## 3 Results and Discussion
### Quantification and OAV Analysis of Aroma Compounds  
To further analyze the differences in aroma characteristics between peach spirits produced by distillation or pervaporation, a total of 53 compounds out of 85 compounds identified by GC-O were quantified using either DI-GC-MS, LLE-GC-MS or HS-SPME-GC-MS (Table 2). Other qualitative compounds were not quantified due to a lack of standards or trace concentration. For quantitative analysis, the standard curves of all compounds were constructed using the internal standard method, exhibited good linear correlation coefficients (R\({}^{2}\) > 0.990), and the relative standard deviation (RSD) of the triplicate samples was \(\leq\)15%. Details were shown in Table S2. OAVs were calculated to evaluate the contribution of aroma compounds in the alcoholic beverage matrix (Table 2). A compound is considered to have a contribution to the aroma profile when its OAV is greater than 1. The different OAV and FD values for the same compound are due to its different thresholds in the different matrixes. Fourteen aroma compounds with OAVs \(\geq 1\) were found in distilled peach spirit, and 21 aroma compounds with OAVs \(\geq 1\) were identified in the pervaporation produced peach spirit. In both of the peach spirits, the OAVs of isoamyl acetate, ethyl hexanoate, 3-methyl-1-butanol,1,1-diethoxyethane, and (E)-\(\upbeta\)-damascenone were relatively higher than other compounds, and their FD factors were also markedly high, which certified the importance of these compounds to the overall aroma of the peach spirit. While phenethyl acetate, phenethyl alcohol and 3-methylbutanoic acid, with obviously high FD factors, had significantly low OAVs, even below 1. Most esters contribute fruity and floral sensory properties to wines and spirits. The total concentration of all the esters in the pervaporation produced peach spirit was more than in the distilled peach spirit. In the distilled peach spirit, there were 5 esters having greater concentrations than their thresholds, while 8 esters were quantified in the pervaporation produced peach spirit with OAVs \(\geq 1\). The OAVs of isobutyl acetate, ethyl isovalerate, and ethyl hexanoate in the pervaporation produced peach spirit were significantly higher than those in the distilled peach spirit, especially ethyl hexanoate, which contributed sweet and  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No. **} & \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**CAS**} & \multirow{2}{*}{**Odor De-**} & \multirow{2}{*}{**Identification**} & \multirow{2}{*}{**RI b**} & \multicolumn{3}{c}{**FD Factor**} & \multirow{2}{*}{**PS**} \\ \cline{5-8}  & & & & & & & **LLE c** & & **LLE c** & \\  & & & & & & **(AF/NBF)** & & **(AF/NBF)** & & **(AF/NBF)** & \\ \hline \multirow{4}{*}{78} & **Sulfides** & & & & & & & & & \\  & Blackberry & 13679-85- & \multirow{4}{*}{ \begin{tabular}{} \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{} \end{tabular}  } & MS, RI, & & & & & \\  & 1 & & & & & & & & \\  & 3- & & & & & & & & \\  & Methylthiopropanol & 505-10-2 & \multirow{4}{*}{\ \begin{tabular}{} \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{} \end{tabular}  } & MS, RI, & & & & & \\  & & & & & &  
fruity aroma. [PERSON] et al. [18] reported that compared to the raw wine sample, the contents of ethyl acetate and ethyl hexanoate were concentrated 5.94 times and 1.74 times, respectively, after being separated by the pervaporation process. It indicated pervaporation process was probably positive to concentrate these esters. While ethyl butanoate and ethyl octanoate had higher OAVs in the distilled peach spirit compared to pervaporation produced peach spirit. A similar result was also reported in Cognac produced by Charente pot distillation, that ethyl octanoate and ethyl butanoate had high concentrations and important contributions to brandy [36].