## 3 Results and Discussion
### Identification of Aroma Compounds in Peach Spirits  
To comprehensively research the key aroma compounds of peach spirits, and also investigate the odorant compounds responsible for the differences in aroma profiles influenced by two separation processes, samples were extracted by both LLE and SPME, analyzed using AEDA-GC-O and GC-MS, and identified according to RI, standards, aroma and mass spectrum. In distilled peach spirit, a total of 62 odorous regions were detected with FD factors ranging from 1 to 6561, including 22 esters, 9 alcohols, 6 aromatic compounds, 7 terpen, 1 acetal, 2 carbonyl compounds, 1 lactone, 8 acids, 3 sulfides, and 3 unknown odorants (Table 1). As for the pervaporation produced peach spirit, 65 odorative regions were detected, including 22 esters, 11 alcohols, 6 aromatic compounds,  
Figure 2: Comparison of aroma profiles of DS and PS. Significance: * \(p<0.05\). 5 terpenes, 1 acetal, 4 carbonyl compounds, 5 lactones, 7 acids, 1 sulfide and 3 unidentified odorants. In both peach spirits, the members of esters and alcohols were the most abundant, which was not related to the separation methods, the same as the previous report [31]. There were more terpenoids, while fewer esters, alcohols and lactones in distilled peach spirit than in pervaporation produced peach spirit. Forty-four compounds with FD factors over or equal to 9 were detected in the distilled peach spirit, while 40 compounds were in the pervaporation produced peach spirit. In both of the spirits, 3-methyl-1-butanol (malty, polish-like), phenylethyl alcohol (dried rose, sweet) and phenethyl acetate (honey, rose-like) had the highest FD values of 6561, 6561, and 2187 respectively, which meant these compounds might be important to the aroma profile of peach spirit regardless of separation methods. 3-Methyl-1-butanol and phenylethyl alcohol were also reported as important aroma compounds in peach wine and peach brandy [22; 31]. In the distilled peach spirit, ethyl acetate, isoamyl acetate, ethyl hexa-onate, diethyl succinate, 3-methyl-1-butanol, 1-hexanol, 1-heptanol, 1,1-diethoxyethane, furfural, ethyl 2-fluoroate, benzaldehyde, ethyl benzoate, benzyl acetate, phenethyl acetate, phenylethyl alcohol, citronello, (E)-\(\beta\)-damascenone, dihydro-\(\beta\)-ionol, trans-nerolidol, trans-\(\beta\)-ionone, (E,E)-farnesol, 3-methylbutanoic acid, nonanoic acid, blackberry thiophene, 3-methylthioppropanol, and one of the unknown compounds had FD factors over 27. In the pervaporation produced peach spirit, the FD factors of ethyl isovalerate, isoamyl acetate, 1-hexanol, \(\gamma\)-nonalactone, \(\gamma\)-decalactone, benzyl alcohol, (E)-\(\beta\)-damascenone, and 3-methylbutanoic acid were greater than 27. All of them might be the critical aroma compounds for the peach spirits, which should be proved furtherly. The compositional differences between distilled peach spirit and pervaporation produced peach spirit were primarily in esters, lactones, and terpenoids, according to the qualitative results and FD factors of aroma-active compounds. The numbers of esters in both peach spirits were the same, but the components were different. Ethyl dodecanoate, isoamyl decanoate, ethyl tetradecanoate, ethyl pentadecanoate and ethyl 9-decenoate were only identified as aroma-active compounds in distilled peach spirit, while ethyl isobutyrate, ethyl 2-methylbutyrate, ethyl 3-methyl-butanoate, ethyl 2-hydroxy-3-methyl butyrate and ethyl 3-hydroxybutyrate were identified as aroma-active compounds only in pervaporation produced peach spirit. In peach brandy, ethyl dodecanoate, ethyl tetradecanoate and ethyl 9-decenoate were also identified [22; 31]. In addition, the short-chain esters, including ethyl isobutyrate, ethyl isovalerate, and ethyl butanoate, were only detected or with higher FD factors in the pervaporation produced peach spirit compared to distilled peach spirit. While esters with over 14 carbon atoms were mainly detected in the distillation spirit.