# Screening Wild Yeast Isolated from Cocoa Bean Fermentation Using Volatile Compounds Profile
## 2 Results and Discussion
### Principal Component Analysis (PCA)  
PCA was carried out to visualize the relationship between volatile compounds and yeasts. The biplot shows that the first two principal components explained 44% of the total variance. According to the loading plot (Figure 4), 33 strains of yeasts were characterized by their relationship with fruit perception. The results showed that yeasts, Y218 and Y73, were grouped at the positive PC1 region, and ethyl acetate (C6, pineapple), were associated with this region. Additionally, Y110-mrs yeast was located in positive values of this component, positively correlating with the volatile compounds 2-phenylethyl acetate (C11, fruity, honey) and 3-methylbutyl acetate (isoamyl acetate) (C7, banana). While Y231 was associated with ethyl decanoate (C15, fruity). The presence of these esters has been associated with a fruity perception (Mersman). Ethyl acetate, 2-phenyl ethyl acetate, and 3-methyl butyl acetate (isoamyl acetate) were quantitatively the most prominent acetate esters, and their concentration varied between strains. Of all yeasts, Y110-mrs presented the highest concentrations of 2-phenyl ethyl acetate (317.18 \(\pm\) 9.69 mg/kg) and 3-methyl butyl acetate (isoamyl acetate (218.03 \(\pm\) 19.02 mg/kg)).  
The strains Y195 and Y246 were placed in the negative PC2 region, and 3-methyl butanol (C2, malty), 2-phenyl ethanol (C4, floral), phenylacetaldehyde (C17, nutty, honey), 3-methyl butanal (C16) were related with floral and sweet perception. Concentrations 51.45 mg/kg of 2-phenyl ethanol (C4, floral), 65.43 mg/kg of 3-methyl butanol (C2, malty), and phenylacetaldehyde (C17, nutty, honey) 12.22 mg/kg were found in Y195. While Y246 reached concentrations of 38.52 mg/kg of 2-phenyl ethanol (C4, floral), 34.92 mg/kg of 3-methyl butanol (C2, malty), and phenylacetaldehyde (C17, nutty, honey) 54.08 mg/kg. Compounds ethyl decanoate (C12, pear, grape, brandy), ethyl 3-phenylpropionate (C13, fruity), and acids were grouped in the positive region of PC1 but they were not related to yeasts.  
The cluster analysis for yeasts (Figure 5) presented four main groups. Cluster 1 includes strain Y87, which is related to esters, alcohols, and carboxylic acids. Cluster 2 consisted of strains Y195 and Y246, which had the greatest floral contributions. Cluster 3 is constituted by strain Y200, which has the ability to produce 2-phenyl ethanol and methyl propyl acetate, associated with floral and fruity perceptions. The last group (cluster 4) was constituted by strains Y01, Y04, Y11c, Y12, Y13a, Y17, Y19, Y29a, Y33, Y52, Y73, Y85, Y92a, Y92c, Y97, Y105, Y109 sba, Y110 ms, Y111, Y112b, Y117, Y133, Y137, Y163, Y173 mrs, Y187, Y218, Y231, Y233, Y236, Y214b, and Y244. It should be noted that the majority of yeasts analyzed are found in cluster 4 and these yeasts produced esters frequently associated with fruity perceptions, which agrees with the typical fruity sensorial profile of Colombian cocoa [18].  
Figure 4: PCA Biplot of volatile compounds produced by yeasts isolated from cocoa pulp-bean mass fermentation of Santander, Colombia. The number of volatile compounds (red) is presented in Table 2. Strains yeast (Blue).  
Figure 5: Cluster analysis of cocoa bean yeasts. Strains were grouped based on their VCs production using [PERSON]’s method.