## 3 Results and Discussions
### Chemometrics
 & C\({}_{31}\)H\({}_{24}\) & 16729-01-4 & 904 & 1522 & - & x & - & x & - & - & - \\ \hline \begin{tabular}{c} cis-amamere \\ \end{tabular}  & C\({}_{31}\)H\({}_{22}\) & 72937-55-4 & 869 & 152  
Template matching revealed 46 compounds that were exclusively in one sample or in both, but with distinguished intensities. Table 1 summarizes all the compounds identified by the approach described herein. According to the data of Table 1, ENG brewing enabled retention/formation of higher alcohols and monoterene alcohols. Template matching identified compounds that were present in higher quantities in the ENG sample, including alcohols and esters. These chemical classes are known to enhance fruity notes to the sample; examples include cis-geraniol; trans-geraniol and 2-phenylethylly acetate. Furthermore, the chemometric approach highlighted that the _Brazilian Ale 02_ yeast supported the formation and/or retention of terpenic compounds in the beer. The terpenidy cryophyllene oxide, beta-pinene, and cryophyllene contribute to enhance spicy aromas and flavors in the beer, corroborating the information presented in the datasheet of the _Brazilian Ale 02_ yeast [34]. Classification of terpenic compounds depends on the number of repetitions of the isoprene unit (C\({}_{5}\)H\({}_{8}\)), being monoterpenic compounds (two isoprene units), sequiterpene compounds (three isoprene units) and so on [35]. Their presence in a beer comes mostly from the hops added during brewing, which act as preservative and impart the bitterness characteristic of beers [23]. A minor source to these chemical compounds may be the yeast's metabolism. [PERSON] et al. [36] demonstrated that ale and lager yeasts are capable of bitransforming the monoterene alcohols trans-geraniol and linalool into other monoterene alcohols or esters. Finally, template matching provided conditions to the identification of the bioaromatization properties introduced in the aroma profile of the beer by the unique Brazilian yeast. The approach enabled the identification of seven compounds that were found exclusively in the BR samples, chemical classes found include esters (ethyl phenylacetate; ethyl decanoate; isoamyl octanoate; ethyl dodecanoate), terpen (\(\gamma\)-muurolene; aromadendrene) and a phenolic compound (4-vinylguaiacol). Unfortunately, due to synergistic and antagonistic effects it is difficult to know what will be the effect that different levels of higher alcohols and esters will have on the overall profile of the beer [27]. Therefore, the data analyzed provided general answers about the aroma that compounds can impart to  
Figure 5: (**a**) Peak template creation using the loadings vector and the reconstructed chromatogram; (**b**) Process of template matching using GC Image highlighting potential unique compounds in the GC\(\times\)GC-QMS total ion chromatogram of the BR beer sample. the beer. These findings highlight the necessity of alloying a sensory panel of specialists to taste beer samples and to elucidate the influence of such compounds to the aroma of beers. Furthermore, there is a threshold in which a compound with a concentration lower than that will not be perceived, but also due to synergistic effects the presence of different esters can affect beer flavor even if they are well below their individual threshold concentrations [27]. This is valid for both desired and undesired molecules. Examples of undesired compounds (off-flavors) and their individual sensory threshold in beers include the esters isoamyl acetate (1400 ng mL\({}^{-1}\)); ethyl acetate (15,000 ng mL\({}^{-1}\)); ethyl hexanoate (200 ng mL\({}^{-1}\)) and 2,3-butanedione (40 ng mL\({}^{-1}\)) [37]. Ethyl hexanoate and isoamyl acetate were both detected in BR and ENG, which highlights how difficult it is to produce beers without off-flavors.