# Effect of Postharvest UVB Irradiation on the Fruit of cv. Dottato (_Ficus carica_ L.)
## 3 Results and Discussion
### Chemical Analysis
#### 3.2.4 Principal Component Analysis  
In order to evaluate the effect of the different treatments (T0\(-\)UVB10, T0\(-\)UVB60, T0\(+\)UVB10, T0\(+\)UVB60, T1\(-\)UVB10, T1\(-\)UVB60, T1\(+\)UVB10, T1\(+\)UVB60, T2\(-\)UVB10, T2\(-\)UVB60, T2\(+\)UVB10, T2\(+\)UVB60) on the fig samples and identify the most significant variables in the data set, a principal component analysis (PCA) was performed. The results of the PCA revealed a clear clusterization of the different treatments over time (UVB treated and control samples), based on their effect on fig samples (Figure 8). The first three principal components (PCs) explained a total variance of 92.97% in the model. A plot of the percentage of variance explained by eleven PCs and eigenvalues associated with the eleven PCs is provided Figure 8A. The first principal component (PC1) explained 65.30% of total variance. Parameters with the highest positive weight on PC1 were related to sugar (total sugar, fructose, glucose, Brix\({}^{\circ}\), in the flesh and the skin) as well as pH, weight loss, and decay, whereas parameters like firmness, color parameters, and acidity had the most significant negative weight. The second component (PC2) explained 22.17% of the variability, and showed strong loadings for total polyphenols, but also for sugars and carotenoids, in both the flesh and the skin. Finally, carotenoids in the skin showed the highest contribution to the third principal component PC3, accounting for 5.50% of the variability. The comparison of the plot scores for PC1, PC2, and PC3 in Figure 8B-D  
Figure 7: Individual polyphenols in the skin (full-color columns) and the flesh (color columns with pattern) for two different treatments (+UVB10 and +UVB60) on fig fruits and relative controls (\(-\)UVB10 and \(-\)UVB60) at T0 (immediately after the treatment), T1 (after 7 days), and T2 (after 10 days) of storage. (**A**) Cafeoylmatic acid, (**B**) 5-O-caffeoylquinic acid, (**C**) Quercetin-3-O-rutinoside, (**D**) Quercetin-3-O-malonyl glucoside, (**E**) Schaftisolide, (**F**) Isoschaftisolide. Data are means (n = 3) \(\pm\) SD. The different letters above each column indicate significant differences among the treatments (Tukey’s test \(p<0.05\)), ns = not significant.  
allows for obtaining a view of the treatment dispersion and clusterization based on their effects on the fig samples. In particular, for the first two PCs, the treatments were grouped into three main groups corresponding to the different time points: 0, 7, and 10 days. The first group included treatments at time T0, the second group treatments at time T1, and the third group treatments at time T2. The distance between these groups was determined prevalently by the natural physiological change in different PC1 parameters during the storage period. Furthermore, each of these groups was composed of two subgroups: the \"control\" subgroup and the \"UVB-treated\" subgroup. The distance between these subgroups increased with time, and the most discriminating factor was the polyphenol content, but also of importance were the other parameters such as the content of carotenoids and the sugar content. The groups plotted for PC1 and PC3 were very similar to those for the PC1 and PC2 plot. In the final plot, the treatments were divided into two groups: the \"control group\" and the group \"treated with UVB\". The results obtained through the PCA analysis make it clear that UVB treatments significantly influence the physical and chemical characteristics of the treated samples, thus confirming the key role of UVB radiation in improving the nutritional qualities and shelf life of _Ficus carica_ fruits, as reported in the literature for several species [21; 23; 25; 77; 78].  
Figure 8: **(A)** Screen plot obtained from the PCA (F1–F11) denoting the eleven principal components for the total parameters studied; **(B–D)** loading plots of the first, second and third principal components showing the positions of the different UVB treatments over time and the different parameters studied.