# Screening Wild Yeast Isolated from Cocoa Bean Fermentation Using Volatile Compounds Profile
## 2 Results and Discussion
### Identification and Quantification for Volatile Compounds (VC's)
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Families** & \multicolumn{3}{c}{**Concentration [mg/kg]**} & **OTV * [mg/kg]** \\ \cline{3-5}
**Compounds** & **Compound** & **Min** & **Max** & \\ \hline  & 3-methylbutanal & 0.0069 & 18.6677 & 0.001 \\  & phenylacetaldehyde & 0.0054 & 54.0838 & 0.004 \\ aldehydes & 2-phenyl-2-butanal & 0.0107 & 0.1917 & 1.7 \\  & 4-methyl-2-phenyl-2-pentenal & 0.0007 & 2.9953 & - \\  & 5-methyl-2-phenylethyl-2-hexenal & 0.0029 & 3.0785 & - \\ \hline  & 3-hydroxai-2-butanone & 0.0013 & 0.0603 & 150 \\  & 2-heptanone & 0.0125 & 1.6152 & 0.14 \\ ketones & 2-octanone & 0.0077 & 0.0254 & 0.05 \\  & 2-nonanone & 0.0158 & 0.1291 & 0.2 \\  & 6-methyl-3.5-dihydro-2,3-dihydro-4h-pyran-4-one & 0.0001 & 0.3478 & 0.25 \\ \hline  & acetic acid & 0.0079 & 76.8848 & 33 \\  & 2 methyl propanoic acid & 0.0027 & 0.0861 & 2.3 \\ acids & 3-methylbutanoic acid & 0.0009 & 13.0664 & 0.022 \\  & 2-methylbutanoic Acid & 0.0125 & 0.6547 & 0.05 \\  & decanoic acid & 0.4681 & 3.0440 & 10 \\  & dodecanoic acid & 0.0447 & 0.3476 & - \\ \hline pyrazines & 2-methylpyrazine & 6.4451 & 6.4451 & 2.5 \\  & 2,3,5-trimethylpyrazine & 0.0178 & 0.2596 & 1.8 \\ \hline  & \multicolumn{3}{c}{* Taken by the authors from: Odor activity values ([PERSON] et al., 2003 [30]; [PERSON] et al., 2019 [31]; [PERSON], [PERSON], [PERSON], and [PERSON], 2013 [32]; [PERSON], [PERSON], [PERSON], and [PERSON], 2004 [33]; [PERSON] et al., 2018 [34]; [PERSON] and [PERSON], 2008 [22]; [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON], 2007 yang [35]; [PERSON], [PERSON], and [PERSON], 2017 [36]; [PERSON] et al., 2017 [37]; [PERSON] and [PERSON], 2005 [38]).} \\ \hline  & & & & \\ \end{tabular}
\end{table} 
Table 1: _Cont._Although ethanol's concentration was the highest while 3-hydroxi-2-butanone concentration was the lowest, these results are insufficient to assure that those compounds' concentrations reach the levels to be sensed olfactorily; therefore, is very important to analyze this sense. For example, ethanol has an olfactory threshold value (OTV) greater than 3-methyl butyl acetate and 2-phenyl ethyl acetate; which emphasizes that these last compounds are 80 and 17 times easier to perceive than ethanol, respectively. The 3-methyl butanal was the compound identified and quantified with the lowest OTV (0.001 mg/kg), which re der this compound approximately 766 times more perceptible than ethanol. This means that, although the concentration of 3-methyl butanal was 52 times lower than of ethanol, in a one-to-one comparison, the characteristic odor of 3-methyl butanal (flowers) will be more perceptible than ethanol. Therefore, the concentrations of compounds are insufficient to perform an equilibrate comparison between different families of compounds responsible for aroma and flavor. This work stands out for being the first study in which the volatile compounds produced by wild yeasts from Colombian cocoa fermentation boxes are identified and quantified. Additionally, the ability of wild yeasts to produce certain volatile compounds associated with desired aromas in cocoa beans, such as 3-methyl-1-butanol (floral), 3-methyl butyl acetate (banana), acetate of 2-phenyl ethyl (honey or strawberries), phenylacetaldehyde (walnut), among others; compared with other studies such as [PERSON]'s that used commercial yeasts ([PERSON] et al., 2016). In addition, it is observed that the compounds mentioned in the previous paragraph exceed the detection threshold (OTV), therefore, it is very possible that in a directed fermentation, cocoa beans are obtained with the perceptions previously described and complemented in the supplementary material (Table S1). Although an individual analysis of each yeast and each compound can be done, such an analysis would be extensive due to the large number of analysis possibilities that could be presented. For this reason, in this work, it was decided to propose an approach based on PCA (which includes filters) and cluster analysis to prioritize those yeasts with the greatest potential to produce volatile compounds.