**5. Incorporation of EOs in active packaging system as antioxidant agent**

Food oxidative damage is initiated by the interactions of reactive oxygen species (ROS) including superoxide radicals (O2 <sup>2</sup><sup>−</sup>), hydrogen peroxide (H2O2), and hydroxyl radicals (OH<sup>−</sup>) with oxidizable compounds. Food oxidative damages usually are implicated in shortening food shelf life, loss of color, odor, and flavor and lowering nutritional value [80].

Amorati and his collaborators [81] have defined an antioxidant compound by its ability to slow or retarding the oxidation of another material allowing protection from oxidative stress. Antioxidants can be classified into two main groups (preventive antioxidants and chain-breaking antioxidants) depending on their mechanism

of action. Preventive antioxidants inhibit the initiation of radical species formation processes such as enzymes (catalase and superoxide dismutase) and metal chelators (phytic acid) [81]. Chain-breaking antioxidants inhibit or block autoxidation by reacting speeder than oxidizable substrate, forming neutral chemical species that cannot propagate the oxidation chain [81].

Thermoplastic films are used in packaging to exclude oxygen, avoiding the interaction between ROS and foods [82]. Nevertheless, using Thermoplastic films generates nondegradable packaging waste, and many new laws were proposed to reduce or ban single-use plastics [83].

Many previous studies have reported that EOs have a potential antioxidant activity contributing in the attenuation of free-radical oxidative reactions [13, 84]. EOs can prevent lipid oxidation in food through the inhibition of the food oxidative initiation, terminating peroxides, blocking the formation of singlet oxygen [85, 86].

Even though the large chemical diversity of EOs composition, the main components of common EOs can be classified into two structural families: terpenoids (monoterpene, sesquiterpene, diterpene) and phenylpropanoid [81]. Both terpenoid and phenylpropanoid contain phenolic compounds, which are antioxidants owing to their high reactivity with peroxyl radicals [87]. Moreover, phenolic compounds, ethers, aldehydes, ketones, and certain alcohols can enhance the antioxidant properties of the EOs [88]. Eugenol and carvacrol are also reported to be potential antioxidant agents [20].


#### **Table 3.**

*Incorporation of EOs in active packaging system as antioxidant agent.*

### *Application of Essential Oils on Active Packaging Systems DOI: http://dx.doi.org/10.5772/intechopen.113069*

EOs are mixtures of many compounds including different types of antioxidants or oxidizable components such as terpenoids and phenylpropanoid often coexist. Many previous works tried to study if the overall antioxidant activity of a natural EO can be attributed to the most effective antioxidant component. This hypothesis is true in some cases. However, many exceptions were found, reporting that EOs antioxidant activity is the result of the complex interaction among the oxidizable material to be protected and components. Generally, synergistic or antagonistic behavior is expected, depending on the composition of EOs and experimental conditions [89]. To prolong shelf life and prevent autoxidation of edible product, EOs characterized by their potential antioxidant activity can be used as a food ingredient, either as a part of active packaging. According to (EC) No 1333/2008 [90, 91]. EOs are considered as food additives when they represent a "substance not normally consumed as a food in itself and not normally used as a characteristic ingredient of food, whether or not it has nutritive value, the intentional addition of which to food for a technological purpose in the manufacture, processing, preparation, treatment, packaging, transport or storage of such food results, or may be reasonably expected to result, in it or its by-products becoming directly or indirectly a component of such foods". Moreover, EOs can also be considered as flavoring substances, according to (EC) No 1334/2008 [92] when they are 'products not intended to be consumed as such, which are added to food in order to impart or modify odor and/or taste; or products made or consisting of the following categories: flavoring substances, flavoring preparations, thermal process flavorings, smoke flavorings, flavor precursors or other flavorings or mixtures there of'. Many recent researches reported the efficiency of EOs used in active packaging as an antioxidant are reported in **Table 3**.
