# Effect of Chitosan Nanoemulsion on Enhancing the
## 4 Discussion
These functional molecules play a synergistic role along with the chitosan and alginate-based edible coatings and retain the moisture and antioxidant potential, enhance the activity of antioxidant enzymes, reduce the activity of browning enzymes, and impart antimicrobial properties in fresh fruit and vegetables. All these properties help in sustaining the appearance, lowering the senescence, and extending the life of the coated fruit and vegetables [47]. In this study, the effects of chitosan nanoparticle-containing coating on enhancing PAL, glutathione peroxidase (GPOX), and different antioxidant fractions were demonstrated. Our results show that chitosan-based coating acts as a physical barrier for the gases and water vapor [49] and enhances the anti-stress and antioxidant properties of the fruit. The role of chitosan nanoparticles in decreasing decay extension is related both to the direct antifungal activity of the chitosan and the activation of different resistance mechanisms and anti-stress systems [50]. The quality of fruit is defined by its characteristics, such as shape, size, color, and lack of defects, including cuts and decay [42]. The appearance of the product is the most important index affecting the marketability and the presence of any signs of contamination and decay and softening of fruit reduces the market demand of the product. The decay organisms can extend and grow on the surface of shrunken, wilted, injured, and softened fruit. Therefore, reducing the senescence and deterioration rate prevents the growth of decay symptoms and maintains the appearance and market demand of the product [51]. Our results indicate that ECNPC can decrease decay extension in raspberries during storage resulting in the safety and postharvest life enhancement. The results of this study showed that with an increase in the concentration of chitosan nanoemulsion, the decay extension rate was better controlled and fruit treated with 5 g L\({}^{-1}\) chitosan nanoemulsion showed the lowest decays. Chitosan acts as an active substance at the surface of fungal and bacterial cells, which makes them more permeable [52]. This interaction is mainly assumed to be electrostatic and occurs among the positive loads of chitosan amino acids and negative loads on the cell surface of microorganisms [53]. In general, the permeation of the cell surface causes the leakage of intracellular material and thereby causing cell death [54]. Phenolic compounds, including different polyphenols, flavonoids, and anthocyanins, are powerful antioxidants and antipathogen compounds, and a coating containing chi tosan nanoparticles is able to restrict decay extension directly as a natural fungicide and indirectly as a resistance mediating elicitor [55]. Phenolic compounds are one of the most important secondary metabolites and are chemically very diverse; their biosynthesis is initiated with the phenylalanine, tyrosine, and tryptophan amino acids [56]. Anthocyanis also play the most important role in raspberry fruit color and overall quality. Phenolic compounds of raspberries inhibit liposome oxidation in the body. These compounds also have significantly shown a high capacity to eliminate singlet oxygen (free radical) or act as a hydrogen supplier [57]. The powerful antioxidative and anticancer activities of raspberries phenolic antioxidants in the human body have been well demonstrated [58]. After harvest, the concentrations of phenolic and flavonoids compounds are either substantially fixed or decreased [59]. As a novel and interesting finding, in this study, we found that chitosan nanoemulsion coating substantially enhances the biosynthesis and accumulation of different phenolic contents including total phenolics, flavonoids, and anthocyanin contents of the raspberry fruit during storage, resulting in an enhanced health-promoting capacity of the fruit. Moreover, these compounds, by detoxifying the free radicals and ROS, act as anti-stress and anti-senescence agents in the fruit resulting in enhanced postharvest life and quality maintenance.