# Postharvest Evaluations of Blackcurrant Fruits with Chitosan and Ultraviolet A Treatments
## 3 Results and Discussion
### Total Polyphenol, Flavonoid, and Anthocyanin Content Changes Under Different Treatments
It has been reported that rutin is widely distributed in vegetables and fruits, especially in tea leaves and apples, and has several pharmacological activities, such as cytoprotective, vasoprotective, anticarcinogenic, neuroprotective, and cardioprotective activities [67; 68]. Rutin with vitamin C has synergistic relations, strengthening blood vessels and promoting flexibility [52]. Only one study has mentioned that rutin was influenced by the maturity stages of redcurrant fruits, but there is no report of rutin changes during postharvest treatments in blackcurrants [69]. In this study, similar to cyanidin-3-galactoside, chitosan itself was not the main cause of rutin changes, whereas UVA caused 316 mg/g rutin changes. Luteolin, isorhamnetin, and kaempferol qualities ranged moderately in the flavanols of blackcurrants (Table 4). All these substances had reduced amounts during postharvest treatments, although the interaction results showed that the UVA, chitosan, or UVA-chitosan did not have significant differences on day 15. Luteolin, with the potential for cancer prevention and therapy, is widely found in the plant kingdom [70]. Chitosan untreated and treated sample results indicated that chitosan significantly influenced the luteolin content, decreasing the amounts from 4.2 to 2.8 mg/g on average. Chitosan as the coating materials was applied for oral delivery systems of luteolin in some research [71; 72; 73], but no research has reported chitosan's impacts on the general extraction of luteolin in vitro; further studies need to be conducted for research with the combination of luteolin and chitosan. Isorhamnetin is mainly contained in _Hippocampa rhamnols_ L. and _Ginkgo biloba_ L., having many functions in cardio-cerebral vessels and nerve protection [74]. A lower amount of isorhamnetin was also found in blackcurrant pomace [75]. In this research, about 2 to 30 ug/g isorhamnetin was found in 'Tofino' blackcurrants. Kaempferol levels in blackcurrants were low in other research, ranging from 0.9 to 2.3 mg/100 g [76]. In this study, 2 to 25 ng/100 g of kaempferol was found in 'Tofino' fruits, which was slightly higher than found in the previous publication. Kaempferol is a natural compound, modulating inflammatory activity and playing important roles in antioxidant, antidiabetic, antimicrobial, antitumor, and anticancer activities [77; 78]. It has been identified in many fruits, vegetables, and medicinal plants [79]. This beneficial flavonoid compound in 'Tofino' fruits proved the potential of blackcurrants in pharmaceutical applications. Other moderate quantities of substances, such as delphinidin, procyanidin B2, procyanidin B4, cyanidin, and quercetin, were also found in 'Tofino' fruits in this study,although postharvest storage did not influence their amounts significantly. Four main pigments, the 3-\(O\)-glucosidase and the 3-\(O\)-rutinodies of delphinidin and cyanidin, took more than 97% of the total anthocyanins in blackcurrants in previous research [80]. These moderate anthocyanin substances provide natural pigments in blackcurrants. Less than 10 ng/100 mg anthocyanins were petunidin, pelargonidin, malvidin, and peonidin from blackcurrant fruits in this research. There was no detection of cyanidin-3,5-diglucoside in 'Tofino' blackcurrants. Although the amounts of these anthocyanins were small, their roles in human nutrition cannot be neglected, attributing to their antioxidant and anti-inflammatory effects [81; 82; 83; 84]. In summary, postharvest treatments, especially UVA with or without chitosan, influenced multiple anthocyanin substances. Chitosan-based films and coatings on food could effectively extend the quality and storage of agricultural produce [85]. Their antifungal activity and fruit weight loss control capabilities were proven during blackcurrant postharvest storage in this study. UVA enhanced certain monophenol compounds, including cyanidin-3-galactosidase and rutin (Table 4), which improved the blackcurrants' nutritional values.