## 3 Results and Discussions
### Volatile Profile of the Mastic Gum Samples
#### 3.2.5. Other Compounds  
Sesquiterpene oxide, dilepton, volatile phenol, volatile acid, ketone, and aldehyde compounds were detected in both MGT and MGG samples in addition to the monoterpenes, monoterpenoids, sesquiterpenenes, and alcohols in the present study (Table 2). However, unlike the MGG sample, the MGT sample contained one ester compound (linaly acetate). A previous study reported this constituent in lower-quality mastic oil, while high-quality oil had it only in trace amounts [16]. It was observed in the current study that caryophyllene oxide (a sesquiterpene oxide) and geranyl linalo (a diterpenoid) were present at higher concentrations in the MGG sample (Table 2). Caryophyllene oxide has also been identified in mastic gum and its essential oil in prior studies [10; 12; 28]. In addition, two volatile phenols, 2-methylanisole and methyl isoeugenol, were identified in the MGG sample, whereas only 2-methylanisole was detected in the MGT sample. Previous studies have similarly reported the presence of methyl isoeugenol in mastic essential oil [2; 16; 28; 30]. Furthermore, methylanisole was found in mastic gum essential oil obtained through both hydrodistillation and supercritical extraction [10]. Earlier studies similarly reported this compound in mastic oils from Greece [19; 27]. Acetic acid, a volatile acid, was present in both mastic gum samples in the present study, with a much higher concentration in the MGG sample (60.0 \(\upmu\)g/kg) compared to the MGT sample (4.5 \(\upmu\)g/kg). In a prior study, [PERSON] et al. [11] also reported acetic acid in mastic samples. Two ketones, sulcatone (6-methyl-5-hepten-2-one) and 2-undecanone, were identified in the MGG sample, while only sulcatone was detected in the MGT sample in the current study. Sulcatone was previously detected in trace amounts in the essential oils obtained from the _P. lentiscus_ L. and _P. lentiscus_ var. Chia grown in the Cesme district of Izmir province, Turkiye [18] while 2-undecanone was reported in mastic gum and its oil [27; 29]. It was found that both mastic gum samples contained the aldehydes isoneral and \(\alpha\)-campholenal in the present study. \(\alpha\)-campholenal was also previously identified in the _P. lentiscus_ var. Chia mastic oil [2; 10; 30]. Overall, these aroma groups, such as volatile phenols, volatile acids, ketones, and aldehydes, constituted a minor fraction of the mastic aroma. Geranyl linalool and isoneral were identified in mastic gum for the first time in this study.  
Consequently, it was observed in the present study that the geographical region plays a significant role in determining the composition and aroma profile of mastic gums. Environmental factors such as temperature, humidity, light, and soil properties strongly influencethe aroma properties of the mastic gums from different origins [34; 35]. In addition, after the harvest, physicochemical reactions such as oxidation, polymerization, and evaporation occur, altering the aroma profile of mastic gums. The environmental temperature, particularly during the formation of mastic gums on the tree trunk, can further accelerate these reactions, contributing to variations in its aroma composition [17; 19; 36].