# Effect of Chitosan Nanoemulsion on Enhancing the
###### Abstract
Due to its semi-permeability, chitosan has a relative permeability to water vapor and is a good inhibitor of oxygen exchange, thereby altering the internal atmosphere of the product and increasing the shelf life of the product [16; 17]. As a PGR, chitosan has been shown to enhance the natural resistance mechanisms of the plants and harvested crops against different pathogens and stress conditions [18]. Moreover, the use of nanotechnology in edible coatings and packaging can increase their efficiency compared to conventional edible coatings and improve the quality of edible coatings by reducing the particle size and the pores of the coatings [19]. The small size of nanoemulsion particles has two important effects--(1) it increases the stability and physicochemical properties of the coating and (2) it can increase the biological activity of lipophilic materials by increasing the surface area to the mass unit rate [20]. Nanoemulsions enhance the bioavailability of bioactive materials [21] and the bactericidal properties of antimicrobials because they can pass as active elements across the bio-membranes [22]. Nanoemulsions are now widely used to cover, protect, and transfer lipophilic materials on foods, fruit, and vegetables [23; 24]. Raspberry are rich sources of different powerful antioxidants including anthocyanins, ellagic acid, gallic acid, catechins, camphor, and salicylic acid, with high capacity in the prevention of unwanted damages of free radicals and reactive oxygen species (ROS) to cell membranes and other structures in the human body. Previously mentioned antioxidant compounds may reduce a person's risk of heart disease by preventing platelet buildup and lowering blood pressure by anti-inflammatory agents. _Rubus_ antioxidant compounds and anti-inflammatory agents are correlated with cancer protection by reducing the reproduction of cancer tumors. Due to the high levels of antioxidant compounds such as vitamin C and polyphenols, raspberries have an oxygen-radical absorbance capacity of about 30 mM to 100 mM per 100 gr [25]. Ascorbic acid or vitamin C provides extracellular and intracellular antioxidant activity mainly by scavenging reactive oxygen species [26]. Raspberries are also a great source of riboflavin, folate, niacin, magnesium, potassium, and copper. The presence of these nutrients and their synergistic role in improving human health have led to the fact that this fruit is a good source to answer daily needs for various micronutrients (anthocyanins, polyphenols, ascorbic acid, fiber, proteins, vitamins, and minerals) [27]. This fruit is one of the most popular berry fruit, but due to very high sensitivity to different postharvest losses, such as rapid water loss, mechanical damage, and pathogen sensitivity, they have a very short shelf life, leading to rapid phytochemical depletion and quality deterioration [28]. The purpose of this research was to increase the shelf life and maintain phytochemical contents and quality of this valuable fruit with the use of chitosan nanoparticle coatings as a natural safe compound. We studied the effects of this coating at different concentrations on decay extension rate, weight loss, different quality parameters of the fruit, and different resistance mechanisms, including total antioxidant activity and different antioxidant fractions. Moreover, the effects of this coating on fruit taste and flavor as important factors determining consumer acceptance were studied.