# Study on the Kinetic Model of Mixed Fermentation by Adding Glutathione-Enriched Inactive Dry Yeast
## 3 Results
### Volatile Aroma Compounds  
Aroma is a crucial quality indicator of fruit wine, and esters and higher alcohols are the main contributors to the aromatic profile during fruit wine fermentation. In our study, we used HS-SPME-GC-MS to preliminarily identify 20 volatile aroma compounds in the wine, including 9 esters, 7 higher alcohols, and 4 aldehydes/ketones, as shown in Table 4. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**RI**} & \multirow{2}{*}{**Aroma Compounds**} & \multicolumn{3}{c}{**Mass Contents/(\(\mu\)g/L)**} \\ \cline{3-6}  & & & **TS0** & **TS20** & **TS40** & **TS100** \\ \hline
1 & 714 & Acetaldehyde & nd & 15.18 \(\pm\) 0.38 b & 18.04 \(\pm\) 0.27 c & 18.43 \(\pm\) 0.58 c \\
2 & 880 & Ethyl acetate & 1661.96 \(\pm\) 0.12 a & 1980.23 \(\pm\) 0.21 d & 1756.53 \(\pm\) 0.08 c & 1719.37 \(\pm\) 0.09 b \\
3 & 898 & Acetal & 50.25 \(\pm\) 1.27 a & 91.15 \(\pm\) 0.89 b & nd & nd \\
4 & 1094 & Isobutanol & 165.67 \(\pm\) 0.19 a & 185.94 \(\pm\) 0.35 b & 195.88 \(\pm\) 0.11 c & 198.75 \(\pm\) 0.24 d \\
5 & 1126 & Isoamyl acetate & 75.62 \(\pm\) 0.13 b & 46.81 \(\pm\) 0.1 a & 93.14 \(\pm\) 0.16 c & 113.84 \(\pm\) 0.12 d \\
6 & 1211 & Isoamyl alcohol & 2222.00 \(\pm\) 1.56 a & 2449.52 \(\pm\) 2.54 b & 2491.72 \(\pm\) 1.35 c & 2578.77 \(\pm\) 1.69 d \\
7 & 1227 & Ethyl hexanoate & 68.96 \(\pm\) 0.05 a & 96.22 \(\pm\) 0.08 d & 82.62 \(\pm\) 0.11 b & 84.07 \(\pm\) 0.09 c \\
8 & 1283 & 2-Octanone & 22.05 \(\pm\) 0.21 b & 21.20 \(\pm\) 0.31 a & 21.44 \(\pm\) 0.29 a & 22.19 \(\pm\) 0.19 b \\
9 & 1359 & N-hexanol & nd & 39.07 \(\pm\) 1.05 a & 40.18 \(\pm\) 0.33 b & 41.73 \(\pm\) 0.38 c \\
10 & 1382 & Hexyl formate & 36.22 \(\pm\) 0.63 & nd & nd \\
11 & 1441 & Ethyl octanoate & 65.37 \(\pm\) 0.19 a & 65.46 \(\pm\) 0.15 a & 69.97 \(\pm\) 0.42 b & 69.77 \(\pm\) 0.23 b \\
12 & 1528 & Benzaldehyde & 10.14 \(\pm\) 0.28 a & 10.18 \(\pm\) 0.19 a & 20.67 \(\pm\) 0.24 c & 15.14 \(\pm\) 0.14 b \\
13 & 1541 & Ethyl nonanoate & nd & 22.68 \(\pm\) 0.004 & nd & nd \\
14 & 1564 & 1-Octanol & nd & 16.11 \(\pm\) 0.38 b & nd & 14.43 \(\pm\) 0.65 a \\
15 & 1580 & 2,3-Butanediod & 32.72 \(\pm\) 0.64 b & nd & 13.96 \(\pm\) 0.35 a & 13.37 \(\pm\) 0.28 a \\
16 & 1643 & Ethyl decanoate & 27.68 \(\pm\) 0.19 b & 14.64 \(\pm\) 0.21 a & 34.42 \(\pm\) 0.15 c & 35.97 \(\pm\) 0.31 d \\
17 & 1702 & alcohol & 12.65 \(\pm\) 0.39 a & 13.12 \(\pm\) 0.24 b & 17.20 \(\pm\) 0.15 d & 14.47 \(\pm\) 0.39 c \\
18 & 1826 & Phenylethyl acetate & 66.06 \(\pm\) 0.35 a & 74.51 \(\pm\) 0.54 c & 71.39 \(\pm\) 1.02 b & 88.49 \(\pm\) 0.18 d \\
19 & 1847 & Ethyl Laurate & 10.20 \(\pm\) 0.38 b & nd & 13.65 \(\pm\) 0.26 c & 29.86 \(\pm\) 0.24 d \\
20 & 1923 & Phenylethanol & 1705.21 \(\pm\) 1.25 a & 2398.63 \(\pm\) 1.89 b & 2466.49 \(\pm\) 2.18 c & 2682.46 \(\pm\) 1.64 d \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The contents of volatile aroma compounds. Different letters represent significant differences after Duncan test, n = 3 and \(p\)-value \(<\) 0.05. Figure 4: The fitting curves of ethanol volume fraction under Boltzmann model. Esters are the main contributors to wine aroma, imparting floral and fruity notes and influencing the aroma profile and style of the wine. The relative number of esters ranged from 2012.07 to 3000.55 \(\upmu\)g/L, and TS20 and TS40 had 14.34% and 5.45% higher contents than TS0, respectively. The content of ethyl acetate and isoamyl acetate increased first and then decreased with increasing g-IDY content, reaching the maximum at 20 mg/L. This is consistent with the findings of [PERSON] et al. [33], indicating that g-IDY treatment can increase the content of phenylethyl acetate and improve wine aroma quality. Higher alcohols are produced by yeast through the Ehrlich pathway during amino acid degradation [34] and can enhance the complexity of fruity aromas and the overall taste harmony. In the present study, the higher alcohols showed significant variations in total contents among wines fermented with different g-IDY contents.