## 3 Results and Discussion
### Building a Formulation as RM for the Winey-Vinegary Defect
In order to optimize the concentrations of the volatile compounds that are responsible for fruity perceptions (green, fruity) to build a proper \"green base aroma\", the four compounds--1-hexanol, _E_-3-hexen-1-ol, hexanal, _E_-2-hexenal--were diluted together at two different concentrations for each compound: 50 mg/kg and 35 mg/kg. The formulation at 50 mg/kg was qualified by all assessors as \"a neat green with a bit almond\". However, two assessors reported \"rancid\" sensory notes that are characteristic of hexanal and _E_-2-hexenal at high concentrations. However, a decrease of 30% in the concentration of these volatiles (35 mg/kg) widely modified the sensory perception of the formulation by assessors who qualified it as \"green with a bit almond perception\". The assessors reported that they recognized the characteristic aroma of _E_-2-hexenal (green almond), which seems to have be prevalent over the other aromas (more green or green apple). No rancid notes were detected. However, in terms of representativeness, the aroma of the formulation at 50 mg/kg was considered more natural and closer to VOO than the formulation at 35 mg/kg. Consequently, the concentration of 50 mg/kg was selected as the starting concentration for providing the \"green base aroma\". A mixture of the \"green base aroma\" together with the three primary compounds at high concentration (acetic acid and ethanol diluted at 600 mg/kg and ethyl acetate at 200 mg/kg) was prepared, coded as AV2 (Table 3), and submitted to the modified simplex procedure [41]. The modified simplex produced a series of formulations (Table 3) with concentrations of the \"primary volatile compounds\" that were responsible for detection in the high range (>600 mg/kg) mixed with several levels of concentrations of the four volatiles responsible for the green perception at the low concentration range (<50 mg/kg). The formulations coded as AV2-AV5 were rejected by assessors as having low representativeness of the aroma presenting sensory notes that were not related with winey-vinegary defect. Moreover, some glue, rancid, and wood notes were detected. Furthermore, the winey-vinegary notes were detected at low intensity and this aroma was identified as \"non-natural\". The required characteristic of odor persistence was not satisfied due to the low intensity of the aroma. These four formulations were composed of diverse concentrations of the three primary volatile compounds: AV2 and AV4 were prepared with ethyl acetate at medium concentration (200 mg/kg) and ethanol and acetic acid at low concentration (600 mg/kg). The formulation AV3 was made with higher concentrations of ethyl acetate (400 mg/kg) and ethanol and acetic acid (1200 mg/kg). Finally, the formulation AV5 was prepared with much lower concentration of ethyl acetate (40 mg/kg), which was identified as a compound that produced a non-natural aroma. In this formulation, ethanol was added at very high concentration (5000 mg/kg) since this compound was identified as an enhancer of the vinegary perception produced by acetic acid, whose concentration was kept low (600 mg/kg). The concentration of the set of volatiles responsible for green perception was also reduced to avoid the rancid perception reported by some assessors and to avoid masking the winey-vinegary defect, which was considered as non-evident by assessors in these formulations. In the evaluation of these four formulations (and in others not shown in Table 3), some conclusions were extracted. First, the sensory evaluation of these formulations did not result in a unanimous