## 4 Conclusions  
A total of 36 free volatile compounds were identified in the fresh grapes, including alcohols (8), esters (8), terpenes (13), ketones (2), aldehydes (3), C-13 norisoprenoids (1), and lactone (1). Dehydration technique significantly impacted the concentration of 18 free volatile compounds in the juice from dried grapes, among them 2-methyl-1-propanol, 1-butanol, 2-hexen-1-ol, 1-hexanol, ethyl hexanoate, hexyl acetate, o-cymene, linalool oxide, and terpinen-4-ol and geraniol were higher in greenhouse-dried grapes, whereas _cis_-limonene-epoxide and _trans_-limonene epoxide and \(\gamma\)-hexlactone were higher in chamber-dried grapes compared to greenhouse-dried grapes. In grapes subjected to the two drying methods, 15 glycosidically bound volatile compounds were identified. The results of PCA analysis showed that the first two principal components described 78.96 % of the variation among the observed parameters measured in the fresh and dried samples (using the two drying methods), whereby the first principal component (D1) explained 46.35% and the second one (D2) 32.61% of the total variance. The first principal component showed the domination of alcohols and aldehydes in greenhouse-dried grapes, regardless of whether it was a free or bound fraction. The second principal component contained mostly terpen and esters. In chamber-dried grapes, the dominant bound compounds were linalool, linalool oxide, and ethyl acetate. Results of our study revealed that the key aroma compound \(\beta\)-damascenone, regardless of whether it was a free or bound fraction, had a higher concentration in a slower dehydration rate. These findings will be useful in dessert wine Prosek production. Based on our study, greenhouse-dried grapes at the controlled conditions (max. temperature at 37 \({}^{\circ}\)C) may provide an improved must aroma composition for the production of Prosek wine. In opposite to that, our research showed that a chamber-drying temperature of 50 \({}^{\circ}\)C negatively influenced the concentration of some alcohols, esters, and especially \(\beta\)-damascenone. Greenhouse-dried grapes will contribute to the aroma profile of sweet and fruity descriptors dominating in the scents of over-ripe plums and stewed apple.  
The following are available online at [[http://www.mdpi.com/2076-3417/10/24/8928/s1](http://www.mdpi.com/2076-3417/10/24/8928/s1)]([http://www.mdpi.com/2076-3417/10/24/8928/s1](http://www.mdpi.com/2076-3417/10/24/8928/s1)), Table S1: Average values (\(\upmu\)standard deviation) of volatile compounds after hydrolysis (free and bound fractions).  
Conceptualization and methodology, I.B.-L. and E.Z.; formal analysis, I.H., E.Z.; investigation, I.B.-L., I.H. and G.Z.; writing--original draft preparation, I.B.-L. and J.G.K.; writing--review and editing, I.B.-L., I.H., J.G.K., G.Z., E.Z.; Supervision I.B.-L. Project Administration I.B.-L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
This study was supported by Ministry of Science and Education of the Republic of Croatia, Project \"Biotechnological Parameters of Premium-Quality Dalmatian Dessert Wine-Prosek\".  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.