## 2 Results and Discussion
### Volatile Composition  
A total of 44 compounds were identified and quantified in Cabernet Franc wines by GC-MS with HS-SPME (40, 36 and 35 different aroma compounds for F-Land, LS-Land and HS-Land, respectively), including 19 alcohols, 14 esters, five fatty acids, five aldehydes and ketones, and one phenol compound \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Analytical Parameters**} & \multicolumn{2}{c}{**F-Land**} & \multicolumn{2}{c}{**LS-Land**} & \multicolumn{2}{c}{**HS-Land**} \\ \cline{2-7}  & **Must** & **Wine** & **Must** & **Wine** & **Must** & **Wine** \\ \hline Total sugar (g/L) & 210.7 \(\pm\) 2.2 \({}^{\text{\,A}}\) & NA & 198.5 \(\pm\) 1.8 \({}^{\text{\,A}}\) & NA & 197.4 \(\pm\) 0.9 \({}^{\text{\,A}}\) & NA \\ Total acidity \({}^{1}\) (g/L) & 7.5 \(\pm\) 0.5 \({}^{\text{\,A}}\) & 9.6 \(\pm\) 0.0 \({}^{\text{\,A}}\) & 7.2 \(\pm\) 0.3 \({}^{\text{\,A}}\) & 9.3 \(\pm\) 0.2 \({}^{\text{\,A}}\) & 6.9 \(\pm\) 0.1 \({}^{\text{\,A}}\) & 9.5 \(\pm\) 0.2 \({}^{\text{\,A}}\) \\ PH & 3.2 \(\pm\) 0.1 \({}^{\text{\,A}}\) & 3.2 \(\pm\) 0.1 \({}^{\text{\,A}}\) & 3.3 \(\pm\) 0.1 \({}^{\text{\,A}}\) & 3.2 \(\pm\) 0.2 \({}^{\text{\,A}}\) & 3.1 \(\pm\) 0.1 \({}^{\text{\,A}}\) & 3.1 \(\pm\) 0.2 \({}^{\text{\,A}}\) \\ Total phenolics (mg/kg or mg/L) & 2306.2 \(\pm\) 152.4 \({}^{\text{\,A}}\) & 889.7 \(\pm\) 56.8 \({}^{\text{\,A}}\) & 2403.1 \(\pm\) 96.0 \({}^{\text{\,A}}\) & 707.4 \(\pm\) 20.5 \({}^{\text{\,B}}\) & 2306.1 \(\pm\) 102.3 \({}^{\text{\,A}}\) & 660.9 \(\pm\) 33.6 \({}^{\text{\,b}}\) \\ Residual sugar (g/L) & NA & 2.5 \(\pm\) 0.1 \({}^{\text{\,A}}\) & NA & 2.2 \(\pm\) 0.0 \({}^{\text{\,A}}\) & NA & 1.2 \(\pm\) 0.2 \({}^{\text{\,B}}\) \\ Ethanol (\%, v/v) & NA & 11.8 \(\pm\) 0.2 \({}^{\text{\,A}}\) & NA & 11.6 \(\pm\) 0.1 \({}^{\text{\,A}}\) & NA & 12.1 \(\pm\) 0.1 \({}^{\text{\,A}}\) \\ \hline \hline \end{tabular}  
* Each data in the table was meant values \(\pm\) standard deviation of triplicate samples. Different capital letters within a row for must indicated significant differences among three terrain wines by [PERSON]’s test (\(p<0.05\)). Different lower-case letters within a row for wine indicated significant differences among three terrain wines by [PERSON]’s test (\(p<0.05\)). F-Land, LS-Land and HS-Land represented flat land, low slope land and high slope land conditions of experimental vineyards, respectively. NA, not apply. \({}^{\text{\,}}\) Total acidity expressed as grams of tartaric acid equivalents per liter. \({}^{\text{\,2}}\) Total phenolics from grape must and wines expressed as milligrams of gallic acid equivalents per kilogram and milligrams of gallic acid equivalents per liter, respectively.  
\end{table} 
Table 1: General composition of the musts and wines of Cabernet Franc from the different terrains. Figure 2: The photo of the typical topography and landform in the Loess Plateau region (China). (Table 2). Moreover, alcohols and esters were the most represented compound classes in terms of the number and concentration of volatile compounds in the three terrain Cabernet Franc wines, and fatty acids, volatile phenols, aldehydes and ketones were detected as minor compounds. Many of these volatile compounds are common to most of the wines and are derived from the grape berries and yeast strains during the fermentation and the vinicification process [20]. In this study, a wide concentration range of the total volatile compounds varying from 230.1 to 367.2 mg/L was quantified in the three terrain wines. The total amounts of aroma compounds detected from HS-Land wine was the highest, while the levels in wine from F-Land were the lowest. The results in this study were consistent with the results of a previous study which was carried out with the Cabernet Sauvignon (_Vitis vinifera_ L. cultivar) wines from vineyards at different altitudes by [PERSON] et al. [18]. It is well known that the aroma of wine predominately depends on many factors, including grape variety, environmental and management practices, yeast, winemaking techniques, ageing time, etc. [13; 21].