# Comparison of Volatile Profiles of Meads and Related Uniflorl Honeys: Traceability Markers
## 2 Results and Discussion
### Traceability of Chemical Markers of Botanical Origin and Comparison with Control  
The comparison of volatile profiles of honey and meads allowed us to detect characteristic compounds that could be helpful to trace botanical origins of the honey used to produce mead and which are detectable after fermentation. In most of the samples, DHLLE extracts were found to be more useful to find such characteristic compounds. This is also related to the fact that it focuses on the less volatile compounds. In contrast, in the case of HS-SPME the main targets are the more volatile compounds present in the headspace that are partially lost during wort preparation and fermentation process. Pentanoic (valeric) acid, previously reported as a volatile marker in the headspace of buckwheat honey [16], in the current study was detected by HS-SPME in the honey and not boiled mead (0.70; 0.20%). DHLLE extracts provided a wider range of characteristic compounds for buckwheat honey: \(p\)-hydroxybenzoic acid (5.65; 3.29; 16.11%), 1-isoquinoliniccarbonitrile (1.37; 0.49; 0.93%), 1\(H\)-indole-3-acetonitrile (3.58; 0.02; 1.38%), 1\(H\)-indole-3-carboxaldehyde (3.58; 0.02; 1.38%) and \(\gamma\)-valerolactone (0.14; 0.04; 0.29%) were detected in the honey and both meads, respectively. The compounds were previously found in chromatographic profiles of this honey type and \(p\)-hydroxybenzoic acid was proposed as its potential marker [8; 17]. In canola honey, the compound that may be useful as a nonspecific marker and that was retained in both honey and meads was methyl syringae (10.55; 4.45; 9.73%). This lignin derivative is also present, however, in a number of other honey varieties [18]. DHLLE extracts retained particularly high percentages of less volatile terpenic acids: 4-isopropenylcyclohex-1,3-diene-1-carboxylic acid (22.83; 15.05; 23.64%) and 4-(2-hydroxy-2-propanyl)cyclohex-1,3-diene-1-carboxylic acid (29.27; 18.35; 22.37%). These compounds were previously reported as a markers of linden honey found in its SPE extracts [19]. Interestingly, the percentage of these compounds was higher in the boiled meads than in the not boiled ones. This could be related to the hydrolysis of glycosidic precursors of these compounds that were also found in linden honey during cooking [20]. In DHLLE extracts of honeybee honey and mead, 4-hydroxybenzeneacetic acid (\(p\)-hydroxyphenylacetic acid) (6.40; 0.84; 6.94%), homovanmillic acid (0.36; 0.35; 4.89%) and _trans_-coniferyl alcohol (0.47; 1.68; 3.46%) were found. According to [PERSON] et al., 4-hydroxybenzeneacetic and homovanmillic acids are characteristic of honeybee honey [21]. \(p\)-Hydroxyphenylacetic acid and coniferyl alcohol were previously found in fir honeydew honey and the latter was proposed as its potential marker [22]. In comparison with the meads, the fermented glucose-fructose syrup did not contain any of the characteristic compounds that could be attributed to one of the analyzed honey types and were characterized by quite poor volatile profiles. The headspace of such fermented products (not boiled and boiled, respectively) was dominated by 2-phenylethanol (50.93; 31.98%), 2-methylpropan-1-ol (8.83; 20.65%) and 3-methylbutanal (17.32; 20.65%) that appeared after fermentation. The DHLLE extract contained characteristic products of the yeast fermentation (not boiled and boiled, respectively): 2-phenylethanol (25.32; 8.07%) and tryptophan (2.79; 1.38%), but also relevant amounts of aliphatic alcohols that were already present in the glucose-fructose syrup, not boiled and boiled fermented syrup, respectively): hexadecan-1-ol (3.40; 0.28; 3.33%), (\(Z\))-octadec-9-en-1-ol (30.46; 18.90; 30.42%), octadecan-1-ol (13.97; 12.74; 13.09%). Moreover, the extracts contained remarkable percentages of phthalates and tributuly acetylcholine, probably originating from contact with plastic packaging.