(1) connection of negative charge microbiological cellule
pellicles with amine species and positively charged with
chitosan that alters the barrier properties and leads to intracellular content leakage and cell death (Pan et al. 2015);
(2) the second method is based on the chelating features of
chitosan, and (3) the molecular mass of chitosan may too
affect its anti-microbiological actions (Verlee et al. 2017).
Chitosan selectively connects to metals, limiting several
metabolic enzymes in microbial cells, blockading acting
centers, and decreasing its development. Therefore, the
antimicrobial function of chitosan is primarily caused by its
molecular mass, deacetylation degree, and other physicochemical properties (Kumar et al. 2019).
Nevertheless, in particular for food conservation and
packing applications, additional improvements in the
antimicrobial characteristics of chitosan are advantageous, to
improve its antimicrobial features, natural antimicrobials,
and their nanostructures (e.g., metal nanoparticles and metal
oxides) were used Matharu et al. (2018).
3.4 Measuring Thermal Properties Using
Thermogravimetric Analysis
and Differential Scanning Calorimetry
Thermal stability is a determining factor in the functional
properties of biofilms produced from food waste. This is
because the application heat on different surfaces can change
the biofilm structural parameters, which influence the functionality and stability of the bioplastics (Muralidharan et al.
2020).
In a study on the thermal characterization of corn starch
bioplastics, containing sprout flour byproducts conducted by
Silva et al. (2020), these noticed that the different components
and concentrations found in biofilms presented various capabilities during heating. For all the manufactured films, three
mass loss peaks were evidenced, with two endothermic peaks
(heat absorption): one in the glass transition region and the
other in the fusion region, and an exothermic peak (heat
release), which can be explained by the plurality of ingredients
and complex reactions that occur at high temperatures (Silva
et al. 2020). The glass transition and melting temperatures of
different materials are relevant for estimating the barrier
properties of oxygen and water vapor, measuring the storage
and transport conditions, using them in the industrial processes
(Oluwasina et al. 2019). Therefore, the manufactured bioplastics can also be used in foods that do not undergo thermal
processing at high temperatures, because there is a low transition temperature that can modify the components (Santana
et al. 2018). According to Yamada et al. (2020), the insights
recommended that the soybean protein is thermally stabilized
by the effect with the 1% formaldehyde aqueous solution–
methanol (HCHO), and the bioplastic produced demonstrated
a thermal stability below 200 °C, due to the configuration of a
3D (three-dimensional) association with methylene containing
cross-linkages with peptide chains. The authors concluded that
soy proteins with HCHO reactions may make a significant
function in the application of biodegradable resources, e.g.,
throw away objects, industrialized pieces, and unconventional
plastic substances.
In a study developed by Dehghan et al. (2019), the
addition of bamboo flour to the high-density polylactic acid
(PLA) composites resulted in an efficient raise in the glass
transition temperature of the composites. A slight increase in
the transition temperature compared to that of the pure
polymer represents a change in the softness and flexibility of
the bioplastics (Yamada et al. 2020). It was also observed
that the crystallinity degree of the composites increased
compared to that of the pure polymer, which is possibly due
to the presence of coupling agents in the composite structure
(Velasco et al. 1996). This coupling agent is the result of an
increase in the crystalline core, which directly leads to an
increase in the crystal development around the fibers and an
increase in the polymer crystallinity degree (Velasco et al.
1996). These factors significantly improve the connection
between polymer chains and biopolymer fibers.
4 Applications of Bioplastics Produced
by Food Waste
Plastic composes a variety of products in various fields due
to its properties as a polymeric material. Plastics have
become a worldwide concern due to their increasing levels
of production and use. Food waste represents great losses of
various resources such as land, labor, and water. The Food
and Agriculture Organization (FAO) (2018) defines food
waste as quality and quantity losses resulting from consumer
behavior and retailer marketing (Bilo et al. 2018).
The production of synthetic plastics from irreversible
processes is a large environmental problem. Therefore, due
to their similar functions, bioplastics are a sustainable
alternative to the concern to environmental contamination by
synthetic materials of low degradability (Tsang et al. 2019).
4.1 Rice Straw Bioplastics Applied in Packaging
Cellulose is the most appreciated biopolymer, and it is present in wood, cotton, and rice straw (Spadetti et al. 2017). It
consists of glucose units bound by a glycosidic bond. Cellulose fibers have several advantages, e.g., low cost, availability, renewability, low density, low thermal expansion,
and water insolubility. Moreover, cellulose nanofibers
obtained from horticulture have been studied because of
their abundance and annual sustainability (Riva et al. 2018).
