97
and the use of nanocomposites as carriers of active compounds such as antioxidants
and antimicrobials (Yildirim et al. 2018; Merino et al. 2018a, 2019a).
Biobased composite/nanocomposite films for food packaging applications made
from natural biomass (polysaccharides, proteins and lipids and waxes), and the
effects of functional nanomaterials incorporated into the composites are discussed
in this chapter.
6.2 Biobased Polymers
6.2.1 Polysaccharide Biomass
Biomass based on polysaccharides such as starch (native, thermoplastic etc.), cellulose and its derivatives (carboxymethyl cellulose, hydroxypropyl cellulose,
hydroxypropyl methylcellulose, methyl cellulose), alginate, chitin, chitosan (Cs),
maltodextrin, agar, pectin, carrageenan, heparin, chondroitin, glucomannan, pullulan, kefiran, curdlan and gums (gellan, guar, locust bean, mesquite, tara) can be used
as pure polymer, polymer matrix or filler (Miller and Krochta 1997; Tharanathan
2003; Lacroix and Le Tien 2005; Falguera et al. 2011; Bonilla et al. 2012; Cirillo
et al. 2015; Zia et al. 2015; Cazón et al. 2017; Gutiérrez 2017a; Araque et al. 2018).
The mostly studied polysaccharide biomasses and their properties are summarized below.
Starch is composed of two macromolecules: amylose and amylopectin. Amylose
is a linear polymer consists of D-glucose units linked with α-1-4 bonds, while amylopectin consist of both linear glucose segments with α-1-4 bond and α-1-6 linked
glucose segments at the branching points (Pérez et al. 2009; Bertolini 2010;
Gutiérrez et al. 2014). The crystalline structure of native starch is attributed to amylopectin, while the crystalline and amorphous lamellas of amylopectin are packed in
larger structures called block-lets (Bertolini 2010; Gutiérrez 2018e). However, the
amorphous structure is dominant in the starch granules, since the amylose and most
of the amylopectin are formed by an amorphous structure (Pérez et al. 2009).
Temperature, pressure and pH may limit the film forming capacity of native starches
regarding sensitivity to high shear, decomposition with temperature, retrogradation
and syneresis (Bertolini 2010; Jiménez et al. 2012; Gutiérrez and Álvarez 2016;
Gutiérrez and González 2016). Thus, the semi crystalline structure of starch is transformed into a homogeneous amorphous matrix to improve processing ability
(Bertolini 2010). Applications of mechanical or thermal energy are required together
with the presence of water for starch destructuring and, therefore, the production of
thermoplastic starch (TPS) (Bertolini 2010; Thiré 2010; Puthussery et al. 2015;
Gutiérrez et al. 2018a; Gutiérrez and Alvarez 2018). In addition to water, polyols
such as glycerol and sorbitol provide the plasticizing effect, and increase flexibility
and decrease the brittleness in films (Thiré 2010; Jiménez et al. 2012; Medina
Jaramillo et al. 2016). Water, glycerol, sorbitol, propylene glycol, polyethylene
6 Functional Biobased Composite Polymers for Food Packaging Applications
and the use of nanocomposites as carriers of active compounds such as antioxidants
and antimicrobials (Yildirim et al. 2018; Merino et al. 2018a, 2019a).
Biobased composite/nanocomposite films for food packaging applications made
from natural biomass (polysaccharides, proteins and lipids and waxes), and the
effects of functional nanomaterials incorporated into the composites are discussed
in this chapter.
6.2 Biobased Polymers
6.2.1 Polysaccharide Biomass
Biomass based on polysaccharides such as starch (native, thermoplastic etc.), cellulose and its derivatives (carboxymethyl cellulose, hydroxypropyl cellulose,
hydroxypropyl methylcellulose, methyl cellulose), alginate, chitin, chitosan (Cs),
maltodextrin, agar, pectin, carrageenan, heparin, chondroitin, glucomannan, pullulan, kefiran, curdlan and gums (gellan, guar, locust bean, mesquite, tara) can be used
as pure polymer, polymer matrix or filler (Miller and Krochta 1997; Tharanathan
2003; Lacroix and Le Tien 2005; Falguera et al. 2011; Bonilla et al. 2012; Cirillo
et al. 2015; Zia et al. 2015; Cazón et al. 2017; Gutiérrez 2017a; Araque et al. 2018).
The mostly studied polysaccharide biomasses and their properties are summarized below.
Starch is composed of two macromolecules: amylose and amylopectin. Amylose
is a linear polymer consists of D-glucose units linked with α-1-4 bonds, while amylopectin consist of both linear glucose segments with α-1-4 bond and α-1-6 linked
glucose segments at the branching points (Pérez et al. 2009; Bertolini 2010;
Gutiérrez et al. 2014). The crystalline structure of native starch is attributed to amylopectin, while the crystalline and amorphous lamellas of amylopectin are packed in
larger structures called block-lets (Bertolini 2010; Gutiérrez 2018e). However, the
amorphous structure is dominant in the starch granules, since the amylose and most
of the amylopectin are formed by an amorphous structure (Pérez et al. 2009).
Temperature, pressure and pH may limit the film forming capacity of native starches
regarding sensitivity to high shear, decomposition with temperature, retrogradation
and syneresis (Bertolini 2010; Jiménez et al. 2012; Gutiérrez and Álvarez 2016;
Gutiérrez and González 2016). Thus, the semi crystalline structure of starch is transformed into a homogeneous amorphous matrix to improve processing ability
(Bertolini 2010). Applications of mechanical or thermal energy are required together
with the presence of water for starch destructuring and, therefore, the production of
thermoplastic starch (TPS) (Bertolini 2010; Thiré 2010; Puthussery et al. 2015;
Gutiérrez et al. 2018a; Gutiérrez and Alvarez 2018). In addition to water, polyols
such as glycerol and sorbitol provide the plasticizing effect, and increase flexibility
and decrease the brittleness in films (Thiré 2010; Jiménez et al. 2012; Medina
Jaramillo et al. 2016). Water, glycerol, sorbitol, propylene glycol, polyethylene
6 Functional Biobased Composite Polymers for Food Packaging Applications