# Effect of Chitosan Nanoemulsion on Enhancing the
###### Abstract  
Due to high water content and perishability, the raspberry fruit is sensitive to postharvest fungal contamination and postharvest losses. In this study, chitosan was used as an edible coating to increase the storage of raspberries, and nanotechnology was used to increase chitosan efficiency. The fruit was treated with an emulsion containing nanoparticles of chitosan (ECNPC) at 0, 2.5, and 5 g L\({}^{-1}\), and stored for 9 d. Decay extension rate, fruit phytochemical contents, including total phenolics, flavonoids, and anthocyanin content, phenylalanine ammonia-lyase (PAL), and guaiaacol-peroxidase enzymes and antioxidant activity, and other qualitative properties were evaluated during and at the end of storage. After 9 d of storage, the highest amounts of phenolics compounds, PAL enzyme activity, and antioxidant activity were observed in fruit treated with ECNPC at 5 g L\({}^{-1}\). The highest levels of total phenol, PAL enzyme activity, and antioxidant activity were 57.53 g L\({}^{-1}\), 18.88 umol/min _trans_-cinnamic acid, and 85.16%, respectively. ECNPC can be considered as an effective, safe, and environmentally friendly method for enhancing fruit phytochemical contents, postharvest life, and health-promoting capacity. ed 2021 202  
fruit production [6]. The decrease in nutritional properties and marketability of fruit and vegetables during postharvest handling and storage causes significant economic damages to the producers [7]. On the other hand, with the increase in public awareness regarding the adverse effects of the use of chemical residues on human health and environmental safety in recent years, there has been a lot of growth in the market for the demand for organic and chemical-free horticultural products [8]. However, products produced for fresh consumption are highly susceptible to major mechanisms of losses, including, enzymatic bleaching, water loss, and microbial contamination [9]. To increase the postharvest shelf life of harvested fruit and vegetables, there are some useful treatments, including modified atmosphere storage, changed atmosphere packaging, edible coatings, and the use of different natural compounds [10]. Among the treatments mentioned, the use of edible coatings is one of the promising methods for preventing water loss, decreasing metabolic and enzymatic activities and maintaining the aroma and flavor of the crops; because of a relative permeability to different respiratory gases, these coatings prevent the adverse effects of common modified atmosphere storages and packages, such as creating an unpleasant odor and smells [7]. Edible coatings are renewable compounds, including lipids, polysaccharides, and proteins, which are responsible for decreasing the exchange of water vapor, gases, etc., and many compounds used in postharvest technologies such as antimicrobial agents, antioxidants, dyes, and authorized food additives can also be added to them [11]. In addition, a new approach for enhancing fruit phytochemicals, quality attributes, and postharvest life is the use of natural compounds, such as plant growth regulators (PGR) and phytohormes as alternatives to chemical treatments during the production and postharvest stages of food crops [12; 13]. Chitosan is a polymer of (4,1) \(\beta\)-N-acetyl-d-glucosamine derived from the chitin of crustaceans, insects, and fungi, which can play an important role in the physiology of plants and harvested crops [14]. It can be used as an edible coating for many harvested horticultural products [15]. In addition to having semi-permeability behavior against respiratory gases, resulting in decreased respiration and metabolic activities, chitosan has direct antimicrobial, bactericidal, and antivirus properties that reduce the need for the use of chemical compounds and increase the safety of the food products [15; 16].