# 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
#### 5.1.2 Antioxidant Properties  
The ability of edible films/coatings to maintain and enhance the antioxidant activity (Figure 6) of fruits is closely tied to their role in modifying physiological processes such as limiting respiration, reducing ethylene production, and delaying ripening. In many studies devoted to determining the antioxidant properties of edible films, the ability to scavenge DPPH (2,2-Diphenyl-1-picrylhydrazyl) and/or ABTS (2,2\({}^{\prime}\)-azino-bis (3-ethylbenzothazoline-6-sulfonic acid)) radicals and the iron-reducing antioxidant capacity (FRAP) are most often used. The most effective method of extending the shelf life of small fruits is to use a polymer matrix with the addition of antioxidant compounds. [PERSON] et al. [133] investigated the effects of pre-harvest foliar applications of chitosan (2.0% and 3.0%) and post-harvest coatings of _Aloe vera_ gel (25% and 33%) on the antioxidant activity of table grapes during storage. The results showed that the foliar application of 3.0% chitosan with a 33% _Aloe vera_ gel coating extends the storage life of fruit up to 15 days by significantly maintaining antiradical activity against DPPH. [PERSON] et al. [136] investigated the effect of chia seed mucilage (CSM)--bacterial cellulose nano-fiber (CNF) edible coating on bioactive compounds and antioxidant enzyme activity of strawberries. The antioxidant activity of uncoated and coated samples, assessed by the DPPH method, decreased during storage. The use of CSM-CNF edible coatings preserved the antioxidant activity of strawberries, and this effect was more evident in the CSM-coated sample containing 0.8% cellulose nano-fiber. The study by [PERSON] et al. [128] aimed to compare the effects of different types of coatings--chitosan-based (CH) and alginate-based (AL) enriched with inulin, oligofructose, and apple or orange fibers--on the quality and shelf life of blueberries. The study also evaluated the antioxidant activity of blueberry samples using the DPPH scavenging assay, focusing on the effects of chitosan-based (CH) and alginate-based (AL) coatings. The results showed that CH-based coatings were more effective in consistently enhancing antioxidant activity throughout storage when enriched with fibers than AL-base coatings. The antioxidant effect of active films based on blends of gelatin and/or chitosan containing different bioactive agents (hop extract, hop \(\alpha\)-acids, or hop \(\beta\)-acids) using DPPH and FRAP assays was investigated by [PERSON] et al. [167]. The films containing \(\beta\)-acids showed the highest antioxidant potential, followed by those containing \(\alpha\)-acids, films containing hop extract, and finally, the control films. According to the findings of [PERSON] et al. [131], coating blue honeyuckle (_Lonicera caerulea_ L.) with 1% chitosan (CH) and 30% _Aloe vera_ gel solution significantly increased their antioxidant capacity, as assessed by DPPH, ABTS, and FRAP assays. The authors  
Figure 6: The edible coating containing antioxidants acts as a barrier against ROS. ROS (reactive oxygen species), e- (electron). observed that coating with CH, _Aloe vera_, and CH + _Aloe vera_ significantly enhanced the fruit's antioxidant capacity. This improvement contributed to an overall enhancement of the fruit's quality during storage. In another study, the DMPD (N,N-dimethyl-1,4-phenylenediamine) radical scavenging method was applied to evaluate the antioxidant potentials of the extracts of strawberries chitosan coated with incorporated with gelatin, starch, and sorbitol with or without monoterpenes (geraniol and thymol) formulation (T1-T7) [142]. Among the coatings, the one that incorporated 0.02% thymol (T4 and T5) was the most effective in terms of antioxidant activity. [PERSON] et al. [143] explored the potential of chitosan (CS) derivatives conjugated with gallic acid (GA) as edible coatings for perishable fruit shelf life. The resulting CS-GA conjugate films exhibited excellent antioxidant properties ((DPPH method) compared to CS films.