## 3 Results and Discussion
### Planning and Selection of Volatile Markers Suitable for Formulations
This explains why the maximum content (relative area 1119.060) was found in an oil without this sensory defect (its defect was fusty-muddy). This compound was considered as an outlier to calculate the median in Table 2, although the high content of ethanol can be easily found in VOOs with fermentative defects. The content of ethyl acetate was also higher in VOOs with winey-vinegary defect. In fact, the maximum content (relative area 3.149) was found in a sample with this sensory defect. The relative areas of these compounds in a RM of winey-vinegary defect provided by the IOC revealed a high content of acetic acid and ethyl acetate (even four and six times, respectively, the maximum content found in the 63 VOOs). On the contrary, a low content of ethanol was found, even lower than some relative areas found in EVs. Regarding the two volatile compounds selected for rancid defect, hexanal showed a higher mean of relative area in rancid oils. However, the maximum content was found in VOOs with no rancidity and the minimum content was found in VOOs with rancid defect. This observation is explained by the dual contribution of this compound to green fruitiness aroma, on one hand, originating from \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Volatile Compound** & **Category** & **N** & **Mean (Min–Max)** & **RM IOC** \\ \hline \multirow{3}{*}{Acetic acid} & EV & 12 & 0.212 (0.037–1.115) & \\  & V-L (excluding those with winey-vinegary defect) & 44 & 0.678 (0.045–8.485) & 8.688 \\  & V-L (winey-vinegary as main defect) & 7 & 1.506 (0.436–2.389) & \\ \hline \multirow{3}{*}{Ethanol} & EV & 12 & 0.423 (0.111–1.030) & \\  & V-L (excluding those with winey-vinegary defect) & 44 & 2.770 (0.083–53.688) a & 0.581 \\  & V-L (winey-vinegary as main defect) & 7 & 4.381 (0.033–19.039) & \\ \hline \multirow{3}{*}{Ethyl acetate} & EV & 12 & 0.150 (0.021–0.530) & \\  & V-L (excluding those with winey-vinegary defect) & 44 & 0.345 (0.013–1.519) & 19.620 \\  & V-L (winey-vinegary as main defect) & 7 & 0.874 (0.236–3.149) & \\ \hline \multirow{3}{*}{Hexanal} & EV & 12 & 0.731 (0.116–1.497) & \\  & V-L (excluding those with rancid defect) & 31 & 0.680 (0.069–6.533) & 8.396 \\  & V-L (rancid as main defect) & 20 & 1.013 (0.065–3.064) b & \\ \hline \multirow{3}{*}{Nonanal} & EV & 12 & 0.002 (tr–0.004) c & \\  & V-L (excluding those with rancid defect) & 31 & 0.003 (0.001–0.009) & 0.074 \\ \cline{1-1}  & V-L (rancid as main defect) & 20 & 0.009 (0.001–0.050) & \\ \hline \hline \end{tabular}  
* With outlier 28.140 (0.083–119.060). b With outlier 9.178 (0.065–164.316). c tr, traces.  
\end{table} 
Table 2: Relative areas of volatile compounds selected to emulate winey-vinegary and rancid defects in VOOs in a set of 63 samples and in RMs provided by the IOC for each of the defects (RM IOC). the lipoxygenase pathway, and rancidity, on the other hand, when it reaches a high concentration as a consequence of lipid oxidation [39]. Nonanal showed the highest relative areas in VOOs with rancidity, and its maximum in these oils was 10 times higher than the maximum in the VOOs without this sensory defect. The RM of rancid oil provided by the IOC showed relative areas of hexanal and nonanal near the maximum found in VOOs (1.33 and 1.45 times the relative area of the maximum found in the 63 VOOs, respectively). The flow diagram shown in Figure 2 starts with the preparation of a first formulation with the selected volatile markers (Table 2) to emulate a particular sensory defect (rancid or vinegar) with the aim of carrying out an iterative process to optimize composition and concentrations. This phase, described in the following two sections for winey-vinegary and rancid defects, was called the \"building process\" (Figure 2). In this phase, the first formulation was submitted to the experimental design of modified simplex [29]. In each iterative step of the modified simplex, a set of trained assessors determined three described desirability properties (see Section 2.4): representativeness, odor persistence, and formulation simplicity.