## 3 Significance of Volatile Organic Compounds in Honey
### Determination of Floral and Geographical Origin of Honey
Clearly, compounds that could be employed in the discrimination between honey's floral origins must be focused on plant-derived compounds and their metabolites, for instance terpen and its derivatives, benzene and its derivatives and norisoprenoids [4]. These compounds are characteristic of a given floral origin; as they are found only in certain types of honeys thus are considered as \"floral markers\" [39]. In other circumstances, the floral origin is determined by a greater concentration of certain compounds in some types of honey than in others or by the absence of determined compounds [14,40]. Some VOCs that have been considered as floral markers for specific honey types are shown in Table 1.  
On the other hand, difficulty is encountered in finding VOCs exclusively present in some honeys obtained from a specific botanical origin; this therefore justifies the use of sensory analysis to make this differentiation possible. Sensory evaluation is one of the most useful tools employed in honey characterization since it gives complete information about honey quality [3]. The combined study of chemical and sensory variables in the characterization of monofloral honeys may improve differentiations of honey types, and also provide some insights of the consumer preferences based on honey aroma [40]. In view of that, [PERSON] and [PERSON] [41] employed volatile composition together with sensory profile for estimation of authenticity of thyme honey. Knowledge about the floral origin of a honey will help to prevent fraud, standardize its quality and authenticate the honey thus allowing it to be competitive in the market [3]. Furthermore, the geographical origin of honey is a relevant factor that can influence its volatile composition. The accumulation of phytochemicals (carbohydrates, phenolic compounds and VOCs) is dependent on climatic conditions (sunlight, moisture), soil characteristics and other factors; therefore, it is reasonable to believe that differences between honeys obtained from different countries are bound to be due to the different compositions of pollen or nectar, which have the greatest influence on the chemical composition [42]. For example, the climatic conditions of Spanish chestnut forests, spread over different regions (north-east, north-west and south-east), influence the chestnut honeys volatile composition since they possess characteristic aroma profiles intimately related with the geographical area of origin [3]. \begin{table}
\begin{tabular}{|c|c|c|c|} \hline
**Method Employed** & **Honey Type/Country** & **Floral Marker** & **Reference** \\ \hline USE-GC-MS & Thyme (Greece) & \begin{tabular}{c} 3-hydroxy-4-phenyl-2- \\ butanone and 3-hydroxy-1- \\ phenyl-2-butanone \\ \end{tabular} & \begin{tabular}{c} [PERSON] \\ _et al_. [43] \\ \end{tabular} \\ \hline SDE-GC-MS & \begin{tabular}{c} Oak honeydew \\ (Spain) \\ \end{tabular} & Trans-Oak lactone & \begin{tabular}{c} [PERSON] \\ _et al_. [4] \\ \end{tabular} \\ \hline HS-SPME-GC-MS & \begin{tabular}{c} _Tolpis virgata_ \\ \end{tabular} & \begin{tabular}{c} 3,5-dihydroxytoluene and \\ tridecane \\ 1,3-diphenyl-2-propanane, \\ (3-methylbutyl)benzene, 3, 4, \\ 5-trimethoxybenzaldehyde and \\ 3, 4-dimethoxybenzaldehyde \\ \end{tabular} & \begin{tabular}{c} [PERSON] _et al_. [44] \\ \end{tabular} \\ \hline HS-SPME-GC-MS & \begin{tabular}{c} _Thymalae hirsuta_ \\ (Palestine) \\ \end{tabular} & \begin{tabular}{c} Benzene propanol, \\ benzylalcohol, nonanal, \\ hexanol and 4-methoxyphenyl \\ \end{tabular} \\ \hline HS-SPME-GC-MS- & \begin{tabular}{c} Acacia \\ Buckwheat \\ \end{tabular} & \begin{tabular}{c} Hexanal \\ Pentanal, furfural and \\ 2-ethylhexanol \\ \end{tabular} \\ HS-SPME-GC-MS- & \begin{tabular}{c} Lime \\ Olfactory \\ \end{tabular} & \
\begin{tabular}{c} \(p\)-methyl acetophenone \\ Methyl butanal and lilac \\ Idehyde \\ \end{tabular} &
\begin{tabular}{c} [PERSON] \\ _et al_. [32] \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 1: Specific floral markers used to determine the botanical origin of particular honey types. _Int.