# Postharvest Evaluations of Blackcurrant Fruits with Chitosan and Ultraviolet A Treatments
## 1 Introduction  
Blackcurrent export values include frozen concentrate, individually quick-frozen blackcurrants, and other processed blackcurrants [1]. It was estimated that the global blackcurrant concentrate market could reach USD 3590 million by 2027 [2]. European and Asian countries contributed the most to the total production of blackcurrants [3]. The blackcurrant fribus with Chitosan and blackcurrant global market has continued to increase with rising consumer knowledge of its health benefits. The fruits are commonly utilized in drinks, jams, marmalades, gelatins, syrupps, and other foods. Blackcurrants are rich in vitamin C, antioxidants, and anthocyanins, including cyanidin-3-glucoside, cyanidin-3-rutinoside, delphinidin-3-glucose, and delphinidin-3-rutinoside [4]. Those anthocyanins are responsible for the red/purple color of juices, and their stability and properties vary depending on their structure, the pH of the medium, and the presence of other compounds. Many studies focusing on the extraction of phenolic compounds and anthocyanins from berries to juice have shown the importance of the solvent for extraction, as well as new techniques such as high-power sonication to maximize their extraction [5]. Blackcurrant polyphenol extracts have the potential in active packing to extend other fruits' shelf life [6]. Blackcurrant powder itself as a coating could assist the postharvest treatment of other fruits [7]. Its extract has antifungal activities against Botrytis cinerea Pers [8]. There were some studies on blackcurrant preharvest and postharvest. Preharvest methyl jasmonate treatment could increase ellagic acid, myricetin, and quercetin in certain blackcurrant cultivar berries and improve berry health benefits [9]. In blackcurrant postharvest treatment research, it was indicated that volatile constituents of blackcurrants, such as esters and terpene alcohols, could be changed by controlled atmosphere storage (changes with higher CO\({}_{2}\) levels and lower O\({}_{2}\) levels) compared with air-stored fruits [10]. Ozonationhas impacted the blackcurrant antioxidant status in fruits during postharvest [11]. Postharvest storage conditions also influenced the non-volatile components, including sugars and organic acids [12]. Salicylic acid and titanium dioxide nanoparticles were combined with chitosan on blackcurrants. The results indicated that all three components combined together changed the blackcurrants with the smallest effects on physiochemical changes and maintained the total anthocyanin and flavonoid contents [13]. Chitosan is a cationic polysaccharide, a deacetylation product derived from chitin [14]. Chitin can be found in many marine sources (e.g., crustaceans), terrestrial sources (e.g., cockroaches), and microbial sources (e.g., fungus) [15]. Chitosan as a natural polymer has been widely used in food preservation, processing, packaging, and additives. Chitosan modification has enhanced chitosan functions and effects [16]. Chitosan-based nanoparticles have increased the biological activities of chitosan with their low toxicity, mucoadhesion, and tunable physical properties [17]. Chitosan and chitosan nanoparticles could form a film to protect the fruits and vegetables from microbial infection, reducing weight loss and air exchange. Meanwhile, it has been reported it could increase the antioxidant activities, enhance total phenolic contents, and extend fruit and vegetable shelf life [18]. Chitosan also can be blended with other polymers to enhance its usage [19]. Biodiversity materials with chitosan and other agents in electrospinning have improved the need for multifunctional of chitosan [20]. UV radiation is another technique used in the postharvest treatment of fruits and vegetables. UVC and UVB spectrums are 100-280 nm and 280-315 nm per se. UVC and UVB, with higher energy compared with UVA, have been widely used to enhance vegetable colors with increasing chlorophyll and carotenoid concentrations, reduce microbial populations, and increase phytochemical contents and antioxidants [21].