties, especially at high relative moisture (Nair et al. 2014). After starch,
cellulose is the second most abundant, cheap and renewable source for food packaging applications (Vilarinho et al. 2018). Nanostructures from cellulose such as cellulose nanofibrils, nanocrystals and nanowhiskers can participate as fillers of
composite films due to their supreme mechanical and barrier properties due to their
good dispersion into the polymer matrix (Khan et al. 2014). In addition to cellulose,
hydroxypropyl methylcellulose and methylcellulose form transparent and flexible
films with a good gas and lipid barrier structure (Cazón et al. 2017).
Cs is a linear polysaccharide consisting of 1,4-linked 2-amino-2-deoxy-β-Dglucan, and the amino group can form interactions with anionic groups in an acidic
environment (Xu et al. 2005). It is the deacylated derivative of chitin in alkaline
medium (Kumar 2000; Elsabee and Abdou 2013). The biodegradable, non-toxic,
biocompatible, antimicrobial and good film-forming nature of Cs makes it favorable
for food packaging applications (Campos et al. 2011; Cazón et al. 2017; Merino
et al. 2018b, 2019b). Cs has selective gas permeability and mechanical properties in
addition to having a wide range of antimicrobial activity against bacteria, yeast and
molds (Elsabee and Abdou, 2013; Cazón et al. 2017).
Cs is not thermally stable, therefore the processes that require heat applications
such as extrusion, molding or heat sealing are not favorable for the production of
H. Cakmak and E. Sogut
glycol and other polyols, oligosaccharides, fatty acids and lipids are used as plasticizers for the formation of TPS (Bertolini 2010; Campos et al. 2011; Puthussery
et al. 2015; Jawaid and Swain 2017). Plasticizers improve the oxygen permeability
of extruded TPS. However, it may become susceptible to moisture, which accelerates the biodegradation of films (Siracusa et al. 2008). In addition, the incorporation
of nano fillers such as phyllosilicates, cellulose/Cs based NPs, carbon nanotubes,
metal oxides and other materials may improve the mechanical strength, water and
gas barrier properties of starch based films (Xie et al. 2013; López et al. 2015;
Gutiérrez and Alvarez 2017a). Native and thermoplastic starch is generally used in
biodegradable packaging formulations due to its low cost, abundant sources and
safe functions for the environment (Thiré 2010; Lagarón 2011).
Since the starch is cheap, renewable and has widely available sources, researchers are focused on functional properties of starches from different origins such as
ahipa, cassava (called also tapioca), corn, elephant foot yam, palm, potato, sugar
sago and wheat (Gutiérrez et al. 2015a,b,c,d). The mechanical properties of the
matrix may change depending on the origin of starch (Medeiros et al. 2010; Jiménez
et al. 2012).
Cellulose is composed of linear β-1,4 linked D-glucopyranose units, which is the
main component of plant cell wall materials (Khan et al. 2014; Bracone et al. 2016).
In addition to its extraction from plant sources such as woods, cotton, hemp, agricultural waste, aquatic plants and grasses, cellulose is also produced by
Gluconacetobacter species in form of bacterial nanocellulose (Abdul Khalil et al.
2012; Khan et al. 2014; Azeredo et al. 2017). The purity, high mechanical strength,
hydrophobicity and better gas barrier properties make bacterial cellulose more
advantageous than plant-based alternatives (Khan et al. 2014; Cazón et al. 2017).
However, the moisture sensitivity of bacterial nanocellulose impairs its oxygen barrier properties, especially at high relative moisture (Nair et al. 2014). After starch,
cellulose is the second most abundant, cheap and renewable source for food packaging applications (Vilarinho et al. 2018). Nanostructures from cellulose such as cellulose nanofibrils, nanocrystals and nanowhiskers can participate as fillers of
composite films due to their supreme mechanical and barrier properties due to their
good dispersion into the polymer matrix (Khan et al. 2014). In addition to cellulose,
hydroxypropyl methylcellulose and methylcellulose form transparent and flexible
films with a good gas and lipid barrier structure (Cazón et al. 2017).
Cs is a linear polysaccharide consisting of 1,4-linked 2-amino-2-deoxy-β-Dglucan, and the amino group can form interactions with anionic groups in an acidic
environment (Xu et al. 2005). It is the deacylated derivative of chitin in alkaline
medium (Kumar 2000; Elsabee and Abdou 2013). The biodegradable, non-toxic,
biocompatible, antimicrobial and good film-forming nature of Cs makes it favorable
for food packaging applications (Campos et al. 2011; Cazón et al. 2017; Merino
et al. 2018b, 2019b). Cs has selective gas permeability and mechanical properties in
addition to having a wide range of antimicrobial activity against bacteria, yeast and
molds (Elsabee and Abdou, 2013; Cazón et al. 2017).
Cs is not thermally stable, therefore the processes that require heat applications
such as extrusion, molding or heat sealing are not favorable for the production of
H. Cakmak and E. Sogut