## 3 Results and Discussion
### Contents of Phenolic Compounds in Croatian Wines
#### 3.1.1 Phenolic Acids in Selected Red and White Wines
In this work, the polyphenols of Syrah wine of Croatian origin were identified and quantified for the first time. In comparison with the results of the analysis of polyphenols in Syrah wines from China and Brazil, a common dominance of the proportion of hydroxybenzoic acids is observed, but with mutual differences in their individual concentrations [37; 42]. The grape variety Blauer Portugieser is grown mainly in the small region of Plesivica on the Croatian mainland and is used to produce young wine, which is traditionally consumed immediately after fermentation [43]. The wine sample from the Plesivica Hills (rPM), along with Cabernet Sauvignon from the extreme south of the Croatian coast (rCD), is another of the red wines studied with somewhat lower phenolic acid levels. Gallic acid was the most abundant phenolic acid (25.1 mg/L), followed by syringic acid, caffe acid, and \(p\)-coumaric acid with values between 4.7 and 7.4 mg/L. This is the first information on the composition of phenolic acids in this wine variety of Croatian origin. A recent study of several samples from the same subregion showed that the total content of polyphenols and stilbenes decreases with aging and that consumption of young Blauer Portugieser is preferable [43]. An analysis of wine samples from Northern Serbia also showed that the content of phenolic acids in Blauer Portugieser, especially gallic acid, decreases with wine aging [44]. In addition, the gallic acid content in samples of this wine variety from neighboring Hungary averaged 43.0 mg/L, with a high standard deviation indicating high variability of the content [45]. Pinot Noir from the Slavonia region (rPK) was characterized by a high level of hydroxybenzoic acids, primarily gallic acid (57.9 mg/L). [PERSON] et al. [46], who studied samples of different origins on the Belgian market, also found high levels of gallic acid in this type of wine. Samples from France, Italy, Argentina, and Chile contained 122.1-223.1 mg/L of quantified phenolic acids, of which 23.4-105.3 mg/L was gallic acid. Istrian Malvasia is an autochthonous Croatian white grape variety grown mainly on the Istrian Peninsula. It is known as Malvazija Istarska in Croatia and Malvasia Istriana in Italy [47]. The percentage of quantified phenolic acids in the sample of Istrian Malvasia from western Istria (wMD) was 6.3 mg/L, dominated by \(p\)-hydroxybenzoic acid, \(p\)-coumaric acid, and caffe acid. In contrast to the results of a recent study by [PERSON] et al. [6], our sample contained significantly less phenolic acids. Table 3 shows that the wMD sample of Istrian Malvasia is more similar in its phenolic acid composition to the sample of the Malvasia Bianca Lunga variety from southern Dalmatia (wMA) than to the other sample from northern Dalmatia (wMS), which is characterized by a low content of hydroxycinnamic acids and a higher content of hydroxybenzoic acids, especially gallic acid (2.3 mg/L), just like the Italian white wine of the Malvazija family [48]. In Croatia, the grape variety Malvasia Bianca Lunga (Malvasia del Chianti) is known as Marastina. It is an old white grape variety grown mainly in the coastal regions of Croatia (Dalmatia). The aroma components of Marastina wine have already been researched [49], but as far as we know, this work provides the first information about its polyphenolic components. Other white wines contained significant amounts of caffeic acid (1.5-8.7 mg/L) and \(p\)-coumaric acid (1.5-4.4 mg/L). In addition, white wine samples of Sauvignon Blanc (wSD), Traminer (wTI), and Rhine Riesling (wRD) contained gallic acid at concentrations of 2.4-4.0 mg/L. The content of \(p\)-hydroxybenzoic acid was also significant in most of the tested wines, except for Sauvignon Blanc (wSD), Traminer (wTI), and Welschriesling (wGK) from the Slavonia and Croatian Danube regions. Regarding the total amount of phenolic acids quantified in wSD, our results are in agreement with a previous study on Spanish Sauvignon Blanc wine [50].