## 3 Results and Discussion
### Evolution of VOC Profiles During Successive Kefir Grain Passages
\begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline \hline
**No.** & **Compound** & **UKJ** & **Bev1-24 h** & **Bev2-24 h** & **Bev3-24 h** & **Bev4-24 h** & **Bev5-24 h** & **Bev5-24 h** & **Bev7-24 h** & **Bev8-24 h** & **Bev9-24 h** \\ \hline  & & & & & & & & & & & \\ \hline
23 & 2.6-Dimethyl-4-heptanone & 32.82 & 9.64 & 5.64 & 11.09 & 7.82 & 9.27 & 16.27 & 8.55 & 8.82 & 17.18 \\ \hline
24 & 2-Hepanone & – & – & – & 50.00 & 20.00 & – & – & – & – & – \\ \hline
25 & 4-Methyl-2-hexanone & – & – & – & – & – & – & – & – & 69.25 & – \\ \hline  & & & & & & & & & & & \\ \hline
26 & 2-Methylbutyl acetate & – & – & – & – & – & – & – & – & – & – \\ \hline
27 & 2-Phenylethyl acetate & – & 0.36 & – & – & – & – & – & 0.32 & – & – \\ \hline
28 & Ethyl 3-phenylpropanoate & – & – & – & – & – & – & – & – & – & – \\ \hline
29 & Ethyl butanoate & 788.89 & – & – & – & – & – & – & – & – & – \\ \hline
30 & Ethyl decanoate & – & – & – & – & 0.10 & – & – & 0.50 & – & – \\ \hline
31 & Ethyl dodecanoate & – & 0.01 & – & – & – & – & – & – & – & 0.04 \\ \hline
32 & Ethyl hexadecanoate & – & – & – & – & – & – & – & – & – & – \\ \hline
33 & Ethyl hexanoate & 42.86 & 25.71 & – & 23.57 & 9.29 & 47.14 & – & – & – & – \\ \hline
34 & Ethyl octanoate & – & 64.00 & 38.00 & 54.00 & 176.00 & – & 120.00 & – & – – & – \\ \hline
35 & Heyl acetate & – & – & – & – & – & – & – & – & – \\ \hline
36 & Methyl benzoate & – & 269.23 & – & 692.31 & 307.69 & – & – & 423.08 & – & – \\ \hline
37 & Pentiy acetate & – & – & – & – & – & – & 2.56 & – & – \\ \hline  & & & & & & & & & & \\ \hline  & & & & & & & & & & \\ \hline
38 & 2.5-Dimethyl-4-hydroxy-3(2H)-furanone & – & 14.00 & 20.00 & 203.00 & 27.00 & – & 51.00 & 22.00 & 10.00 & 110.00 \\ \hline  & & & & & & & & & & \\ \hline  & & & & & & & & & & & \\ \hline  & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 2. Cont. \begin{table}
\begin{tabular}{l l c c c c c c c c c} \hline \hline
**No.** & **Compound** & **Dev1-48 h** & **Dev2-48 h** & **Dev3-48 h** & **Dev4-48 h** & **Dev5-48 h** & **Dev5-48 h** & **Dev6-48 h** & **Dev7-48 h** & **Dev8-48 h** & **Dev9-48 h** \\ \hline \multicolumn{10}{c}{Organic acids} \\ \hline
1 & Octanoic acid & – & – & – & – & – & – & – & – & – \\ \hline \multicolumn{10}{c}{Alcohols} \\ \hline
2 & 1-Dodecanol & 6.25 & – & 38.75 & 19.38 & – & – & – & – & 6.25 \\ \hline
3 & 1-Hexadecanol & 0.57 & – & 0.45 & 0.35 & – & – & – & 0.41 & 0.68 \\ \hline
4 & 1-Hexanol & – & 5.36 & – & 26.79 & – & – & – & – & – \\ \hline
5 & 1-Octanol & – & – & – & – & – & – & – & – & – \\ \hline
6 & 1-Pentanol & 26.25 & 11.92 & 16.58 & 2.92 & 12.00 & 31.75 & 25.75 & 13.58 & 38.00 \\ \hline
7 & 1-Undecanol & 0.27 & 0.14 & 0.19 & – & – & 1.74 & 0.13 & 0.34 & 0.40 \\ \hline
8 & 2-Heptanol & – & – & – & – & – & – & – & 2.61 \\ \hline
9 & 2-Hexanol & – & – & – & – & – & – & – & – \\ \hline
10 & 2-Methyl-1-propanol & 0.58 & 0.36 & 0.53 & – & – & 1.91 & 0.24 & 0.56 & 0.49 \\ \hline
11 & 2-Nonanol & – & – & – & – & – & – & – & – \\ \hline
12 & 2-Phenylethanol & 1.35 & 1.08 & 0.76 & 0.11 & 1.38 & 2.23 & 0.92 & 1.06 & 1.91 \\ \hline
13 & 2-Undecanol & 1.95 & – & – & 6.59 & – & 6.83 & 1.71 & 2.44 & 4.63 \\ \hline
14 & 3-Methyl-1-pentanol & – & – & – & – & – & – & – & – \\ \hline
15 & Furfuryl alcohol & 0.04 & – & – & 0.03 & – & 0.04 & 0.03 & – & – \\ \hline \multicolumn{10}{c}{Aldehydes} \\ \hline
16 & (E)-2-Hexenal & – & – & – & – & – & – & – & – & 1.00 \\ \hline
17 & (E)-2-Nonneal & – & – & 1254.24 & 271.19 & – & 1457.63 & – & 338.98 & 372.88 \\ \hline
18 & 2-Methylbutanal & – & – & – & – & 60.00 & – & – & – & – \\ \hline
19 & 4-Hydroxy-3-methoxybenzaldehyde & 2.45 & 3.77 & 11.51 & 5.47 & – & 6.23 & 3.96 & 4.72 & 5.28 \\ \hline
20 & 5-Hydroymethylfurfurral & – & – & – & – & – & – & – & – \\ \hline
21 & Benzaldehyde & 0.17 & 0.21 & 0.77 & 0.39 & – & 0.71 & 0.29 & 0.31 & 0.41 \\ \hline
22 & Furfurral & – & – & – & – & – & – & – & – & – \\ \hline \hline \end{tabular}
\end{table}