Dehydration or drying of grapes is one of the most important steps in the production of Croatian traditional dessert wine Prošek. The natural sun drying of grapes is the traditionally used method in Prošek production. Alternative methods, such as dehydration under controlled conditions, have been studied as safer and faster methods than the traditional sun drying but without precise knowledge of the effect on volatile compounds. The objective of this work was to study how dehydration of grapes carried out in a greenhouse and an environmentally controlled chamber impacts on the free and glycosidically bound volatile compounds of native grape cv. ‘Maraština’. The 36 volatile compounds were identified and quantified using headspace solid-phase micro extraction coupled with gas chromatography-mass spectrophotometry (HS-SPME-GC/MS). The results showed that the aroma profile of dehydrated grapes was significantly different from that of fresh grapes. Regarding free forms, significant increases in the concentration of 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 found in greenhouse-dried grapes, whereas increases in cis-limonene-epoxide, trans-limonene epoxide, and γ-hexalactone were higher in chamber-dried grapes compared to greenhouse-dried grapes. Glycosidically bound forms of o-cymene, linalool oxide, linalool, and terpinen-4-ol were increased in both types of drying, whereas β-damascenone was increased only in greenhouse-dried grapes.

Budić-Leto I., Humar I., Zdunić G., Hribar J., Zlatić E. (2015): Volatile compounds in Prošek dessert wines produced from white and red grapes. Czech J. Food Sci., 33: 354-360.Prošek dessert wines produced from dried grapes of two native Croatian varieties, one white and one red, had complex volatile compositions. Various categories of volatile compounds were identified using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Sixty-one individual volatile compounds of Prošek were identified. Of these, nine compounds comprised over 95% of the total peak area of volatile aromas detected in Prošek: five esters and four alcohols. The remaining volatile compounds consisted of 11 alcohols, 11 esters, 10 terpenes, 8 aldehydes, 10 ketones, 4 acids, 1 lactone, and 1 norisoprenoide. Only 13 of the 61 aroma compounds showed significant differences between the varieties investigated. These results suggest that the characteristic aroma of Prošek is very complex and determined predominantly by the unique process of the grape drying.