## 3 Results and Discussion
### Volatile Composition of Beverages Obtained through Static Discontinuous Fermentations I and II
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Volatile Compound** & **OPT (\(\mu\)g/L)** & **Odor Descriptors** & **Series** \\ \hline \multicolumn{4}{c}{Organic acids} \\ \hline Acetic acid & 99,000.00 [45] & Vinegar, sour [46; 47] & 1 \\ Butanoic acid & 1400.00 [45] & Sweaty, butter, cheese, acid, fermented odor [48] & 1 \\ Pentanoic acid & 3000.00 [45] & Green fruit, vegetables, sweat [14; 49] & 1, 4 \\ Hexanoic acid & 3000.00 [45] & Goat cheese, fatty acids, vegetable oil, sweaty, sharp, & 1, 2, 4 \\ Hexanoic acid & 3000.00 [45] & acidic, green, gammy, dairy sour, dairy, stale, butter, sour, & 1, 2, 4 \\  & & fruity, and pungent [8; 46; 48; 50; 51] & \\
2-Ethyl-hexanoic acid & 27,000.00 [45] & Taste similar to paint [52] & 5 \\
2-Methyl-propanoic acid & 6550.50 [45] & Fruits [14] & 2 \\ Hepanoic acid & 640.00 [45] & Cheese [50] & 1 \\ Octanoic acid & 3000.00 [45] & Sweat, cheese, rancid, fatty acids, vegetable oil [50; 53] & 1 \\ Nonanoic acid & 8800.00 [45] & Fatty, soapy, waxy, green, goat [54] & 1, 4 \\ \hline \multicolumn{4}{c}{Alcohols} \\ \hline
1-Pentanol & 120.00 [45] & Green fruit, fermented, bread and yeast [12; 50; 55] & 1, 2 \\
2-Phenylethanol & 564.20 [45] & Floral, pink, flowery, like honey [50; 53; 56; 57] & 3, 7 \\
2-Methyl-1-propanol & 550.00 [45] & Wine, solvent, bitter, malty [58; 59; 60] & 5, 6 \\
1-Heptanol & 5.40 [45] & Fat [61] & 1 \\
2-Heptanol & 65.23 [45] & Green [14; 50] & 4 \\
2,4-Dimethyl-3-pentanol & 82.00 [45] & Bitter almond [62] & 2 \\
2-Ethyl-hexanol & 830.00 [45] & Leather, goat, stable, cow and sheep, cardboard [48; 54] & 5, 6 \\
3-Methyl-1-pentanol & 7.50 [45] & Unpleasant chemical fused [63] & 5 \\
2-Furanmethanol & 4500.00 [45] & Floral, sweet [64] & 6 \\ Butane-1,3-diol & 10,000.00 [45] & Greasy, floral [65] & 1, 3 \\ \hline \multicolumn{4}{c}{Aldehydes} \\ \hline \multicolumn{4}{c}{(E)-2-Noncal} & 0.40 [45] & Fatty, green [60] & 1, 4 \\
2-Ethyl hexanal & 41.00 [45] & Legume smell [66] & 1 \\ Benzaldehyde & 750.00 [45] & Almond, nut-like bitter [50; 66] & 2 \\ Dodecanal & 10.00 [45] & Floral, waxy [67] & 1, 3 \\ Phenylacetaldehyde & 6.30 [45] & Honey [50] & 7 \\ Nonanal & 1.10 [45] & Green, fresh, citrus-like, soapy, fruity odor [50; 53; 68] & 2, 4 \\ \hline \multicolumn{4}{c}{Ketones} \\ \hline
2,6-Dimethyl-4-heptanone & 110.00 [69] & Fruity, sweet [8] & 2 \\
2-Heptanone & 5.00 [70] & Banana, fruity, floral and musty, fresh cream flavor & 1, 2, 3 \\
2-Nonanone & 5.00 [70] & Sweet, fruity, floral, musty [50; 68] & 2, 3 \\
5-Methyl-3-heptanone & 41.00 [45] & Fruit [71] & 2 \\ \hline \multicolumn{4}{c}{Esters} \\ \hline
2-Phenethyl acetate & 249.59 [45] & Floral, rose, honey [72] & 3, 7 \\ Ethyl acetate & 5000.00 [72] & Pineapple, fruit [15; 50; 73] & 2 \\ Isoamyl acetate & 2.00 [45] & Banana, fruity, sweet [50; 74] & 2 \\ Pentyl acetate & 43.00 [45] & Fruit [72] & 2 \\ Decyl butanoate & 250.00 [75] & Fruity, waxy, fatty, and slightly citrus [76] & 1, 2 \\ Ethyl decanoate & 23.00 [45] & Apple, floral, fruity, and musty [15; 72; 77] & 2, 3 \\ Ethyl dodecanoate & 5900.00 [45] & Fruity, floral [72] & 2, 3 \\ Ethyl heptanoate & 1.90 [45] & Fruit, overripe [50; 72] & 2 \\ Ethyl hexanoate & 1.00 [45] & Banana, apple [72; 78] & 2 \\ Ethyl octanoate & 19.30 [45] & Fruity, apple, banana [72; 78] & 2 \\ Ethyl phenylacetate & 250.00 [76] & Sweet fragrance of honey [50] & 7 \\ Ethyl nonanoate & 377.00 [45] & Floral, fruit [67; 72] & 2 \\ Ethyl isobutanoate & 0.10 [45] & Unripe fruit [79] & 2, 4 \\ Octyl butanoate & 250.00 [45] & Herb, orange, flower [80] & 2, 3, 4 \\ Hexyl propanoate & 8.00 [45] & Apple [81] & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Olfactory perception threshold (OPT, \(\mu\)g/L), odor descriptors, and aroma series for the volatile compounds identified in unfermetered and fermented UHT milk with kefir grains in the four consecutive 24- or 48-h subcultures.