## 3 Edible Coatings
### Active Edible Packaging
#### 3.4.2 Active Compounds from Plant Extracts as Additives for Edible Coatings  
Increasing research interests in plant extracts aim to develop new edible coatings for food preservation. For this reason, in recent years, active packaging containing natural biopolymers and plant extracts that can effectively delay the oxidation and microbial spoilage of food has been developed [127]. Antioxidants and antimicrobial compounds that occur naturally in some plants play a significant role in maintaining food quality [128]. In the case of fruits, the main causes of postharvest diseases are bacterial and fungal infections,as well as damage. The developed strategy of covering the fruit with edible coatings to prevent and reduce postharvest diseases combines active additives such as natural extracts, biological inhibitors, or antimicrobial chemicals [75]. The conducted research shows that the use of pomegranate peel extract for edible coatings made based on alginate and chitosan reduced the development of _Colletotrichum gloeosporoides_ strains and also inhibited the growth of _Penicillium digitatum_ on oranges covered with a coating made of chitosan, locust bean gum, and pomegranate peel extract [129]. On the other hand, the moringa leaf extract present in coatings containing carboxymethylcellulose reduced the rate of ripening and inhibited the growth of postharvest avocado pathogens [130]. [PERSON] et al. [131], covering apples of the \"Jonagored\" variety with a pullulan and a pullulan coating containing basil extract, noticed that the coating had an impact on visual factors: apples covered with a coating with the addition of basil extract were dull and had a noticeable basil aftertaste. In addition, the pullulan coating with basil extract showed good antifungal protection against _Rhizopus arrhizus_. In addition, it was observed that the weight loss of apples was significantly lower compared to uncoated apples after 30 days of storage at refrigerated temperature. Fruits and vegetables coated with propolis additives retain the appropriate level of vitamin C or flavonoids during storage, contributing to higher antioxidant activity of fruits and vegetables compared to uncoated ones. In addition, relatively higher peroxidase activity is maintained in postharvest fresh produce [132]. Significant antioxidant and antimicrobial properties were also observed when using phenols as functional compounds in edible coatings, showing the important role played by plant extracts in extending the shelf life of food, as well as maintaining the appropriate level of nutrients in many fruits and vegetables [133].  
The last few years have also seen an increasing trend of adding essential oils as active compounds in edible coatings, which are secondary metabolites produced by plants, to edible coatings, which have been applied to, for example, fresh fruits and vegetables. Essential oils are an alternative to chemical preservatives and are described as effective methods to preserve the postharvest quality of fruits and vegetables, but they modify their taste, which is often not preferred [134]. However, mixing essential oils with other substances or using multi-layers may reduce unfavourable odours and create active coatings. [PERSON] et al. [135] created an active and intelligent triple-layered edible packaging material based on the combination of furcllaran, chitosan, gelatin hydrolyses, curcumin, and lemongrass essential oil that can be used as indicators of food product freshness. Plant extracts, which are pure compounds, as well as standardised extracts, affect the control of microbial growth [136].