# Screening Wild Yeast Isolated from Cocoa Bean Fermentation Using Volatile Compounds Profile
## 2 Results and Discussion
### Identification and Quantification for Volatile Compounds (VC's)  
The results related to the identification of VCs for each wild yeast will be exemplified using the yeast Y111. Each compound was tentatively identified using the mass spectra library since standards or chromatographic retention indexes were not available. Figure 2 shows the chromatogram of yeast Y111, where major intense peaks A and B, elute at 14.601 and 37.568 min, respectively. The first peak (A) corresponds tentatively to 3-methyl butyl acetate and the second (B) is tentatively 2-phenylmethyl acetate. ; however, Figure 3 shows the mass spectrum for 3-methyl butyl acetate to illustrate the analysis developed. Figure 3a shows the spectrum of the sample while Figure 3b shows the spectrum of NIST SDR 169 libraries from 3-methyl butyl acetate, and a comparison of them figures confirms that both mass spectra coincide with a probability of certainty of 90%. In addition, the fragmentations patterns models of this compound include the following fragments: acetyl at \(m/z=43\), isobutyl at \(m/z=55\), isoamyl at \(m/z=70\) and ethyl acetate at \(m/z=87\), which suggests that signal of spectrum probably corresponded to a 3-methyl butyl acetate. Additionally, the identity of the compound was confirmed by comparison of their experimental Kovats Index (Klexp = 859) with reported in the literature for 3-methyl butyl acetate (KI = 867) (Table 1). The absolute relative error between Klexp and KI was 0.9%, therefore, this result confirms the identity of the compound. The results obtained for 3-methyl butyl acetate coincided with those found by [PERSON] et al. [21], who confirmed the structure and identity of this compound using the presence of the fragment peak at \(m/z=87\). This procedure was performed for all volatile compounds produced by each wild yeast, obtained a total of thirty-six compounds were tentatively identified and were grouped as follows: 12 esters, 6 alcohols, 6 acids, 5 aldehydes, 5 ketones, and 2 pyrazines (Table 1). For the family of alcohols, the most abundant compounds were ethanol, 3-methyl butanol, and 2-phenyl ethanol (2-PE). Ethanol was the compound that reached the highest concentration of all the volatile compounds evaluated with 974.85 mg/kg, this result is to be expected because ethanol is a primary metabolic product of the fermentation of sugars, which is directly related to the growth of yeasts present in the Sabouraud culture medium. In cocoa fermentation, the ethanol produced by yeasts is used as a carbon source for acetic acid bacteria and triggers biochemical reactions within the cocoa bean that lead to the production of aroma precursors [22]. Results presented in Table 1 show that yeasts were able to produce high concentrations of 2-phenyl ethanol (2-PE), about 51.4509 mg/kg, evidencing the potential of the strains for producing this important aromatic alcohol during the fermentation process. The ability to synthesize this compound naturally has been reported for different strains of yeasts, such as _Saccharomyces cerevisiae_, _Kluyveromyces marxianus_, _Kluyveromyces lactis_, _Pichia fermentans_, _Pichia anomala_, _Schizosaccharomyces pompe_, and _Hansenula anomala_. The compound 2-phenyl ethanol is produced by yeasts using two routes: converting L-phenylalanine (L-Phe) via the Ehrlich pathway or by de novo synthesis from sugars [23; 24; 25]. According to [PERSON] et al. 2020, alcohols and acids produced by microorganisms during cocoa bean fermentation penetrate the cacao bean and start the chemical reactions that will form the precursor of chocolate's flavor [11]. Additionally, the alcohols profile is desirable during cocoa fermentation because they are odor-active compounds that denote floral notes. Therefore, the use of wild yeasts that produce higher concentrations of alcohols could have favored the manufacture of flavor cocoa beans with floral notes. Esters are key compounds in the development of desirable flavors [9; 11].