## 3 Results and Discussion
### Volatile Compounds Obtained from Apple Juice and Dependence on the Maccration Time  
The first step in the traditional production line for apple wines is the production of apple juice prior to fermentation. In traditional Austrian rural fruit processing companies, it is common practise to start the fermentation procedure immediately after pressing, with the exception of the potential addition of pectolytic enzymes to the mash to increase the juice yield, in particular for fruits that have been stored for a longer period of time. In contrast, it is common practice in wine technology to perform maccration of the grapes with or without addition of specific enzymes to extract valuable components from the fruit flesh or the skin into the must before fermentation [18; 30]. In many cases, enzymes with glycosidic activity are added to release glycosidically bound aroma compounds into the grape juice. In this study, we followed this practice by adding an oenological enzyme with pronounced \(\beta\)-glucosidaseative activity to the apple mash and following the development of volatile and potentially aroma active compounds in the juice over a period of eight hours. We were unable to confirm our initial assumption that this would lead to an increase in the floral, rose-like flavour in _Ilzer Rose_ juice and wine, in a manner similar to the release of terpenids from their glycosides as observed in aromatic grape varieties. The observed increase in terpene-concentrations upon enzymatic treatment was far too low for a significant impact of the overall aroma [19]. Nevertheless, the maccration of the apple mash with the addition of \(\beta\)-glucosidaseade led to a significant change in the volatilome of the _Ilzer Rose_ apple juice. A total of 70 volatile compounds was identified in the juice (Table 1). The volatilome is dominated by alcohols, esters, short chain fatty acids and carbonyl compounds. The relative concentrations of the compounds given in Table 1 clearly show that maccration of the mash prior to pressing already impacts the composition significantly after two hours of maccration with a further increase in concentration for several compounds during longer maccration times. Strong increases could be observed for esters (8.5-fold increase in the total ester concentration within 8 h of maccration) and alcohols (threefold increase in total alcohol concentration after 8 h of maccration), whereas for carbonyls, free acids and terpenids only small concentration changes were observed. The highest concentration increases were found for the C\({}_{6}\) alcohols 1-hexanol, 3-hexenol (\(Z\)) and 2-hexenol (\(E\)), for the corresponding acetates and the hexyl esters hexyl hexanoate and hexyl 2-methylbutanoate. The observed increase in concentration is not, however, derived from their release from glycosides, but most probably from the lipoxygenase pathway upon cell disruption and contact with oxygen and the acidic catalysed formation of the corresponding esters in the mash. Having the odour properties of these compounds in mind (i.e., fresh green, grassy, leafy for the alcohols and green, fresh, fruits, apple- and pear-like for the mentioned esters), their concentration increase will impact the fruity character of the juice that is further processed. Consequently, the mash was macerated for eight hours to produce apple wines AW2 and AW4, to take advantage of these reactions.