Application of Microbial-Synthesized Nanoparticles …
409
3.1.4 Food Preservatives
The utilization of some traditional food preservatives for long durations may result in
headache, gradual loss of mental concentration, and low immune response (Kumar
et al. 2019). Some nanoparticles can be used for the production of nano-preservatives,
as an alternative strategy to inhibit or reduce the microbial growth control, as this
increases the products shelf life (He and Hwang 2016). Several biosynthetic nanopreservatives have been produced and tested for the control of bacteria and fungi,
using metals such as silver and gold, as well as some metal oxides like Fe 3 O 4 , MgO,
and TiO 2 .
The employment of biocompatible AgNPs for the control of gram-negative and
gram-positive bacteria, like Escherichia coli and Staphylococcus aureus was elaborated by García-Ruiz et al. (2015), presenting a growth-inhibitory effect of two
nanoparticles (PEG-Ag NPs and GSH-Ag NPs) on wine. The utilization of Candida
lusitaniae in the production of AgNPs for the bacterial control of gram-negative
Klebsiella pneumoniae and gram-positive Staphylococcus aureus was elaborated by
Eugenio et al. (2016).
The utilization of supernatant media from cellular biomass culture for the preparation of nano-preservatives has been described in the literature, as some yeasts
present the nitrate reductase activity. For example, Fernández et al. (2016) evaluated the antifungal activity of AgNPs produced from supernatant culture media
of Cryptococcus laurentii and Rhodotorula glutinis against the phytopathogenic
fungus Botrytis cinerea, Penicillium expansum, Aspergillus niger, Alternaria sp.,
and Rhizopus sp.
The utilization of metal oxides like MgO was studied by Das et al. (2018), where
leaf extracts of Bauhinia purpurea were used for the production of nanoflakes with
antibacterial activity on Staphylococcus aureus. The elaboration of supermagnetic
Fe 3 O 4 -MgO nanoparticles using the essential oil from nutmeg has been proven to
present antibacterial and antifungal activities (Mousavi et al. 2019). The reactive
oxygen species (ROS) in TiO 2 photocatalysis (TPC) is capable of causing the inactivation of microorganisms, by damaging irreversibly the cell wall and bacterial
membrane, causing ions and small molecules leakage, degradation of cells component and finally death (Zhu et al. 2018). TiO 2 is usually used in sweets and presents
great potential of application in bottles, milk boxes, and packing foils (Ghosh and
Das 2015). TiO 2 can be also applied in drinking water (Donovan et al. 2016), fresh
vegetables (Pignata et al. 2017), and drinks (Chai et al. 2014).
3.1.5 Nanocapsules
The nanoencapsulation is defined as the technology of packaging nanoparticles of
solid, liquid, or gas (core or active), within a secondary material (matrix or shell),
to form the nanocapsules (Augustin and Hemar 2009). Nanocapsules are structures
that vary from 0.1 nm to 1 µm size, and due to its increased range of applications,
this core may contain active ingredients, which may have several benefits, such as
409
3.1.4 Food Preservatives
The utilization of some traditional food preservatives for long durations may result in
headache, gradual loss of mental concentration, and low immune response (Kumar
et al. 2019). Some nanoparticles can be used for the production of nano-preservatives,
as an alternative strategy to inhibit or reduce the microbial growth control, as this
increases the products shelf life (He and Hwang 2016). Several biosynthetic nanopreservatives have been produced and tested for the control of bacteria and fungi,
using metals such as silver and gold, as well as some metal oxides like Fe 3 O 4 , MgO,
and TiO 2 .
The employment of biocompatible AgNPs for the control of gram-negative and
gram-positive bacteria, like Escherichia coli and Staphylococcus aureus was elaborated by García-Ruiz et al. (2015), presenting a growth-inhibitory effect of two
nanoparticles (PEG-Ag NPs and GSH-Ag NPs) on wine. The utilization of Candida
lusitaniae in the production of AgNPs for the bacterial control of gram-negative
Klebsiella pneumoniae and gram-positive Staphylococcus aureus was elaborated by
Eugenio et al. (2016).
The utilization of supernatant media from cellular biomass culture for the preparation of nano-preservatives has been described in the literature, as some yeasts
present the nitrate reductase activity. For example, Fernández et al. (2016) evaluated the antifungal activity of AgNPs produced from supernatant culture media
of Cryptococcus laurentii and Rhodotorula glutinis against the phytopathogenic
fungus Botrytis cinerea, Penicillium expansum, Aspergillus niger, Alternaria sp.,
and Rhizopus sp.
The utilization of metal oxides like MgO was studied by Das et al. (2018), where
leaf extracts of Bauhinia purpurea were used for the production of nanoflakes with
antibacterial activity on Staphylococcus aureus. The elaboration of supermagnetic
Fe 3 O 4 -MgO nanoparticles using the essential oil from nutmeg has been proven to
present antibacterial and antifungal activities (Mousavi et al. 2019). The reactive
oxygen species (ROS) in TiO 2 photocatalysis (TPC) is capable of causing the inactivation of microorganisms, by damaging irreversibly the cell wall and bacterial
membrane, causing ions and small molecules leakage, degradation of cells component and finally death (Zhu et al. 2018). TiO 2 is usually used in sweets and presents
great potential of application in bottles, milk boxes, and packing foils (Ghosh and
Das 2015). TiO 2 can be also applied in drinking water (Donovan et al. 2016), fresh
vegetables (Pignata et al. 2017), and drinks (Chai et al. 2014).
3.1.5 Nanocapsules
The nanoencapsulation is defined as the technology of packaging nanoparticles of
solid, liquid, or gas (core or active), within a secondary material (matrix or shell),
to form the nanocapsules (Augustin and Hemar 2009). Nanocapsules are structures
that vary from 0.1 nm to 1 µm size, and due to its increased range of applications,
this core may contain active ingredients, which may have several benefits, such as