# Profiling Croatian Whisky Using GC/MS-MS and UHPLC-QTOF
## 3 Results and Discussion
### Aromatic Profile of Croatian Whisky Determined by SPME-GC-MS
#### 3.3.7 Fatty Acids and Related Compounds  
The following compounds are less common in discussions of whisky flavor and may not be major contributors to its typical profile. For example, 9,10-Dihydroxyoctadecanoiic acid, potentially related to fatty acid oxidation products, lacks specific documentation on any flavor contribution. Phloionolic acid, may be related to phenolic compounds in general and might influence flavor through astringency and complexity, particularly from the oak aging process. Similarly, Z-5,8,11-trihydroxyoctadec-9-enoic acid could be related to fatty acid oxidation products or degradation of lipid-derived materials in the aging process. Long-chain dicarboxylic acids, like octadecanoiic acid, could be related to the breakdown of fatty acids from the oak wood or from the distillation process. It is not typically cited as contributing to flavor in whisky. Hexadecanoiic acid and 9-octadecenoic acid, both dicarboxylic acids, could potentially originate from the fatty acid metabolism within the wood of the barrel or from the distillate itself. They might add a subtle acidic or buttery profile to the whisky, contributing to the tactile sensation or mouthfeel [37]. Hydroxy acids like 9-hydroxy-10,12-octadecanoic acid (HODE) and 2-hydroxyhexadecanoic acid may contribute to the flavor profile of the whisky through slight acidity and potentially creamy or slightly greasy notes [37]. They are often associated with the oxidative degradation of linoleic acid and might be linked with aging processes in whisky. However, HODEs' direct contribution to flavor is not well-documented. Ricinoleic acid, a fatty acid found in castor oil, is known for its unique viscosity and solubility, which could influence the mouthfeel of whisky. However, scientific literature rarely mentions its presence or favor contribution in whisky. The monounsaturated dicarboxylic acid 9-octadecenoidoic acid (9Z-) could result from the oxidation of oleic acid. It is not commonly cited in whisky flavor discussions but may contribute to the texture or mouthfeel of the whisky. Gingerol, known for its warming and spicy characteristics found in ginger, could impart such notes in whisky. Although ginger itself is not typically used in whisky production, spicy notes akin to gingerol can originate from the wood or during fermentation and distillation [37]. However, this would be quite unusual unless ginger were specifically added during production, either intentionally or it could be present in whisky due to several potential sources, such as the raw ingredients used in distillation, chemical reactions during fermentation and aging, or extraction from the wood of the casks during maturation. The comparison with other research findings is thus challenging, as these compounds themselves are not standard markers looked for in whisky research and may not be significant to the typical sensory profile as compared to other better-studied congeners such as phenolic compounds derived from wood, esters formed during fermentation, or alcohols that contribute to the body and character of whisky [1]. Figures S1 and S2 (Supplementary Materials) highlight the presence of two unknown compounds with molecular masses of \(m/z\) 1006.12918 and 978.09907, respectively. These findings suggest unique chemical entities present in certain whisky samples. The high molecular masses indicate these compounds could be large polyphenic structures or other complex organic molecules possibly derived from the maturation process or specific ingredients used in whisky production. Further identification and characterization of these  
unknowns could provide insights into the distinct flavor profiles or aging processes that differentiate the whiskies. The PCA plot in Figure 3 offers a statistical evaluation of the whisky samples based on their chemical composition. By reducing the dimensionality of the dataset, PCA reveals groupings and separations among the whiskies, illustrating variability in their chemical profiles.