## 3 Results and Discussion  
### Identification of Volatile Compounds  
The Supplementary Information (Table S1) provides a thorough description of all the volatile compounds detected per cultivar with their individual concentrations. A total of 36 volatile compounds were identified. Comparisons among cultivars were significantly different (\(p\leq 0.0001\)) for all compounds. Among these compounds, 6 were aldehydes, 6 alcohols, 10 esters, 8 lactones, 4 terpenoids, 1 carboxylic acid, and 1 ketone (Tables S1 and 2). Among the three harvest seasons, the highest number of the volatiles was detected in the peaches belonging to both the mid- and late-season cultivars (Table 3). A total of 35 volatiles were detected in both mid- and late-season cultivars, except for dodecanal and ethyl octanoate, respectively. A total of 30 volatiles were detected among early-ripening peach cultivars, with benzaldehyde, methyl hexanoate, ethyl octanoate, \(\gamma\)-octanolactone, \(\delta\)-octanactone, and \(\gamma\)-nonlactone not detected. The relative total concentration of esters per cultivar was high across all ripening seasons (Figure 1 and Table 3). The relative total concentration of alcohols per cultivar was high in early-ripening cultivars, decreasing in the mid- and late-season cultivars. The relative concentration of lactones per cultivar was high in mid-season cultivars followed by late-season cultivars (Figure 1 and Table 3). Early-season cultivars had the lowest relative concentration of lactones per cultivar. The make-up of the different classes of VOCs per season may suggest that early-season peach cultivars might have more green and grassy notes due to the higher concentrations of alcohols detected, while mid- and late-season cultivars may have an increase of peach-like aromas due to the higher concentrations of lactones. \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Classification** & **Volatile Compounds a ** & **Code b ** & **RI (Lip) d ** \\ \hline Aldehydes & Hexanal & A1 & 798 & 800 \\  & Benzaldehyde & A2 & 962 & 961 \\  & Benzeneacetaldehyde & A3 & 1048 & 1049 \\  & Nonanal & A4 & 1108.5 & 1102 \\  & Decanal & A5 & 1211 & 1195 \\  & Dodecanal & A7 & 1413.7 & 1412 \\ \hline Alcohols & (E)-3-Hexen-1-ol & B1 & 829 & 845 \\  & 2-Hexen-1-ol, (E)- & B2 & 850 & 855 \\  & Hexanol & B3 & 855 & 867 \\  & Octanol & B4 & 1075.3 & 1068 \\  & 1-Nonanol & B5 & 1172.6 & 1172 \\  & 1-Undecanol & B6 & 1371.9 & 1370 \\ \hline Esters & Methyl hexanoate & E1 & 930 & 924 \\  & 3-Hexen-1-ol, acetate, (Z)- & E2 & 1012 & 1011 \\  & Hexyl acetate & E3 & 1019 & 1010 \\  & 2-Hexen-1-ol, acetate, (Z)- & E4 & 1022 & 1007 \\  & Methyl benzoate & E5 & 1101.2 & 1106 \\  & Methyl octanoate & E6 & 1126.6 & 1128 \\  & Ethyl octanoate & E7 & 1201.1 & 1190 \\  & 2(E)-Hexenyl butanoate & E8 & 1202 & 1180 \\  & Methyl decanoate & E9 & 1327.6 & 1328 \\  & Methyl dodecanoate & E10 & 1526.3 & 1527 \\ \hline Lactones & \(\gamma\)-Hexalactone & L1 & 1061 & 1059 \\  & \(\gamma\)-Octanolactone & L2 & 1261.7 & 1260 \\  & \(\delta\)-Octalactone & L3 & 1291.4 & 1308 \\  & \(\gamma\)-Nonalactone & L4 & 1366.1 & 1363 \\  & \(\delta\)-Amyl-\(\alpha\)-pyrene & L5 & 1459.8 & 1465 \\  & \(\gamma\)-Decalactone & L6 & 1471.7 & 1463 \\  & \(\delta\)-Decalactone & L7 & 1501.6 & 1496 \\  & \(\gamma\)-Dodecalactone & L8 & 1681.1 & 1671 \\ \hline Terpenes & \(\beta\)-Myrcene & T1 & 996 & 992 \\  & D-Limonene & T2 & 1033 & 1028 \\  & Linalool & T3 & 1104.1 & 1104 \\  & Geranyl acetone & T4 & 1455.8 & 1454 \\ \hline Carboxylic acids & Benzoic acid & BA & 1165.5 & 1162 \\ \hline Ketones & \(\beta\)-Ionone & K1 & 1492.8 & 1486 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Volatile compounds detected in the fresh fruit of all 42 peach cultivars grown in Georgia, United States of America, in 2016. In this study, the total aldehydes contributed to almost 3.4% of the total flavor profile (Figure 1). Benzaldehyde (A2) was the dominant aldehyde with over 62% of the total aldehyde contribution (Figure 2).