15
reduction in the elongation at break, transparency and water vapor permeability
values of the films were also reported by Fasihnia et al. (2018) by adding 6% w/w
of sorbic acid. In addition, the UV absorption of composite films was increased.
Kuplennik et al. (2015) also developed antimicrobial composite films from linear
low-density polyethylene (LLDPE) and ethylene vinyl acetate (EVA) containing
potassium sorbate and using glycerol monooleate as a dispersant for use as acidic
food packaging material, obtaining improved materials with antifungal efficiency
against Saccharomyces cerevisiae. Kamalipour et al. (2016) formulated antimicrobial composite films from maleic anhydride grafted-PE, medium density polyethylene (MDPE) and triclosan blends. These authors reported that antibacterial activity
against E. coli, K. pneumoniae and S. aureus was improved because of the triclosan
release rate increased due to decreased crystallinity degree and increased polarity.
On the other hand, the AP including natural antimicrobial agents have had a
growing interest at present, since consumers are focused on healthy, organic and
safe foods, avoiding the content of synthetic compounds (Bondi et al. 2017;
Khaneghah et al. 2018; Pisoschi et al. 2018; Cottaz et al. 2019). However, special
care is required during plastic processing, as most natural antimicrobials are thermolabile (Figueroa-López et al. 2019), and more expensive than traditional synthetics. For this reason, the use of natural antimicrobials effectively and efficiently is of
great interest.
The packaging success is a result of the balance between product requirements
and costs with the use of the active system. It is thus important to consider that the
relevance related to the use of antimicrobial systems in a fresh food compared to
nonperishable foodstuffs. In this context, dairy derived foods (e.g. cheese) are very
susceptible to spoilage by fungal microorganisms and their mycotoxins (Benkerroum
2016). Therefore, antifungal agents in these foods are usually incorporated into the
food bulk or on its surface. In particular, one of the most widely used natural agents
in the dairy industry is the polyene natamycin (Jalilzadeh et al. 2015). Direct incorporation of natamycin particles on PE surface and/or in situ generation of natamycin
crystal are advantageous approaches to improve antifungal performance. These surface modifications make it possible to avoid excess active agent, and consequently,
its undesirable effects on food. In line with this, antimicrobial natamycin particles
can, for example, be physisorbed or chemisorbed (linked) on the film surface
through adaptable, free adhesive, low-cost and versatile methods (e.g. spraying) for
film production (Grafia et al. 2018). Grafia et al. (2018) sprayed natamycin from an
ethanol solution and/or a n-heptane suspension to a semi-molten PE film surface. It
is worth noting that the commercially used source of natamycin is typically composed of 50% w/w of pure natamycin and 50% w/w of lactose. Considering that
natamycin is soluble in ethanol but not in n-heptane, while lactose is insoluble in
both solvents. Thus, the mechanism of natamycin inclusion on PE depends on the
solvent (Grafia et al. 2018). According to Grafia et al. (2018), during spraying of
natamycin from an ethanol solution, the lactose particles impact the heat-softened
film surface and act as nucleation points for the natamycin crystals. In contrast,
when the n-heptane suspension is sprayed, the particles impact the softened film
surface and remain attached. In both cases, the solvents are evaporated during the
2 Active Packaging Films Based on Polyolefins Modified by Organic and Inorganic…
reduction in the elongation at break, transparency and water vapor permeability
values of the films were also reported by Fasihnia et al. (2018) by adding 6% w/w
of sorbic acid. In addition, the UV absorption of composite films was increased.
Kuplennik et al. (2015) also developed antimicrobial composite films from linear
low-density polyethylene (LLDPE) and ethylene vinyl acetate (EVA) containing
potassium sorbate and using glycerol monooleate as a dispersant for use as acidic
food packaging material, obtaining improved materials with antifungal efficiency
against Saccharomyces cerevisiae. Kamalipour et al. (2016) formulated antimicrobial composite films from maleic anhydride grafted-PE, medium density polyethylene (MDPE) and triclosan blends. These authors reported that antibacterial activity
against E. coli, K. pneumoniae and S. aureus was improved because of the triclosan
release rate increased due to decreased crystallinity degree and increased polarity.
On the other hand, the AP including natural antimicrobial agents have had a
growing interest at present, since consumers are focused on healthy, organic and
safe foods, avoiding the content of synthetic compounds (Bondi et al. 2017;
Khaneghah et al. 2018; Pisoschi et al. 2018; Cottaz et al. 2019). However, special
care is required during plastic processing, as most natural antimicrobials are thermolabile (Figueroa-López et al. 2019), and more expensive than traditional synthetics. For this reason, the use of natural antimicrobials effectively and efficiently is of
great interest.
The packaging success is a result of the balance between product requirements
and costs with the use of the active system. It is thus important to consider that the
relevance related to the use of antimicrobial systems in a fresh food compared to
nonperishable foodstuffs. In this context, dairy derived foods (e.g. cheese) are very
susceptible to spoilage by fungal microorganisms and their mycotoxins (Benkerroum
2016). Therefore, antifungal agents in these foods are usually incorporated into the
food bulk or on its surface. In particular, one of the most widely used natural agents
in the dairy industry is the polyene natamycin (Jalilzadeh et al. 2015). Direct incorporation of natamycin particles on PE surface and/or in situ generation of natamycin
crystal are advantageous approaches to improve antifungal performance. These surface modifications make it possible to avoid excess active agent, and consequently,
its undesirable effects on food. In line with this, antimicrobial natamycin particles
can, for example, be physisorbed or chemisorbed (linked) on the film surface
through adaptable, free adhesive, low-cost and versatile methods (e.g. spraying) for
film production (Grafia et al. 2018). Grafia et al. (2018) sprayed natamycin from an
ethanol solution and/or a n-heptane suspension to a semi-molten PE film surface. It
is worth noting that the commercially used source of natamycin is typically composed of 50% w/w of pure natamycin and 50% w/w of lactose. Considering that
natamycin is soluble in ethanol but not in n-heptane, while lactose is insoluble in
both solvents. Thus, the mechanism of natamycin inclusion on PE depends on the
solvent (Grafia et al. 2018). According to Grafia et al. (2018), during spraying of
natamycin from an ethanol solution, the lactose particles impact the heat-softened
film surface and act as nucleation points for the natamycin crystals. In contrast,
when the n-heptane suspension is sprayed, the particles impact the softened film
surface and remain attached. In both cases, the solvents are evaporated during the
2 Active Packaging Films Based on Polyolefins Modified by Organic and Inorganic…