## 3 Results and Discussion
### Contents of Phenolic Compounds in Croatian Wines
#### 3.1.3 Flavonoids in the Selected Red and White Wines  
Eight flavonoids were analyzed in the selected commercial Croatian wines. The white wines did not contain flavonoids, except for two samples of Welschriesling from Medimurje (wGJ) and Pinot Blanc from the Croatian Uplands (wPD) with traces of quercetin. In contrast to the white wines, the red wines contained various types of flavonoids in amounts up to 37.6 mg/L (Table 5). The highest amount of flavonoids tested was present in three wine varieties from the same wine region. Merlot (rMK), Cabernet Sauvignon (rCK), and Syrah (rSK) originating from the Dalmatian Hinterland contained 32.4-37.6 mg/L flavonoids. They were followed by the Croatian autochthonous wine varieties Plavac Mali (rPD) and Babic (rBS) from Dalmatia with flavonoid contents of 29.6 and 26.1 mg/L, respectively. The Plavac Mali (rPI) wine sample contained 16.9 mg/L flavonoids, which is significantly less than the previously described rPD sample of the same variety. These Plavac Mali wines are from the same subregion but from different Croatian vineyard locations. Cabernet Sauvignon (rCB) is a red wine originating from a continental wine region and is characterized by high flavonoid content (19.3 mg/L), which, however, is significantly higher than that of the sample of the same variety from Croatian I stria (rCA, 6.6 mg/L) and from the extreme south of Croatia (rCD, 7.1 mg/L). Likewise, the Merlot from Croatian I stria (rMA) contained a much lower amount of flavonoids (7.9 mg/L) than the sample from the Dalmatian Hinterland (rMK). Among the tested flavonoids, the flavonols quercetin (<LOQ--21.7 mg/L) and myricetin (2.9-12.1 mg/L) stood out in terms of quantity in all the studied red wines. As far as the content of quercetin is concerned, the order of the wines from the richest in quercetin to the poorest in quercetin is completely identical to that which we described when considering the contents of total flavonoids tested.  
Our results are consistent with some previous studies of Croatian red wines, which showed that quercetin and myricetin are very abundant flavonoids in wines made in the coastal areas [6; 14], but with large differences in their proportions. On the contrary, [PERSON] et al. [16] determined significantly lower amounts of myricetin (<2 mg/L) and quercetin (<0.5 mg/L) in autochthonous wines Plavac Mali and Teran and in non-native Merlot and Cabernet Sauvignon. Syrah wine from the Dalmatian Hinterland (rSK), which was rich in myricetin and quercetin, corresponded to samples of this variety from the 2010 and 2011 vintages in some Brazilian regions, where significant differences in polyphenol composition were found due to climatic conditions [42]. In response to solar radiation, especially UV-B, flavonoids accumulate mainly in the epidermal cells of plant tissue and filter the most dangerous wavelength of the solar spectrum for DNA [64]. Therefore, Croatian wines from the coastal regions, where solar radiation is significantly higher compared to the mainland, were richer in flavonoids. Among the studied red wines, Merlot (rMK), Cabernet Sauvignon (rCK), and Syrah (rSK) from the Dalmatian Hinterland stood out for their content. Although these wines were obtained from different grape varieties, they had very similar flavonoid compositions. The reasons for this are most likely the same location of the vineyard, exposed to high and uniform solar radiation.