## 4 Discussion
However, a quantification of isomeric groups of wax esters [25] and fatty acids [16] has recently been reported, since their relative ionization response depends only on lipid family and saturation degree and is not affected by carbon chain length. A similar approach was employed here, as shown in Figure 5, wherein the lipids' molecular formulas were extrapolated from the mass list obtained through ESI (\(-\)) MS analyses of the organic extract. Then, they were summarized in two main families based on their saturation degree and carbon chain length to obtain their relative extent. Notably, in the C18 series (18:0-18:3) shown in Figure 6, linoleic acid (18:2) is the most abundant species (ca. 50%), followed by oleic (18:1) and stearic (18:0) acids, ca. 27% and 17%, respectively, whereas linoleic (18:3) acid amounts to ca. 6%. Figure 7 displays the relative abundance of EFAs (essential fatty acids), with linoleic acid (\(\omega\)-6) found to be ca. ninefold more abundant than linolenic (\(\omega\)-3) acid. _Terpenes_: It has been demonstrated that insects can be a source of terpen through both specific biosynthetic pathways that occur in insects and the accumulation of these molecules from plants [26]. In a previous study, [12] two terpenes, \(p\)-cymene and \(\beta\)-myrcene, were identified in _A. domesticus_ powder by means of an in-tube extraction technique (ITEX) coupled with GC-MS. Here, a further characterization of house crickets' terpene profile was carried out by means of SPME-GC-MS. Specifically, together with the previously identified \(\beta\)-myrcene and \(p\)-cymene, \(\gamma\)-terpinene, \(\alpha\)-thujene, \(\beta\)-thujene, and 4-carene were detected for the first time. Among them, \(\gamma\)-terpinene (16.8%) and \(p\)-cymene (17.2%) were the most abundant terpenes, whereas the other metabolites were present with percentage mean values ranging from 0.7% to 3.5%. Since terpen are a class of compounds characterized by  
Figure 5: Histograms of relative distribution (mean value of the three analyzed batches \(\pm\) SD) of specific classes of saturated fatty acids (SFA) obtained through ESI (\(-\)) MS analyses of organic _Acheta domesticus_ powder extracts. Figure 6: Histograms of relative distribution (mean value of the three analyzed batches \(\pm\) SD) of specific classes of C18 series fatty acids obtained through ESI (\(-\)) MS analyses of organic _Acheta domesticus_ powder extracts. several biological activities, it will be interesting to correlate the presence of these molecules with the potential influence of cricket extracts on human health. _Alkanes_: The GC-MS analysis of hexane extracts allowed us to identify lipophilic compounds present in spray-dried _A. domesticus_ powder, namely hexadecenoic acid and alkanes. It is noteworthy that a previous GC-MS study on _A. domesticus_ PLE (pressurized liquid extraction) extract already detected a series of lipophilic compounds indicated to be \"alkane\", without identifying their precise structure [10]. Here, for the first time, the elucidation of the alkane compounds present in house crickets was carried out. Specifically, thirteen alkanes were identified, namely octane, decane, and eleven methyl-branched hydrocarbons (MBCHs). MBCHs are a particular class of compounds naturally produced by insects for their inter- and intraspecific communication [27]. Among them, methylcyclopentane was the main compound present in a percentage (62.9%) at least 100 times higher than the other detected molecules. The relevant presence of methylcyclopentane has also been reported in other insects, namely Azteca ants and _A. dichtoma_[28; 29]. The presence of this compound in a new food matrix such as in crickets or other edible insects will be the object of interesting research regarding the potential biological activity of these molecules, since the reported presence of this chemical class in other food sources is limited to a few studies regarding the cuticular composition of crustaceans [30].