## 3 Results and Discussion
### Volatiles
The same was observed in the case of dry wine made from FSS [10]. It is a monoterpene ketone, which is usually related to the presence of weed impurities, such as _Tanacetum vulgare_ L. (tansy) commonly growing in vineyards [10; 29]. However, the fact that it was found in all vinegar samples and dry wines made from FSS, indicates a correlation with either the fermentation process or the presence of grape seeds in FSS and should be further investigated by analysis of the FSS, other parts of the vine plant, and the seedless commercial Corinthian currants (fresh and dried), from which the FSS was generated. With respect to lactones, 4 \(\gamma\)-lactones, \(\beta\)-angelica lactone, and \(\delta\)-octalactone were identified, as well as 2-hexene-1,4-lactone, which has not been previously reported in grapes, wines or vinegar. In total, fewer volatiles were detected in the FSS vinegar compared to the dry FSS wines (160 compounds) previously reported by [10]. However, several compounds were only detected in the vinegar and the FSS analysed in this study: ethyl formate, benzyl acetate, 3-methyl-2-butten-1-ol, formic acid, 3-methyl-2-buttanone, 2-methyl-2-buttenal,hydroxyacetone, acetoin acetate, 1-hydroxy-2-butanone, phoracanthal, acetophenone, 2-acetylpyrrole, 2-hydroxyacetylfuran, eucalypt, L-menthol, 4-ketoisophorone, p-cymen-8-ol, \(\gamma\)-octalactone, 2,6-dimethylpyrazine, 2-ethyl-6-methylpyrazine, 2,3,5-trimethylpyrazine, 2,3-dimethyl-5-ethylpyrazine, 2,3,5,6-tetramethylpyrazine (ligustrazine), and benzodia-zole (Table 3). Among these compounds, the benzenoids and terpenoids originate from the phenylpropanol/benzenoid pathway and the terpenoid pathway in plants, respectively [10; 30]. A wide range of acids, aldehydes, ketones, alcohols and esters are present either as lipid degradation products of plant metabolites or as microbial metabolites generated during the fermentation processes involved in vinegar production. Pyrazines, furans, and benzothiazole are known products of the interactions of amino acids and sugars (Strecker degradation and Maillard reaction). They commonly occur in raisins due to the drying process [10; 30; 31]. However, compounds such as pyrazines may also be generated by de novo biosynthesis from microbial cultures [30]. Benzothiazole has also been reported as a result of the thermal processing of Chinese vinegar [32]. Ligustrazine has been associated with the antioxidant, antimicrobial and other health benefits of vinegar [22]. Regarding L-menthol, 4-ketoisophorone, and p-cymen-8-ol, they have not been previously reported in vinegar. Eucalypt is usually present in wines from vineards in the vicinity of eucalyptus forests [33]. Several studies have also suggested that it can be produced by the chemical transformation of limonene and \(\alpha\)-terpineol and this may explain its presence in wines from wines not grown near eucalypttus trees [34]. However, its identification along with L-menthol and phoracanthal, which is a pheromone of Phoracantha spp. (eucalyptus borers), also correlates to eucalyptus trees. Since the Corinthian currants used in this study are cultivated away from the coast where eucalyptus trees grow, the presence of these compounds should be further investigated. To conclude, comparing the different products, it can be observed that higher amounts of esters (\(\sim\)62% of identified compounds) were found in vinegar made with immobilized cells, than that made with free cells (41-55%). The percentages of esters found in the vinegar were 8 times higher than those identified in the raw material (FSS) [10]. On the other hand, higher percentages of alcohols (\(\sim\)28%) were identified in the vinegar made by free cells of the wild AAB culture (FCW), while all other vinegar samples and FSS had similar percentages (in the range 9-18%). The percentages of organic acids were similar in most samples (15-23%), except for the vinegar prepared by free cells of the selected, mixed culture (FCM) (43%).