Bioconversion of Food Waste into Bioplastics
289
pellicles with amine species and positively charged with
chitosan that alters the barrier properties and leads to intracellular content leakage and cell death (Pan et al. 2015);
(2) the second method is based on the chelating features of
chitosan, and (3) the molecular mass of chitosan may too
affect its anti-microbiological actions (Verlee et al. 2017).
Chitosan selectively connects to metals, limiting several
metabolic enzymes in microbial cells, blockading acting
centers, and decreasing its development. Therefore, the
antimicrobial function of chitosan is primarily caused by its
molecular mass, deacetylation degree, and other physicochemical properties (Kumar et al. 2019).
Nevertheless, in particular for food conservation and
packing applications, additional improvements in the
antimicrobial characteristics of chitosan are advantageous, to
improve its antimicrobial features, natural antimicrobials,
and their nanostructures (e.g., metal nanoparticles and metal
oxides) were used Matharu et al. (2018).
3.4 Measuring Thermal Properties Using
Thermogravimetric Analysis
and Differential Scanning Calorimetry
Thermal stability is a determining factor in the functional
properties of biofilms produced from food waste. This is
because the application heat on different surfaces can change
the biofilm structural parameters, which influence the functionality and stability of the bioplastics (Muralidharan et al.
2020).
In a study on the thermal characterization of corn starch
bioplastics, containing sprout flour byproducts conducted by
Silva et al. (2020), these noticed that the different components
and concentrations found in biofilms presented various capabilities during heating. For all the manufactured films, three
mass loss peaks were evidenced, with two endothermic peaks
(heat absorption): one in the glass transition region and the
other in the fusion region, and an exothermic peak (heat
release), which can be explained by the plurality of ingredients
and complex reactions that occur at high temperatures (Silva
et al. 2020). The glass transition and melting temperatures of
different materials are relevant for estimating the barrier
properties of oxygen and water vapor, measuring the storage
and transport conditions, using them in the industrial processes
(Oluwasina et al. 2019). Therefore, the manufactured bioplastics can also be used in foods that do not undergo thermal
processing at high temperatures, because there is a low transition temperature that can modify the components (Santana
et al. 2018). According to Yamada et al. (2020), the insights
recommended that the soybean protein is thermally stabilized
by the effect with the 1% formaldehyde aqueous solution–
methanol (HCHO), and the bioplastic produced demonstrated
a thermal stability below 200 °C, due to the configuration of a
3D (three-dimensional) association with methylene containing
cross-linkages with peptide chains. The authors concluded that
soy proteins with HCHO reactions may make a significant
function in the application of biodegradable resources, e.g.,
throw away objects, industrialized pieces, and unconventional
plastic substances.
In a study developed by Dehghan et al. (2019), the
addition of bamboo flour to the high-density polylactic acid
(PLA) composites resulted in an efficient raise in the glass
transition temperature of the composites. A slight increase in
the transition temperature compared to that of the pure
polymer represents a change in the softness and flexibility of
the bioplastics (Yamada et al. 2020). It was also observed
that the crystallinity degree of the composites increased
compared to that of the pure polymer, which is possibly due
to the presence of coupling agents in the composite structure
(Velasco et al. 1996). This coupling agent is the result of an
increase in the crystalline core, which directly leads to an
increase in the crystal development around the fibers and an
increase in the polymer crystallinity degree (Velasco et al.
1996). These factors significantly improve the connection
between polymer chains and biopolymer fibers.
4 Applications of Bioplastics Produced
by Food Waste
Plastic composes a variety of products in various fields due
to its properties as a polymeric material. Plastics have
become a worldwide concern due to their increasing levels
of production and use. Food waste represents great losses of
various resources such as land, labor, and water. The Food
and Agriculture Organization (FAO) (2018) defines food
waste as quality and quantity losses resulting from consumer
behavior and retailer marketing (Bilo et al. 2018).
The production of synthetic plastics from irreversible
processes is a large environmental problem. Therefore, due
to their similar functions, bioplastics are a sustainable
alternative to the concern to environmental contamination by
synthetic materials of low degradability (Tsang et al. 2019).
4.1 Rice Straw Bioplastics Applied in Packaging
Cellulose is the most appreciated biopolymer, and it is present in wood, cotton, and rice straw (Spadetti et al. 2017). It
consists of glucose units bound by a glycosidic bond. Cellulose fibers have several advantages, e.g., low cost, availability, renewability, low density, low thermal expansion,
and water insolubility. Moreover, cellulose nanofibers
obtained from horticulture have been studied because of
their abundance and annual sustainability (Riva et al. 2018).
Bioconversion of Food Waste into Bioplastics
289