# The Infestation of Olive Fruits by _Bactrocera oleae_ ([PERSON])
## 2 Results and Discussion
### Effect of B. oleae Infestation on the Volatile Profile of VOO
Although there were no significant differences in terms of total content of C5/LnA compounds, a very significant decrease was observed in the content of carbonyls C5/LnA, which is mainly due to a strong decrease in the content of pent-1-en-3-one. Unlike the pentene dimers, which are the most abundant components of this group of compounds but have no impact on the aroma of the oil [26], pent-1-en-3-one has been described as an undesirable contributor to VOO aroma, providing green-pungent odor notes [13]. The content of this compound measured in oils from fruits attacked by the olive fruit fly is clearly lower than in control oils, 70, 35, and 50% in cvs. Picul, Manzanilla, and Hoijblanca, respectively. These data are also similar to those reported for _V. dahliae_ infection in which the average content of this compound was 50% lower in oils from _V. dahliae_ inoculated olives. Similarly, to what is found in oils from _V. dahliae_-infected olives, the content of LOX esters, the main contributors to oil fruitiness [26], was also significantly increased in the oils from _B. oleae_-infested fruits (Figure 1 and Table S2). To date, there are very few studies on the modification of the aroma of VOO due to _B. oleae_ infestation, and those that exist have reported contradictory results, most likely because the oils were obtained from cultivars with different stages of maturation, cultivation areas, and extraction technologies [28; 29]. In our study, these variables were fixed; thus, the three olive cvs. Picul, Manzanilla, and Hoijblanca were grown, harvested, and processed under identical conditions, showing a very similar response pattern to _B. oleae_ infection in terms of green volatiles formed through the LOX pathway. Recently, compounds with a different biochemical origin such as toluene, \(\beta\)-myrcene, limonene, and \(\beta\)-ocimene have been also linked to the infestation status of olive fruits attacked by _B. oleae_[30; 31]. In this sense, we have also found significant increases in the content of ethanol, ethyl acetate, and \(\beta\)-ocimene in oils from _B. oleae_-infested fruits. Although ethanol and ethyl acetate are volatile components that appear in trace amounts in most oils [32], in our study, we have found significantly higher amounts of both compounds in the oils from infested fruits (Table S2). These increases would be related to fermentative processes triggered in the wounds caused by the fly. Ethanol and ethyl acetate are major contributors to the 'fusty' oil organoleptic defect, which is the most frequently identified by sensory evaluation in oils obtained from _B. oleae_-infested olive fruits [33]. Especially striking were the increases observed in the content of \(\beta\)-ocimene, a minor terpene compound, whose content significantly increased due to infestation, especially in oils from Picul and Manzanilla cultivars, where its concentration increased five and four times, respectively. According to [PERSON] et al. [31], \(\beta\)-ocimene is the volatile compound most positively correlated with the infestation of olive fruits by _B. oleae_. Accordingly, a high-moderate correlation (\(r=0.626\)) was found for \(\beta\)-ocimene content in VOO and _B. oleae_ infestation (Table S3). However, higher significant (\(p\leq 0.05\)) positive and negative correlations were found for other volatile compounds and _B. oleae_ infestation (Tables S2 and S3). Thus, the highest positive correlation coefficients were found for ethyl acetate (\(r=0.822\)), (_E_)-hex-2-eral (\(r=0.753\)), and (_E_)-hex-2-en-1-yl acetate (\(r=0.764\)), while the most negative correlations were found for (_Z_)-hex-3-enal (\(r=-0.910\)), pent-1-en-3-one (\(r=-0.902\)), and (_Z_)-pent-2-enal (\(r=-0.927\)). PC analysis was applied using as variables the content of those volatile compounds with significant correlation coefficients (Figure 2). The first and second principal components described 80% of the total variability (PC1 60.58% and PC2 20.73%).