# Sustainability in Bio-Based Edible Films, Coatings, and Packaging for Small Fruits
## 5 Edible Film and Coating Functionalities Important for the Small Fruit Industry
### Bioactivity of the Edible Films and Coatings
#### 5.1.3 Anti-Enzymatic Capacity  
One of the leading causes of loss of fruit quality during storage is oxidative stress in plant cells. Many biotic and abiotic factors contribute to the excessive increase of reactive oxygen species (ROS) and, thus, to the disturbance of the oxidation-reduction balance of cells. ROS causes oxidative damage to cell components and alters the permeability and  
Figure 7: Schematic representation of antioxidants used in the production of edible coatings. integrity of cell membranes [170]. As a result, this leads to a reduction of enzymatic and no enzymatic antioxidant activity and, consequently, to a deterioration in the quality of the fruit. The first line of defense in plant cells against oxidative stress involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), or ascorbate peroxidase (APX). These enzymes help maintain reactive oxygen species at safe levels, essential for protecting cells from damage. Keeping ROS at an optimal level can significantly improve the storability of fruits, delaying spoilage and extending freshness. On the other hand, other essential enzymes produced by plants in response to insects and pathogens include phenylalanine ammonia-lyase (PAL), peroxididases (POD), and polyphenol oxidase (PPO) [171]. Moreover, the PPO is an enzyme associated with browning and quality degradation in stored fruits. Therefore, it is desirable to inhibit its action. Many scientific studies have shown that edible films/coatings are an alternative method of extending the life of fruit after harvest. The films/coatings constitute a barrier to water loss and volatile aromas, exhibit antioxidant activity, and prevent browning and gas exchange, reducing the rate of oxidative reaction during storage. Edible films and coatings can be carriers of active substances such as antioxidants, antibacterial compounds, and enzyme inhibitors. Due to the nutrients, vitamins, or minerals in their structure may also have health-promoting functions [16; 48; 109]. [PERSON] et al. [172] investigated the effect of 1% and 2% chitosan coatings on the enzyme activity of three selected strawberry varieties stored in cold conditions. Chitosan-coated fruit showed significantly lower lipoxygenase (LOX) activity than control fruit in all the analyzed cultivars. Although catalase (CAT) and ascorbate peroxidase (APX) activities in chitosan-coated strawberry fruits also decreased during cold storage, this decrease was smaller than in fruits without chitosan coating. Moreover, chitosan coating significantly delayed PPO and guaiacol peroxidase (GPOD) activity. The use of edible films/coatings incorporating bioactive components has emerged as an effective method for prolonging the shelf life of perishable fruits by modulating enzymatic activity. These coatings can either inhibit enzymes responsible for spoilage or promote the activity of antioxidant enzymes that protect the product from degradation. The investigation obtained by [PERSON] et al. [136] showed that bacterial cellulose coatings (CNF) infused with chia seed mucilage (CSM), a by-product of chia processing, demonstrated inhibitory effects on both PPO and POD activities, reducing browning and spoilage rates. The activity of PAL was also significantly reduced by using coatings, especially the one containing bacterial cellulose. Whereas the activity of SOD in the control and CSM- coated strawberries was considerably higher than in the other samples [136]. The study by [PERSON] et al. [141] focused on developing biodegradable coatings based on a combination of natural polymers like chitosan, gelatin, starch, and sorbitol, with and without the addition of monoterpenes (geraniol and thymol). These coatings also aimed to enhance the shelf life and quality of strawberries. The activity of followed enzymes, guaiacol peroxidase (GPX), polyphenol oxidase (PPO), and catalase (CAT), were investigated in the experimental fruits, and they were compared with that of controls.