## 3 Results
### Identification of Yeast Volatile Compounds by SPME-GC-MS  
Cell-free supernatants of the three _W. anomalous_ strains, grown under conditions in which the highest inhibitory activity against _P. chrysogenum_ was observed, were subjected to SPME-GC-MS analysis. The qualitative analysis of VOCs is summarized in Table 1. Twelve compounds were detected, among which three alcohols (ethanol, isoamyl alcohol, 2,4-di-tert-butyl-phenol) three aldehydes (benzaldehyde, nonanal, octanal), one acid (3-methyl-butanoic acid), and five esters (isoamyl acetate, ethyl acetate, butanoic acid-ethyl ester, acetic acid-butyl ester, ethyl caprylate) were identified. Ethanol, ethyl acetate, isoamyl alcohol and isoamyl acetate were detected in all samples. Ethyl acetate was the dominant compound in all samples, with ethanol and isoamyl alcohol being in relative abundance as well; the % area of these three compounds ranged between 77.6% and 89.2% of the total peak area of the samples. The rest of the volatile compounds were not produced in all conditions tested. Acetic acid-butyl ester and 2,4-di-tet-butyl-phenol were produced by all yeast strains, butanoic acid-ethyl ester and ethyl caprylate were only produced by strain LQC 10346, 3-methyl-butanoic acid and octanal by strain LQC 10353, while nonanal by both LQC 10346 and 10353. Finally, benzaldehyde was produced by strains LQC 10353 and 10360. \begin{table}
\begin{tabular}{c c c c c} \hline
**Strain/Substrate** & **pH Value** & **NaCl (\%)** & **Compound** & **Kovats Index** & **Area (\%)** \\ \hline  & & & Ethanol & \(<\)800 & 9.11 \\  & & & Ethyl acetate & \(<\)800 & 63.43 \\  & & & Isoamyl alcohol & \(<\)800 & 15.10 \\  & 6.0 & 0.0 & Butanoic acid-ethyl ester & \(<\)800 & 0.24 \\  & & & Acetic acid-butyl ester & 814 & 1.81 \\  & & & Isoamyl acetate & 879 & 0.62 \\  & & & Nonanal & 1105 & 1.25 \\ LQC 10346/BHI broth & & & Ethyl caprylate & 1197 & 0.33 \\ \hline  & & & Ethanol & \(<\)800 & 6.28 \\  & & & Ethyl acetate & \(<\)800 & 73.74 \\  & & & Isoamyl alcohol & \(<\)800 & 9.14 \\
6.0 & 1.0 & & Butanoic acid-ethyl ester & \(<\)800 & 0.16 \\  & & & Acetic acid-butyl ester & 814 & 1.48 \\  & & & Isoamyl acetate & 879 & 1.57 \\  & & & Ethyl caprylate & 1197 & 0.20 \\ \hline \end{tabular}
\end{table} 
Table 1: VOCs produced by three _W. anomalous_ strains, after a 24 h incubation at 30 \({}^{\circ}\)C, in modified BHI broth and liquid wheat dough at different pH value and NaCl combinations. Identification was performed by SPME-GC-MS. The incubation of yeast strains in liquid wheat dough resulted in the production of fewer volatile compounds, compared to those identified after growth in BHI broth. More accurately, the stable presence of ethanol, ethyl acetate, isoamyl alcohol and isoamyl acetate was detected in all samples assessed, in a strain- and substrate-independent manner. Additionally, 2,4-di-tert-butyl-phenol was identified in fewer samples; however, it was retrieved from incubation in both substrates. Regarding the VOCs identified in the _W. anomalous_ CFS after growth in BHI broth, the presence of acetic acid-butyl ester, butanoic acid-ethyl ester, ethyl caprylate, benzaldehyde, nonanal, octanal, and 3-methyl-butanoic acid was detected as well, in a strain, substrate, initial pH value and NaCl-dependent manner. Generally, the most abundant compound in every sample assessed, generated by % area, was ethyl acetate (ranging from 43.50 to 74.31%). In addition, isoamyl alcohol and ethanol were constantly detected in significant amounts as well (ranging from 9.14 to 17.67% and from 5.23 to 24.81% of total area, respectively). Acetic acid-butyl ester and nonanal exceeded 1.0% of total area in samples detected. Similar was the case for benzaldehyde, the abundance of which was recorded at 1.72% and 2.98% of total area in two assessed samples,