# Bioconversion of Apple Pomace to _Meyerozyma guilliermondii_ and _Scheffersomyces stipitis_ Biomass
## 3 Results and Discussion
### Sugars, Organic Acids, and Alcohols in the AP Hydrolysates  
Tables 2-4 show the content of selected simple sugars, organic acids, glycerol, and ethanol in the AP hydrolysates. \begin{table}
\begin{tabular}{c c} \hline \hline  & **Value** \\ \hline Dry matter [\%] & 90.68 \(\pm\) 2.7 \\ Cellulose [\% DM] & 15.42 \(\pm\) 0.3 \\ Hemicellulose [\% DM] & 12.45 \(\pm\) 0.09 \\ Lignin [\% DM] & 15.23 \(\pm\) 0.12 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dry matter and basic components of AP used in our experiments. Our experiment began with the pretreatment of apple pomace, conducted at a temperature of 121 \({}^{\circ}\)C for 1 h, using water or 2% H\({}_{2}\)SO\({}_{4}\) as medium. Comparing the data in Table 2 between sample A (acid-assisted pretreatment) and sample W (water used as a medium), it is evident that pretreatment with 2% sulphuric acid released substantial amounts of free sugars from the raw material, particularly glucose (7.258 g/L), xylose (7.19 g/L) and arabinose (5.659 g/L). The sulphuric acid also catalysed the release of cellobiose from the lignocellulosic matrix; 0.91 g/L of this sugar was detected after acid pretreatment, while only 0.081g/L of cellobiose was found in the reference sample, where water was used as the medium. Additionally, significant amounts of galacturonic acid were observed in the pretreated samples: 0.315 g/L in the water-treated sample (W) and three times higher at 0.947 g/L in the acid-assisted pretreatment (sample A). The aqueous pretreatment did not significantly affect the amount of sugars available. However, the primary purpose of pretreatment is to modify the structure of the raw material to enhance enzymatic accessibility. The release of sugars during pretreatment can sometimes be disadvantageous, as it hinders the removal of the reactants used in the pretreatment stage, leading to a loss of the already released monosaccharides. Looking at the results for the WE and AE samples, obtained after enzymatic hydrolysis at 30 \({}^{\circ}\)C or 50 \({}^{\circ}\)C, an increase in the content of all sugars and galacturonic acid was observed compared to the W and A samples (before enzymatic hydrolysis). The cellobiose content at this stage ranged from 0.787 g/L to 1.485 g/L, with the lowest value in the WE50 sample, and the highest in the acid-pretreated sample hydrolys at 30 \({}^{\circ}\)C. Glucose content ranged from 14.866 g/L (in the sample obtained after 2% acid pretreatment and enzymatic hydrolysis at 30 \({}^{\circ}\)C) to 19.311 g/L (WE30 sample). After enzymatic hydrolysis, the amount \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Sample**} & **GOH** & **EOH** \\  & & **[g/L]** & \\ \hline W & 0.679 \(\pm\) 0.0249 & 0.036 \(\pm\) 0.0013 \\ A & 0.678 \(\pm\) 0.0206 & 0.011 \(\pm\) 0.0004 \\ WE50 & 0.742 \(\pm\) 0.0061 & 0.01 \(\pm\) 0.0003 \\ AE50 & 0.74 \(\pm\) 0.0255 & 0.012 \(\pm\) 0.0005 \\ WE30 & 0.687 \(\pm\) 0.0216 & 0.022 \(\pm\) 0.0009 \\ AE30 & 0.775 \(\pm\) 0.0249 & 0.056 \(\pm\) 0.0015 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Glycerol and ethanol content in the AP hydrolysates. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Sample**} & **CEL** & **GLU** & **XYL** & **ARA** & **GA** \\  & & & **[g/L]** & & \\ \hline W & 0.081 \(\pm\) 0.003 & 0.06 \(\pm\) 0.0032 & 0.21 \(\pm\) 0.0052 & 0.131 \(\pm\) 0.0038 & 0.315 \(\pm\) 0.0029 \\ A & 0.91 \(\pm\) 0.052 & 7.258 \(\pm\) 0.1798 & 7.19 \(\pm\) 0.3013 & 5.659 \(\pm\) 0.1159 & 0.947 \(\pm\) 0.0272 \\ WE50 & 0.787 \(\pm\) 0.0291 & 18.55 \(\pm\) 0.6058 & 5.76 \(\pm\) 0.1958 & 5.348 \(\pm\) 0.0665 & 7.013 \(\pm\) 0.3713 \\ AE50 & 1.44 \(\pm\) 0.0246 & 18.325 \(\pm\) 0.8415 & 7.61 \(\pm\) 0.2352 & 5.592 \(\pm\) 0.17 & 6.23 \(\pm\) 0.3561 \\ WE30 & 1.228 \(\pm\) 0.0365 & 19.311 \(\pm\) 0.8692 & 4.96 \(\pm\) 0.1071 & 5.15 \(\pm\) 0.2943 & 6.785 \(\pm\) 0.277 \\ AE30 & 1.485 \(\pm\) 0.0583 & 14.866 \(\pm\) 0.6147 & 7.92 \(\pm\) 0.2332 & 5.669 \(\pm\) 0.3002 & 6.438 \(\pm\) 0.2378 \\ \hline \hline \end{tabular}
\end{table}