## 2 Results and Discussion
### Characterization of Volatile Compounds
The relative contents of acids, alcohols, phenols and ketones of L63 were 63.08, 220.94, 170.65 and 8.89% of F63, respectively. Meanwhile, several volatile compounds identified in L63 were not detected in F63, and vice versa. The 2-heptanone was the dominant aroma compound in F63, reaching a relative concentration above 39.82%, and this may be responsible for the strongly pleasant aroma, while its content was 3.59% in L63. In short, the results of this study showed that the flavor improved in the early stages of laboratory-scale fermentation and became pungent in \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Rention**} & \multicolumn{6}{c}{**Relative Content (\%)**} \\ \cline{3-8}  & & **Time/min** & **F0** & **L7** & **L28** & **L63** & **F63** \\ \hline \multicolumn{8}{c}{**Acids (10)**} \\ cyclopentadecadecanoic acid & 1.02 & 0.04 & nd & nd & nd & nd \\ cyclohexanecarboxylic acid & 10.82 & 0.23 & 0.35 & 0.08 & 0.13 & nd \\ acetic acid & 18.76 & nd & 1.21 & 0.53 & 0.35 & 0.19 \\ sarnic acid & 20.10 & 0.07 & nd & nd & nd & nd \\
2-methylpropionic acid & 20.90 & 0.17 & nd & 0.89 & 0.46 & 0.95 \\ butyric acid & 21.85 & 1.14 & 0.85 & 2.57 & 1.41 & 0.53 \\
2-methylbutyric acid & 22.53 & 1.03 & 0.50 & 1.59 & 1.68 & 1.88 \\
2-pentenoic acid & 24.55 & nd & nd & 1.45 & nd & 0.48 \\ hexanoic acid & 25.05 & 34.08 & 21.6 & 34.17 & 36.93 & 12.20 \\ octanoic acid & 27.87 & 39.69 & 28.88 & 40.17 & 43.75 & 33.41 \\
**Ketones (7)** & & & & & & \\ acetone & 1.85 & 0.88 & nd & 0.02 & nd & 0.13 \\
2-butanone & 2.44 & nd & 0.01 & 0.05 & 0.05 & 0.12 \\
2-pentanone & 3.45 & 0.02 & 0.04 & 0.12 & 0.03 & 1.15 \\
2-heptanone & 11.56 & 3.64 & 6.59 & 6.71 & 3.59 & 39.82 \\
2-nonanone & 17.74 & 0.07 & 0.08 & 0.08 & 0.03 & 0.38 \\
2-octene-4-one & 19.49 & 0.03 & 0.03 & 0.01 & nd & nd \\
5-butyldihydro-2(3H)-furanone & 25.98 & 0.01 & 0.01 & 0.06 & nd & nd \\
**Aldehydes (5)** & & & & & & \\ acetaldehyde & 1.50 & nd & 0.11 & nd & nd & nd \\ hexanal & 6.20 & nd & 0.20 & nd & nd & nd \\ Octanal & 15.33 & 0.01 & 0.03 & nd & nd & 0.05 \\ benzaldehyde & 20.10 & nd & nd & 0.02 & 0.01 & 0.03 \\
2,4-dimethylbenzaldehyde & 24.57 & nd & 0.16 & nd & 0.07 & nd \\
**Alkanes (4)** & & & & & & \\ cyclotriazane & 2.16 & 0.03 & nd & nd & nd & nd \\
6-methyltriadecane & 22.25 & 0.04 & nd & nd & nd & nd \\
8-hexyl-pentadecane & 24.84 & nd & 0.14 & ns & nd & nd \\
2,6,11-trimethyl-dodecane & 24.91 & nd & nd & nd & 0.26 & nd \\
**Amides (2)** & & & & & & \\ erucamide & 32.04 & 0.30 & nd & nd & 0.68 & nd \\ oleic acid amide & 32.3 & 0.29 & nd & nd & 0.15 & nd \\
**Phenols (2)** & & & & & & \\
2-methoxy-3-(2-ene)-phenol & 29.12 & 0.11 & 0.05 & nd & nd & 0.12 \\ eugenol & 29.13 & nd & nd & 0.17 & 0.63 & nd \\
**total** & & & & & & \\ \hline \hline \end{tabular} The value expressed as a percentage of total volatile compounds. nd means not detected.  
\end{table} 
Table 1: _Cont._the late stages of fermentation. At the same time, the result of volatile profile analysis suggested that the flavor of noni juice of factory-scale fermentation may be preferred to that of laboratory-scale fermentation.