# Aromatic Potential of Diverse Non-Conventional Yeast Species for Winemaking and Brewing
## 3 Results and Discussion
### Microwine
#### 3.1.2 Aroma Profiles
\begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \ \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  \\ \hline \hline \multicolumn{11}{l}{Lalvin T73} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & 26 \({}^{+}\) & 24 \({}^{+}\) & **33** \({}^{1}\) & 3 \({}^{+}\) & **1.54** \({}^{\rm hc}\) & **1.98** \({}^{\rm a}\) & **0.55** \({}^{\rm a,b}\) & **1.43** \({}^{\rm c}\) & **0.57** \({}^{\rm c,d}\) \\ CB872.71 & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & 12 \({}^{\rm a}\) & 23 \({}^{+}\) & **17** \({}^{\rm d,g}\) & 4 \({}^{\rm a-c}\) & **0.81** \({}^{\rm a}\) & 23.79** \({}^{\rm c}\) & **0.12** \({}^{\rm a,b}\) & **0.22** \({}^{\rm a,b}\) & **0.26** \({}^{\rm a-d}\) \\ CB872.72. Acetate esters are desirable aroma compounds presenting a wide range of fruity flavours and are of special interest inthe case of young wines produced from neutral grape varieties [18]. Among the most important acetate esters present in alcoholic beverages are ethyl acetate (naiL polish, fruity; sensory threshold: 7.5 mg/L), isoamyl acetate (banana, pear; sensory threshold: 0.03 mg/L) and phenylethyl acetate (flowery, rose, fruity, honey; sensory threshold: 0.25 mg/L) [13]. Multifactorial ANOVA points out that non-_Saccharomyces_ strain and type of culture, mixed or pure, significantly affected acetate ester yields. Reference microwine did not excel in the amounts of any acetate ester and isoamyl acetate was missing in most of the mixed cultures (Table 4), indicating a negative interaction between _Saccharomyces_ and non-_Saccharomyces_ strains regarding this aroma compound. Despite being the main acetate ester in wine, ethyl acetate only appeared above its sensory threshold in four pure cultures: _H. guillermondii_ CBS 2567, _W. subpelliculosus_ CBS 5552, _S. caribaea_ CBS 7692 and _K. gamospora_ CBS 10400 (Table 5). Excessive acetate ester production, a trait traditionally linked to non-_Saccharomyces_ strains, can negatively affect the aroma profile, giving \"oxidised\" notes [17; 18; 23]. However, in our study this seems not to be the case. Similarly, in the case of isoamyl and phenylethyl acetate, pure cultures yielded significantly higher amounts (Table 4), indicating high activity of the acetyltransferases, which must be inhibited to a certain degree in mixed cultures. A remarkable example in this sense is the strain _S. caribaea_ CBS 7692, since its huge acetate ester production was not shown when combined with _S. cerevisiae_ (Table 4). This extraordinary acetate ester synthesis of _S. caribaea_ CBS 7692 when used as pure culture was already described in previous works, where this strain and _H. guillermondii_ CBS 2567 produced from 44- to 84-fold the levels found in reference _S. cerevisiae_ pure culture [11; 22]. _H. guillermondii_ CBS 2567 also excelled in the production of phenylethyl acetate and the precursor alcohol when fermenting cashew apple juice [21]. In our study, acetate ester production by _H. guillermondii_ CBS 2567 was not so huge, but still remarkable (Table 4).