## 3 Results and Discussion
### Chemical Composition of the Obtained Distillates  
During the fermentation process, yeast produces ethanol and carbon dioxide, which facilitate the synthesis of alcohols, esters, and organic acids. The chemical composition of the obtained agricultural distillates was evaluated, revealing a differential effect of the type of bread used and the method of sweet mesh preparation (see Table 4). The undesirable compound present in spirit distillates is methanol, which is generated through the hydrolysis of methylated pectins present in plants and fruits, which may also occur during the backing process. [PERSON] et al. [51] observed a higher concentration of methanol in the spirits obtained from starchy raw materials-based mashes prepared by the pressure-thermal method (approx. 150 \({}^{\circ}\)C) than with the pressureless method (90 \({}^{\circ}\)C). While EU Regulation No. 2019/787 [53] defines acceptable concentrations of methanol in ethyl alcohol of agricultural origin, wine spirits and fruit spirits, no limits are set for the content of this compound in distillates of agricultural origin. It should be noted, however, that all the obtained distillates comply with the requirements set out in the regulation, which stipulates that the maximum permitted methanol content in ethyl alcohol of agricultural origin (rectified spirit) shall be 30 g/hL absolute alcohol (equivalent to 300 mg/L). Aldehydes present in spirits are intermediates in the two-step decarboxylation of alpha-keto acids to alcohols, as well as in the synthesis and oxidation of alcohols. These volatiles are often found to have a negative effect on the quality of spirits. Their concentration depends on the quality of the raw materials, their chemical composition, the \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter** [g/l. alcohol] **100\% v/l/e]**} & \multicolumn{4}{c}{**Wheat Bead-Based Mashes**} & \multicolumn{4}{c}{**Wheat-Rye Bead-Based Mashes**} \\ \cline{2-13}  & **PLS-SSF** & **PLS-SHF** & **NSH-N/A** & **PLS-SSF** & **PLS-SHF** & **NSH-N/A** & **NSH-A** \\ \cline{2-13}  & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** \\ \hline Methanol & 0.200 \({}^{\text{b}}\) & 0.04 & 0.240 \({}^{\text{b}}\) & 0.03 & 0.200 \({}^{\text{b}}\) & 0.03 & 0.150 \({}^{\text{b}}\) & 0.02 & 0.300 \({}^{\text{b}}\) & 0.08 & 0.210 \({}^{\text{b}}\) & 0.02 & 0.190 \({}^{\text{b}}\) & 0.03 \\ aldehydes & 0.170 \({}^{\text{c}}\) & 0.01 & 0.120 \({}^{\text{d}}\) & 0.01 & 0.160 \({}^{\text{c}}\) & 0.02 & 0.220 \({}^{\text{a}}\) & 0.02 & 0.180 \({}^{\text{b}}\) & 0.01 & 0.233 \({}^{\text{a}}\) & 0.02 & 0.210 \({}^{\text{a}}\) & 0.01 \\ \multicolumn{2}{c}{Acidity} & \multicolumn{4}{c}{0.620 \({}^{\text{d}}\)} & 0.01 & 0.940 \({}^{\text{a}}\) & 0.04 & 0.723 \({}^{\text{a}}\) & 0.05 & 0.583 \({}^{\text{a}}\) & 0.04 & 0.620 \({}^{\text{a}}\) & 0.01 & 0.710 \({}^{\text{c}}\) & 0.01 & 0.850 \({}^{\text{b}}\) & 0.02 \\ \hline \hline \end{tabular}  
* The results expressed as mean values \(\pm\) SD (n = 3); mean values with different letters (a, b, c, etc.) within the same row are significantly different (ANOVA, \(p\) < 0.05).  
\end{table} 
Table 4: Chemical composition of the waste bread-based spirit distillates. conditions of the technological processes and microbial contamination [54]. According to the Polish Standard [55], the concentration of aldehydes, expressed as acetaldehyde, in agricultural distillates should not exceed 100 mg/L alcohol 100% \(v/v\), while the EU regulation [53] does not set any limits for the acetaldehyde content in agricultural distillates. The concentrations of aldehydes (expressed as acetaldehyde) in the obtained bread-based distillates exceeded the recommended limit, and ranged from 0.120 \(\pm\) 0.01 to 0.233 \(\pm\) 0.02 g acetaldehyde/L alcohol 100% \(v/v\). The average content of these compounds was higher (\(p\leq\) 0.05) in the distillates obtained from wheat-rye bread than from wheat bread.