17
applying a polymer coating allows to protect EOs due to its high volatility. The
encapsulated product improves the EO stability, which favors its controlled release,
thus they can be applied as an antimicrobial agent in AP. Although this methodology is gaining relevance, there are still few reported works with application in polyolefin films (Bile et al. 2016; Ribeiro-Santos et al. 2017; Zanetti et al. 2018).
Another approach to immobilize active agents in polymer matrix is through their
absorption or attachment in solid inert carriers. Also, the simultaneous incorporation of an active agent and an inert particle into a polymer matrix can improve the
antimicrobial efficiency by agent-controlled release. There are different alternatives
to incorporate or tailor the activity in packaging films by using carrier particles and
active agents. Recent reports on these methodologies applied to polyolefin matrices
have been analyzed in the following systems: cellulose/nisin (Lu et al. 2018), cellulose/titanium oxide (TiO 2 ) (Shah and Pandey 2017), starch/sorbitol (Pirooz et al.
2018), as well as wood flour and molecular sieves with biologically active substances of EOs (Urbankova et al. 2015).
2.5.2 Biocidal Activity by Incorporating Inorganic Particles
The use of inorganic particles as polyolefin reinforcements to develop composite
and nanocomposite materials is widely known. These fillers improve the mechanical performance of polymeric materials, as well as modify their permeability and,
depending on particle nature, may include functionalities or specific activity to the
polymer. In this sense, the particles can be ‘active’ themselves or act as a carrier/
support of active agents.
To prevent or reduce the growth of microorganisms in foods, antimicrobial packaging made from active films can be used. Many research papers related to this topic
have recently been published, which have focused on polyolefin-based nanocomposites and inorganic particles. In this regard, Ag NPs have been widely used due to
its high efficiency as a toxic agent for different microorganism strains. Its high antimicrobial effectivity can be associated with the large surface area of these particles,
which allows a close interaction with microorganism cells (Carbone et al. 2016).
The antibacterial activity is the result of various processes that can have an adverse
effect on protein synthesis and DNA, or involve cell damage (Cavaliere et al. 2015).
Ag NPs also have the ability to absorb and decompose ethylene, which has a positive impact on the food shelf-life, mainly on fresh vegetables and fruits (Bratovčić
et al. 2015). On the other hand, another advantage of Ag NPs is the good thermal
stability, which allows a wide range of polymer processing alternatives
(Beigmohammadi et al. 2016). Similarly, TiO 2 NPs are commonly used in different
fields because of its self-disinfecting property. TiO 2 induces the inactivation of
pathogenic bacteria, promoting phospholipid peroxidation of microbial cell membranes (Bodaghi et al. 2013). Meanwhile, copper (Cu) NPs have biocidal properties,
which present a wide range of action against bacteria and molds, adding a good
cost-effective relationship (Kalatehjari et al. 2015; Xiong et al. 2015). Although this
2 Active Packaging Films Based on Polyolefins Modified by Organic and Inorganic…
applying a polymer coating allows to protect EOs due to its high volatility. The
encapsulated product improves the EO stability, which favors its controlled release,
thus they can be applied as an antimicrobial agent in AP. Although this methodology is gaining relevance, there are still few reported works with application in polyolefin films (Bile et al. 2016; Ribeiro-Santos et al. 2017; Zanetti et al. 2018).
Another approach to immobilize active agents in polymer matrix is through their
absorption or attachment in solid inert carriers. Also, the simultaneous incorporation of an active agent and an inert particle into a polymer matrix can improve the
antimicrobial efficiency by agent-controlled release. There are different alternatives
to incorporate or tailor the activity in packaging films by using carrier particles and
active agents. Recent reports on these methodologies applied to polyolefin matrices
have been analyzed in the following systems: cellulose/nisin (Lu et al. 2018), cellulose/titanium oxide (TiO 2 ) (Shah and Pandey 2017), starch/sorbitol (Pirooz et al.
2018), as well as wood flour and molecular sieves with biologically active substances of EOs (Urbankova et al. 2015).
2.5.2 Biocidal Activity by Incorporating Inorganic Particles
The use of inorganic particles as polyolefin reinforcements to develop composite
and nanocomposite materials is widely known. These fillers improve the mechanical performance of polymeric materials, as well as modify their permeability and,
depending on particle nature, may include functionalities or specific activity to the
polymer. In this sense, the particles can be ‘active’ themselves or act as a carrier/
support of active agents.
To prevent or reduce the growth of microorganisms in foods, antimicrobial packaging made from active films can be used. Many research papers related to this topic
have recently been published, which have focused on polyolefin-based nanocomposites and inorganic particles. In this regard, Ag NPs have been widely used due to
its high efficiency as a toxic agent for different microorganism strains. Its high antimicrobial effectivity can be associated with the large surface area of these particles,
which allows a close interaction with microorganism cells (Carbone et al. 2016).
The antibacterial activity is the result of various processes that can have an adverse
effect on protein synthesis and DNA, or involve cell damage (Cavaliere et al. 2015).
Ag NPs also have the ability to absorb and decompose ethylene, which has a positive impact on the food shelf-life, mainly on fresh vegetables and fruits (Bratovčić
et al. 2015). On the other hand, another advantage of Ag NPs is the good thermal
stability, which allows a wide range of polymer processing alternatives
(Beigmohammadi et al. 2016). Similarly, TiO 2 NPs are commonly used in different
fields because of its self-disinfecting property. TiO 2 induces the inactivation of
pathogenic bacteria, promoting phospholipid peroxidation of microbial cell membranes (Bodaghi et al. 2013). Meanwhile, copper (Cu) NPs have biocidal properties,
which present a wide range of action against bacteria and molds, adding a good
cost-effective relationship (Kalatehjari et al. 2015; Xiong et al. 2015). Although this
2 Active Packaging Films Based on Polyolefins Modified by Organic and Inorganic…