## 3 Results and Discussion
### Chemical Composition of Extracts Volatile Fraction
Canfora and _cis_-geraniol were also present in smaller amounts; however, they have been reported to contribute to biological and antioxidant activity [37; 42]. In literature, there are few studies of the chemical composition of extracts from coriander fruits; the terpen profile found is similar to coriander seeds essential oils previously reported by [PERSON] et al. [43] and found in literature [44; 45; 46]. For each matrix, the SPME/GC-MS identified compounds were associated with four main classes of terpen (class assignment of each compound is in Table 2). To explore potential correlations among the whole data set the PCA algorithm was used. Figure 1 reports the PCA biplot obtained for the different terpen classes (loadings), determined in extracts of thyme, hemp, and coriander (scores). The total variance explained was 70.51%, with the first component accounting for 42.94% and the second for 27.57%. From the biplot, it is evident that thyme extract obtained from Soxhlet at 2 h of extraction (T S2h) is separated from all extracts based on the major content of monocyclic and bicyclic monoterpenes. These two classes of terpen are strongly correlated. Sesquiterpenes were the most abundant compounds in hemp 6 h RSLDE extract (H N6h), while acyclic monoterpenes represented mainly the volatile fractions of coriander ultrasounds-assisted (C UAE) and 6 h RSLDE (C N6h) extracts. Based on the studied variables, from PCA is also evident the presence of different clusters; in particular, on PC1 the extracts C M, T N6h, T 56h, and T N2h are well grouped (positive correlation with PC1). The same applies for C 56h, C 52h, C N2h, H 52h, and H 56h (negative correlation with PC1). To evaluate the influence of the extraction techniques on each matrix, the dataset was also processed through cluster analysis. Cluster analysis is a valid tool of multivariate analysis that has been already used and is useful to underline the differences among extraction techniques and conditions for the isolation of compounds from plant matrices [47; 48]. Clusters were formed to contain four components (acyclic monoterpenes, monocyclic monoterpenes, bicyclic monoterpenes, sesquiterpenes). Figure 1: Biplot (scores and loadings) obtained from the PCA on data set of different extracts (rows) and terpen classes analyzed (columns). In the Figure: T, thyme; H, hemp; C, coriander seeds; N2h, RSLDE 2 h; N6h, RSLDE 6 h; S2h, Soxhlet 2 h; 56h, Soxhlet 6 h; UAE, ultrasound assisted extraction; M, maceration. The dendrograms obtained from a cluster analysis of coriander, hemp, and thyme data are illustrated in Figures 2-4, respectively. From the coriander dendrogram (Figure 2) is evident that the diagram is divided into three classes: one class comprising only M extract, and the other 2 constituted by N2h and Soxhlet at 2 and 6 h (S2h and S6h) extracts, and N6h and UAE extracts, respectively. A similar classification was achieved for hemp (Figure 3). In both dendrograms, the N6h/UAE class has large distance from the M class, meaning that these extraction techniques allowed for the isolation of different classes of terpenes. Indeed, N2h and Soxhlet at both 2 and 6 h of distillation time, have similar extraction patterns. For thyme (Figure 4), a different distribution is obtained; one class consists of M, N2h, S6h, and UAE, the second and third consisting of only N6h and S2h, respectively. In this case  
The cluster analyses of terpenes allowed to underline that there were not clear patterns of extraction that can help in selecting a particular technique for the extraction of a certain class of terpenes. This is mainly related to the variables that occur before, during and after the extraction process and that influence the outcomes [8]. Anyhow, for all matrices the RSLDE at 2 h of extraction is always clustered with Soxhlet at 6 hours, indicating that, regardless of matrix nature, the extraction patterns are very similar for the two approaches.