10
mation of toxic aldehydes due to the degradation of polyunsaturated fatty acids,
making the foodstuff unacceptable for human consumption (Fang et al. 2017).
Additionally, O 2 has a significant effect on respiration and the rate of ethylene production of breathable foods, such as fruits and vegetables. It is important to remove
the residual O 2 inside the packaging when foodstuffs are very sensitive to this gas.
Even though MAP technology allows excluding O 2 , a low O 2 volumetric
concentration (0.5–5%) remains in the headspace, which can increase along the
supply chain for different reasons. In this sense, the causes can be associated with
an incomplete removal during packaging process, low quality zip, O 2 permeation
through the packaging film or O 2 released from foodstuff to reach equilibrium with
the gas phase in the headspace (Ahmed et al. 2017). The mechanism involved in O 2
scavenging is developed through chemical reactions. Iron-based scavengers are the
most widely used and their activity is triggered by moisture, since iron can be oxidized to a stable ferric oxide trihydrate complex. In the case of cobalt, it acts as a
catalyst for the oxidation of the polymer, while palladium catalyzes the oxidation of
hydrogen into water. Other scavenging agents are ascorbic acid, gallic acid, photosensitive dyes and unsaturated fatty acids.
Antioxidant releasers Taking into account the detrimental effects on food quality
due to high O 2 concentrations inside packaging, the removal of this gas is crucial in
terms of conserving the food shelf-life (Cichello 2015). In this context, the use of
antioxidants prevents lipid oxidation caused by O 2 . These compounds can be applied
directly on foodstuffs through different processing methods (dipping, mixing or
spraying). However, this can alter food quality parameters, such as color or taste,
and can affect consumer acceptance of the product. Furthermore, the antioxidant
action ends once the active compounds are consumed in the reaction, degrading
even more the food quality. Thus, the incorporation of antioxidant in the packaging
film is an interesting alternative to improve the quality of oxidation susceptible
foodstuffs. Despite the fact that synthetic antioxidants, such as butylated hydroxyanisole and butylated hydroxytoluene are the most widely used, there is a greater
interest in incorporating natural antioxidants in food packaging. With this in mind,
essential oils (EOs), plant extracts, polyphenols and tocopherols from herbs and
spices are considered to develop antioxidant packaging materials (Alonso et al.
2016; Vilela et al. 2018).
Ethylene scavengers Ethylene, is a phytohormone which is a growth stimulator,
and accelerates the ripening and senescence of climacteric fruits and vegetables in
postharvest. In addition, this gas contributes to the chlorophyll degradation and the
softening of fruits. For this reason, the elimination of ethylene from food packaging
through the incorporation of ethylene scavengers allows extending the food shelflife. These active compounds can be included by dispersing them in material packaging or incorporating them in a layer of the flexible laminated packaging (Yildirim
et al. 2018).
Y. N. Alonso et al.
mation of toxic aldehydes due to the degradation of polyunsaturated fatty acids,
making the foodstuff unacceptable for human consumption (Fang et al. 2017).
Additionally, O 2 has a significant effect on respiration and the rate of ethylene production of breathable foods, such as fruits and vegetables. It is important to remove
the residual O 2 inside the packaging when foodstuffs are very sensitive to this gas.
Even though MAP technology allows excluding O 2 , a low O 2 volumetric
concentration (0.5–5%) remains in the headspace, which can increase along the
supply chain for different reasons. In this sense, the causes can be associated with
an incomplete removal during packaging process, low quality zip, O 2 permeation
through the packaging film or O 2 released from foodstuff to reach equilibrium with
the gas phase in the headspace (Ahmed et al. 2017). The mechanism involved in O 2
scavenging is developed through chemical reactions. Iron-based scavengers are the
most widely used and their activity is triggered by moisture, since iron can be oxidized to a stable ferric oxide trihydrate complex. In the case of cobalt, it acts as a
catalyst for the oxidation of the polymer, while palladium catalyzes the oxidation of
hydrogen into water. Other scavenging agents are ascorbic acid, gallic acid, photosensitive dyes and unsaturated fatty acids.
Antioxidant releasers Taking into account the detrimental effects on food quality
due to high O 2 concentrations inside packaging, the removal of this gas is crucial in
terms of conserving the food shelf-life (Cichello 2015). In this context, the use of
antioxidants prevents lipid oxidation caused by O 2 . These compounds can be applied
directly on foodstuffs through different processing methods (dipping, mixing or
spraying). However, this can alter food quality parameters, such as color or taste,
and can affect consumer acceptance of the product. Furthermore, the antioxidant
action ends once the active compounds are consumed in the reaction, degrading
even more the food quality. Thus, the incorporation of antioxidant in the packaging
film is an interesting alternative to improve the quality of oxidation susceptible
foodstuffs. Despite the fact that synthetic antioxidants, such as butylated hydroxyanisole and butylated hydroxytoluene are the most widely used, there is a greater
interest in incorporating natural antioxidants in food packaging. With this in mind,
essential oils (EOs), plant extracts, polyphenols and tocopherols from herbs and
spices are considered to develop antioxidant packaging materials (Alonso et al.
2016; Vilela et al. 2018).
Ethylene scavengers Ethylene, is a phytohormone which is a growth stimulator,
and accelerates the ripening and senescence of climacteric fruits and vegetables in
postharvest. In addition, this gas contributes to the chlorophyll degradation and the
softening of fruits. For this reason, the elimination of ethylene from food packaging
through the incorporation of ethylene scavengers allows extending the food shelflife. These active compounds can be included by dispersing them in material packaging or incorporating them in a layer of the flexible laminated packaging (Yildirim
et al. 2018).
Y. N. Alonso et al.