## 3 Results and Discussion  
### Gc-Ms  
Major volatile aroma compounds are highly abundant in wines and for this reason GC-MS was considered appropriate for their analysis. It was considered that their quantitation by GC-MSwas not significantly affected by co-eluting compounds. As well, the analysis of major volatiles by GC\(\times\)GC-TOF-MS would require a rather different setup than that applied in this study, with much larger modulation time and hot pulse duration, not applicable for minor and trace compounds. Major volatile aroma compounds determined by GC-MS are listed in Table 1, grouped according to chemical class, and sorted within each class in order of decreasing \(F\)-ratio obtained by one-way ANOVA. Twenty-one monoterrepoids and a sesquiterpenoid _trans_-nerolidol, eight C\({}_{13}\)-norisoprenoids, two benzenoids, four alcohols, four acids, and 11 esters were quantified. Table S2 reports the concentrations of the identified volatile compounds in each of the investigated wines. Among terpen, major monoterrepoids such as linalool, geraniol, \(\alpha\)-terpineol, and nerol were found in the highest concentration, which was generally in agreement with previous findings on white wines [34; 35; 36]. The mentioned are among the most influential monoterrepoids to wine aroma, to which they significantly contribute with specific floral and fruity nuances due to their relatively low odor perception thresholds, such as, for example, 15 \(\upmu\)g/L for linalool [35; 37]. The highest \(F\)-ratio among all the compounds identified by GC-MS was determined for \(\alpha\)-terpineol, followed by an unidentified monoterpene and linalool, confirming the importance of terpen for wine varied differentiation [35]. Many other (mono)terpenes also turned out to be important in this sense, while other compound classes exhibited lower \(F\)-ratios, with the exception of 1-hexanol. Such an outcome was expected to some extent, since terpen are primary aroma compounds originating from grapes, both as free volatile molecules or released from glycosidic precursors. Their composition and amounts are genetically pre-determined: genetic variation in aroma biosynthesis genes cause differences in terpenene concentrations between grapevine varieties. For example, a variant of 1-deoxy-D-xylulose-5-phosphate synthase, a gene responsible for the biosynthesis of terpenoids, causes pronounced increase in terpene concentration in Muscat and Gewurztraminer grapes, which gives wines of these varieties a recognizable floral aroma [38; 4; 39]. Monoterpenes are generally known to be responsible for varietal aroma of muscats and non-muscat aromatic varieties, such as Gewurztraminer, Riesling, Muller-Thurgau, etc. [36; 40; 41], but were also found useful for the differentiation of wines of other, so-called semi-aromatic and neutral grape varieties [42; 43; 41; 44; 45]. [PERSON], [PERSON], [PERSON], and [PERSON] [46] characterized the volatile fraction of Andalusian sweet wines made from Muscat and Pedro Ximenez varieties and, interestingly, also found that \(\alpha\)-terpineol was the most powerful differentiator with the highest \(F\)-ratio, followed closely by linalool and limonene, similar as in this case. In this study, the ratios of terpene concentrations in different monovarietal wines varied from compound to compound, but it was generally observed that wines from Skrlet, a relatively unexplored Croatian grape variety, were characterized by the highest concentrations of many important monoterrepenes (Table 1), while the concentrations of other monoterpenes were also among the highest in the investigated wines. The concentrations of monoterpenes in Malvazija istarska wines were notable and generally in fair agreement with those reported previously for this variety, with linalool followed by geraniol as the most abundant [43; 47; 48; 49]. Malvazija was followed by Posip wine with intermediate concentrations, while Marastina and especially Kraljevina wines had the lowest terpene concentrations. \begin{table}