## 2 Results and Discussion
### Characterization of Volatile Compounds
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Rention**} & \multicolumn{6}{c}{**Relative Content (\%)**} \\ \cline{3-8}  & & **Time/min** & **F0** & **L7** & **L28** & **L63** & **F63** \\ \hline
**Esters (28)** & & & & & & & \\ methyl acetate & 1.93 & nd & 0.03 & 0.07 & 0.03 & 0.06 \\ ethyl acetate & 2.35 & 0.02 & 0.08 & 0.05 & 0.06 & 0.12 \\ Methyl lutanoate & 3.66 & 0.34 & 0.29 & 0.22 & 0.44 & 0.21 \\ methyl 2-methylbutyrate & 4.18 & nd & nd & nd & 0.01 & 0.03 \\ ethyl butyrate & 4.88 & 0.70 & 0.48 & 0.12 & 0.28 & 0.04 \\ vinyl butyrate & 5.07 & nd & nd & nd & nd & 0.24 \\ ethyl 2-methylbutyrate & 5.36 & nd & 0.02 & 0.01 & 0.02 & nd \\
3-butenoic acid-3-methyl-methyl ester & 8.07 & 0.21 & 0.22 & 0.05 & 0.06 & 0.10 \\ methyl hexanoate & 11.93 & 1.97 & 2.54 & 2.05 & 1.39 & 3.33 \\
3-methyl-3-buten-1-ol acetate & 12.36 & 0.13 & 0.33 & 0.03 & 0.05 & nd \\ butyl butyrate & 13.28 & nd & 0.10 & nd & nd & nd \\ ethyl hexanoate & 13.82 & 0.77 & 1.71 & 0.12 & 0.36 & 0.03 \\
3-methyl-2-buten-1-ol acetate & 14.42 & 0.02 & 0.04 & nd & nd & nd \\
4-pentenyl butyrate & 14.94 & 2.40 & 0.66 & 0.20 & 0.19 & 0.31 \\ hexyl acetate & 15.03 & nd & 0.28 & nd & nd & nd \\ methyl octanoate & 17.84 & 0.25 & 0.32 & 0.27 & 0.15 & 1.03 \\
3-methylbutyl-2-alkenyl butyrate & 17.9 & 0.17 & 0.04 & 0.01 & 0.01 & nd \\ ethyl octanoate & 18.79 & 0.20 & nd & nd & nd & nd \\
3-methyl-3-butenoate & 19.18 & 0.77 & 0.34 & 0.04 & 0.02 & 0.05 \\ ethyl1-2-(5-methyl-5-vinyltetrahydroofuran-2-yl)-2-propyl-carbonate & 19.33 & 0.02 & 0.01 & 0.01 & 0.03 & 0.02 \\ methyl 3-(methylthio)propionate & 20.23 & 0.60 & 0.33 & 0.26 & 0.15 & 0.11 \\ ethyl 3-(methylthio)propionate & 20.98 & 1.25 & 0.29 & 0.09 & 0.09 & nd \\
3-methylbutyl-3-alkenyl isobutylate & 23.75 & 0.25 & 0.01 & nd & nd & nd \\ methyl phenylacetate & 23.90 & nd & 0.02 & 0.02 & 0.03 & nd \\ methyl salicylate & 24.10 & 0.04 & 0.09 & 0.16 & 0.27 & 0.09 \\ hexyl octanoate & 24.90 & nd & 0.23 & nd & nd & nd \\ butyric acid, di(tert-butyl)silyl ester & 24.98 & nd & 0.09 & nd & nd & nd \\ amyl 3-(methylthio)propionate & 25.7 & 0.37 & 0.02 & nd & nd & nd \\
**Alcohols (15)** & & & & & & & \\ ethanol & 2.82 & 2.44 & 2.17 & 0.12 & 1.20 & nd \\
2-methyl-3-buten-2-ol & 5.05 & nd & nd & 0.12 & 0.07 & nd \\
2-methyl-1-propanol & 7.46 & nd & 0.10 & nd & nd & nd \\
1-butanol & 10.17 & nd & 1.05 & 0.06 & nd & nd \\
2-methyl-1-butanol & 13.02 & nd & 0.63 & 0.20 & nd & nd \\
3-methyl-3-buten-1-ol & 14.24 & 3.52 & 5.57 & 2.17 & 3.30 & 0.47 \\
3-methyl-2-buten-1-ol & 16.24 & 0.21 & 0.34 & 0.12 & 0.20 & 0.07 \\
2-heptanol & 16.35 & 0.08 & 0.82 & 0.74 & 0.46 & 0.93 \\
1-hexanol & 17.04 & 0.05 & 18.31 & 2.67 & 0.04 & 0.68 \\
1-octene-3-ol & 19.04 & 0.01 & 0.01 & 0.04 & 0.14 & 0.04 \\
3,7-dimethyl-1,6-octanethiol-3-ol & 20.74 & 1.08 & 0.73 & 0.97 & 0.61 & 0.38 \\
1-octanol & 20.9 & nd & 0.58 & nd & nd & nd \\ alpha-terpineol & 23.03 & 0.18 & 0.09 & 0.22 & nd & 0.20 \\
3-(methylthio)-1-propanol & 23.22 & nd & 0.10 & 0.01 & nd & nd \\ benzyl alcohol & 25.45 & 0.02 & 0.04 & 0.06 & 0.10 & nd \\ \hline \end{tabular}
\end{table} 
Table 1: Volatile compounds of noni juice at different fermentation times and scales. Different microbial communities give different flavors during the fermentation process [43]. The microflora responsible for fermentation contributes to the aroma by utilizing constituent ingredients of plants to produce enzymes that transform natural compounds into flavor compounds [44]. Lactic acid bacteria turned the carbohydrates of fermented minced pepper into organic acids and alcohols during the fermentation process, while the organic acids and alcohols could combine with each other to form several esters, such as ethyl acetate, with pineapple flavor [45]. [PERSON] et al. [46] reported that benzaldehyde, which has a cherry-like aroma, was produced from phenylalanine by _Tetagenococcus halophilus_ degradation in soy sauce. In this study, the volatile profile obviously differed between laboratory- and factory-scale fermentation.