# Volatile Composition of Industrially Fermented Table Olives from Greece
## 3 Results and Discussion
### Effect of Geographical Origin on Volatile Profile  
After these encouraging results, the samples from each cultivar were grouped according to their growing location (Table 1), and PCA was conducted to reveal any discriminating variables (volatiles). The CNS table olives were produced in Magnesia (MAG), Fthiotida (FTH) and northern Evia (EVIA). These neighboring regions are in central-eastern Greece (Figure S1). As shown in Figure 3a, three distinct clusters are evident in the plot of the two first PCs, which both accounted for 86% of the total variance. The MAG cluster is placed on the negative side of PC1 due to its high content of butyl butanoate (78), methyl butanoate (58), ethyl butanoate (62), 3-methylbutyl butanoate (81), butanoic acid (5), butanol (18), guaiacol (113) phenol (115), acetoin (46) as well as the phenols class (Figure 3b). The other two clusters (FTH, EVIA) are both on the positive side of PC1, which seems reasonable due to the high proximity of these geographical regions (Figure S1). The volatile compounds mainly associated with the FTH cluster were the esters class as well as the individual esters benzyl acetate (96), benzyl propanoate (98), ethyl 2-hydroxybenzoate (99), methyl benzoate (95), ethyl 3-hexenoate (83), (Z)-3-hexenyl acetate (84), 1-methylpropyl propanoate (64) and ethyl hexanoate (80). On the other hand, EVIA samples were related mostly with ethanol (12), 2-butanol (13), propanol (14), (Z)-2-hexen-1-ol (30), (E)-2-hepten-1-ol (34), ethyl 2-methylbutanoate (65), ethyl 3-methyl-2-butenoate (79), methyl lactate (85), ethyl lactate (89) and isopropyl lactate (92). Similar results were observed on the heatmap (Figure S4) of the hierarchical cluster analysis. Furthermore, it is evident that PC2 incorporated the discriminating variation between the FTH and EVIA clusters because they were placed in opposite quadrants along the y-axis. This differentiation can be attributed mostly to the higher content of (E)-2-hexenol (29) and 3-methylbutyl acetate (70) in EVIA and FTH samples, respectively (Figure 3b). HLK table olives were produced in Halkidiki (HAL) and Kavala (KAV) (Figure S1) using the Spanish-style method. It is evident from the PCA scores plot (Figure 4a) that the KAV samples clustered in the negative side of PC1, whereas HAL samples were on the positive side of PC1. Thus, PC1 compensates all the information (78% of explained variance) that differentiates HLK table olives according to growing location. PC2 and PC3 explain the variance within each cluster (Figure 4a, Figure S5). The examination of loading plot (Figure 4b) revealed that the KAV samples were characterized mainly by a higher content of volatile phenols (including the sum of phenols' class), such as guaiacol (113), phenol (115) and 4-methylphenol (118). In addition, they were richer in propanoate esters, such as 1-methylpropyl (64), methyl (54), benzyl (98), 2-phenylethylly (101), propyl (63) and butyl (73) propanoate, which are correlated with the increased amount of propanoic acid (3) (Table 2). On the other hand, the HAL samples were mainly associated with acetate esters (ethyl (53), isobutyl (60), 3-methylbutyl (70), pentyl (74), hexyl (82) and (Z)-3-hexenyl (84) acetate), ethyl esters (ethyl octanoate (93), lactate (89), 3-hexenoate (83), hexanoate (80), pentanoate (72), 3-methylbutanoate (67), butanoate (62) and 2-methylpropanoate (56)) and methyl esters (methyl octanoate (91), lactate (85) and hexanoate (75)). The higher content of esters correlated positively to those of alcohols (ethanol (12), 2-methyl-1-propanol (15), 2- and 3-methyl-1-butanol (20, 21), 1-hexanol (26), (Z)-3-hexenol (27), 2,3-butanediol (35) and acids (acetic (1), hexanoic (9) and octanoic (10) acid). The differentiation of HLK tables olives according to geographical origin has been also confirmed by hierarchical cluster analysis (Figure S6). Figure 3: Principal component analysis of the volatile compounds identified in cv.