# Volatile Composition of Industrially Fermented Table Olives from Greece
## 3 Results and Discussion
### Volatile Composition of Table Olives
However, the most prevalent differences were observed in the minor chemical classes. More specifically, the phenol content ranged from 1.1% to 11.9% for KLM and HLK samples, respectively. An opposite trend was observed for terpenoids (KLM: 5.2%, HLK: 0.17%). On the contrary, CNS samples were characterized by the highest content (\(p<0.05\)) of hydrocarbons (3.2%) and miscellaneous compounds (2.5%). The sum of carbonyl compounds did not differ significantly between the cultivars. In accordance with our results, [PERSON] et al. [31] reported that CNS olives contained higher concentrations of esters than KLM olives. In addition, they found that alcohols were the second most abundant chemical class in CNS samples, whereas in KLM samples the alcohol content varied significantly during fermentation. In a study conducted with Spanish-style green table olives originated from three Spanish cultivars (Manzanilla, Gordal, Hojbilanca), the volatile profile was predominated by alcohols and phenols, followed by esters and acids. It is noteworthy, that the phenol content was quite high in the Spanish cultivars (\(\sim\)30-35%), whereas in our case (HLK samples), phenols represented \(\sim\)12% of total volatiles. This could be attributed mainly to the different levels of phenolic substrates due to cultivar species or/and the degree of olive ripeness, as it will be explained later. As presented in Figure 1, the growing location of table olives had a significant effect on the various chemical classes within each cultivar, except for KLM. The relative amount of phenols, terpenoids and acids was higher in HLK samples produced in Kavala (KAV), whereas alcohol content was higher in samples produced in Halkidiki (HAL). Within the CNS samples, all chemical classes varied significantly between the three growing locations, namely Fthiotida (FTH), northern Evia (EVIA) and Magnesia (MAG). The latter samples contained greater amounts of phenols, acids, terpenoids, hydrocarbons, carbonyls and miscellaneous compounds (\(p<0.05\)). On the other hand, esters and alcohols were significantly higher in FTH and EVIA samples, respectively. A closer observation of the relative content of the principal volatile compounds (Table 2) can reveal several key differences for the effect of cultivar/processing method and growing location of table olives. Of the 11 volatile acids identified in our study, acetic acid was the dominant one followed by propanoic acid in most cases, such as HAL, FTH, EVIA, AIT and PEL samples (representing 8.7-18.1% of total volatiles). However, the dominant acids in KAV and MAG samples were propanoic acid (17.8%) and butanoic acid (19.3%), respectively. It is generally known that acetic acid is produced by bacteria such as _Acetobacter_ species, _Clostridium acetobutylcium_ as well as yeasts by oxidation of ethanol [13]. The formation and content of propanoic acid depends on the growth of _Propionibacterium_ species [7]. Although increased levels of butanoic acid resulting from the action of _Clostridium_ or _Ruminococcus_ species [29] can lead to butyric spoilage, no such malodorous deterioration was observed during the organoleptic evaluation of our samples (data not shown). Of the 30 identified alcohols, ethanol, 2-butanol, 3- and 2-methyl-1-butanol, phenylethyl alcohol and 1-propanol were found in appreciable amounts in the samples from the three cultivars (Table 2). The highest content of ethanol (\(\sim\)20%) was observed in KLM samples  
Figure 1: Comparison of the relative content (%) of chemical classes of the volatile compounds identified in industrially fermented table olives originating from various (**a**) growing locations (HAL: Halkidiki; KAV: Kavala; FTH: Fthiotida; EVIA: northern Evia; MAG: Magnesia; AIT: Aitoloakarmania; PEL: Southern Peloponnese) and (**b**) cultivars (HLK: Halkidiki; KLM: Kalamata; CNS: Conservolea). The error bars indicate standard errors at 95% confidence level. (AIT, PEL), followed by 2-butanol and 3-methyl-1-butanol.