# To What Extent Are the Effects of UV Radiation on Grapes Conserved in the Resulting Wines?
## 2 Results
### Effects of the Radiation Received by Grapes on the Phenolic Composition of the Resulting Wines  
A total of 45 phenolic compounds were identified in wines (Table 1), 33 of which were also found in grapes (Table 3). The most abundant phenolic group was anthocyanins, followed by flavanols, flavonoids, and hydroxycinnamic acids (in similar amounts), and finally hydroxybenzoic acids and stilbenes (Figure 1). The total concentrations of stilbenes, flavanols, flavonoids, and hydroxycinnamic acids were significantly affected by the radiation regime. The effect of UV radiation on total stilbenes and total flavanols was rather inconsistent, because the only significant differences found were those established between PB samples (and PAB\(\uparrow\) samples for stilbenes) and PA samples, whereas P samples, which received insignificant UV-B amounts [9], were not different from samples exposed to some UV-B (PB, PAB, and PAB\(\uparrow\)). The response of total hydroxycinnamic acids was more consistent, given that samples of three radiation regimes with UV-A or a combination of UV-A and UV-B (PA, PAB, and PAB\(\uparrow\)), showed higher concentrations than P samples, although differences were relatively low. The most consistent responses were those of total flavonoids, which significantly increased in PAB and PAB\(\uparrow\) samples in comparison with the remaining samples. The total anthocyanins and hydroxybenzoic acids showed no significant responses to radiation regimes.  
Figure 1: Contents of phenolic families in the wines made from grapes exposed to five different radiation regimes: P (only PAR), PA (PAR + UV-A), PB (PAR + UV-B), PAB (PAR + UV-A + UV-B), and PAB\(\uparrow\) (PAR + UV-A + enhanced UV-B). For each variable, different letters indicate significant differences between radiation regimes (post hoc Tukey test after a one-way ANOVA test using radiation regime as main factor). Means \(\pm\) SE are shown.  
Regarding individual compounds (Table 1), 18 of them (40% of the total) were significantly influenced by the radiation regime (10 flavonols, four anthocyanins, three flavanols, and one hydroxycinnamic acid). As described for the total concentrations of phenolic groups, about half of these responses (those of flavanols, the hydroxycinnamic acid, and most anthocyanins) did not reflect a consistent effect of UV radiation on wines, because (1) significant differences were found only between pairs of samples (P and PA, P and PB, PB and PAB, or PA and PAB\(\uparrow\)); or (2) P samples showed similar values to samples that had received significant UV amounts. In contrast, the responses of most flavonols and the anthocyanin delphinidin-glucoside to UV were more consistent. Specifically, the concentrations of three minor (kaempfenol-glucoside, kaempfenol-glucuron, and isorhamtein-glucuron) and four major (three quercetin-glycos and myricetin-glucuron) flavonols were higher in PAB and PAB\(\uparrow\) samples than in other regimes (at least P, but also PA and PB in most cases).  
No significant difference between PAB and PAB\(\uparrow\) samples was found for the total concentrations of phenolic families or for individual phenolic compounds (Figure 1, Table 1).  
Some comprehensive phenolic variables, such as total phenols and the bulk levels of UVACs (Table 1), showed no significant response to the radiation regime. The total polyphenol index showed significant differences only between P and PA samples, with higher values in the former than in the latter samples, whereas the remaining samples showed intermediate values.