# Effect of Postharvest UVB Irradiation on the Fruit of cv. Dottato (_Ficus carica_ L.)
## 3 Results and Discussion
### Chemical Analysis
#### 3.2.3 Individual Polyphenolic Content  
The phenolic content of fig fruit (cv. Dottato) detected by HPLC analysis is shown in Figure 7. The main compounds detected in the skin and the flesh were 4 flavonoids (isoschaftoside; schafoside, quercetin-3-O-rutinoside also known as rutin, and quercetin-3-O-malonyl glucoside) and 2 phenolic acids (5-O-caffeoylquinic acid and caffeoylmalic acid), confirming previous work that identified them as the main classes of phenolic compounds detected in different tissues [72]. All phenols traced in the skin and flesh showed a similar general trend over time: an increase after 7 days of storage, and a decrease at T2 except for +UV60. In the skin, at T0, statistically significant differences were observed in caffeoylmalic acid, quercetin-3-O-malonyl glucoside, and schafoside, where the two treatments (+UV10 and +UV60) had higher values than the controls (Figure 7A,D,E). At T1 in the two phenolic acids and rutin, the UVB treated samples showed higher values than the control. At time T2, all UVB-treated compounds recorded higher values than the controls. In particular, in +UV60, caffeoylmalic acid (9.09 mg/L), rutin (168.65 mg/L), and quercetin-3-O-rutinoside (18.98 mg/L) showed the highest values (Figure 7A,C,D). In the flesh, the concentration of all flavonoids was about 40% lower than in the skin. Our results showed that the main phenolic compounds (caffeoylmalic acid, rutin, and quercetin-3-O-malonyl) had statistically significant differences between UVB treated and control samples at both T1 and T2 (Figure 7A,C,D). The higher concentration of single polyphenols detected in the irradiated samples was in agreement with the increase in total polyphenols observed at T2 in the skin.  
Our results agree with previous studies reporting that postharvest irradiation with UV radiation of different spectra (UVA; UVB and UVC) increases the amount of total and single carotenoids and polyphenols. UVB has been used in fruits and green leafy vegetables: [PERSON] et al. [26; 73] using UVB (1.69 Wm\({}^{-2}\)) observed an increase in carotenoids in tomato skin and flesh; [PERSON] et al. [74] treating persimmon and guava fruits with UVB 2.92 kJm\({}^{-2}\) observed an increase in both total carotenoids and \(\beta\) caroten.  
Other authors found a marked effect on the phenolic profiles of peach skin and flesh after treatments with UVB 1.39 and 8.33 kJm\({}^{-2}\)[53]; in apples, a 219 kJm\({}^{-2}\) dose of UVB resulted in an increase in flavonoids [20]. The increase in flavonoids found in our study is not surprising because these compounds act as protective pigments from the damaging effects of UV radiation that include both reactive oxygen species (ROS) and UVB screening molecules [75; 76]. Several authors have highlighted the important role of photoreceptors, such as UVR8, in modulating specific metabolic pathways, influencing the expression of several genes that control UVB acclimation [21; 76]. Recent studies have suggested that the irradiation of fruit with UVB regulates the level of genes involved in flavonoid biosynthesis, as observed in peaches [21; 77], apples [78], and blueberries [79]. [PERSON] et al. [80] suggested that UV stress leads to an increase in phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthesis of phenolic compounds. It is known that in most fruits (e.g., apples, peaches, apricots, pears, quinces, citrus fruits, and figs), a higher content of substances showing biological activity is found in the skin than in the flesh [81; 82; 83; 84]. This trend was observed in our results, which, while reporting an increase in by-products in both flesh and skin, showed a higher concentration in the latter tissue. These effects could be explained by the characteristics of the skin, as the outer part of the fruit is more prone to the synthesis of phenolic compounds and represents the natural defense barrier able to mitigate UV stress [77].