# Flavour Volatiles of Fermented Vegetable and Fruit Substrates: A Review
## 3 Results
### Alcohols
rhamnas_ fermented melon by-product using vacuum distillation was 6.5 ug/mL, compared to 1.3 ug/mL in the distillate from the unfermetted melon by-products, while ethanol was not detected in distillates  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Flavour Groups**} & **Volatiles** & **Flavour Notes** & **Reference** \\ \hline \hline \multicolumn{1}{c}{} & \multicolumn{1}{c}{(\(\beta\))-Citronellol} & \multicolumn{1}{c}{Floral, rose, citrus} & [19; 22] \\ \cline{2-4} \multirow{6}{*}{8} & \multicolumn{1}{c}{Myrrene} & Peppery, spicy & [22] \\ \cline{2-4}  & \multicolumn{1}{c}{Linalool} & Flower, lavender, citrus leaf, fruity & [21; 22; 35] \\ \cline{2-4}  & \multicolumn{1}{c}{D-Limonene} & \multicolumn{1}{c}{Citrus, leemon, confectionery} & [22; 35] \\ \cline{2-4}  & \multicolumn{1}{c}{Terpenes and} & \multicolumn{1}{c}{} & pineapple, fruity, arise} & [22; 35] \\ \cline{2-4}  & \multicolumn{1}{c}{(\(\Upsilon^{\prime}\))-Terpinene} & \multicolumn{1}{c}{Oily, woody, terpenic, tropical} & [22] \\ \cline{2-4}  & \multicolumn{1}{c}{Geraniol} & \multicolumn{1}{c}{Rose, geranium, sweet, floral,} & [21; 22] \\ \cline{2-4}  & \multicolumn{1}{c}{(\(\alpha\))-Terpineol} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \cline{2-4}  & \multicolumn{1}{c}{(\(\beta\))-Ionone} & \multicolumn{1}{c}{Violet} & [25] \\ \cline{2-4}  & \multicolumn{1}{c}{(\(\beta\))-Damascenone} & \multicolumn{1}{c}{Woody, sweet, fruity, earthy,} & [20; 22; 35] \\ \cline{2-4}  & \multicolumn{1}{c}{(\(\beta\))-Damascenone} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \cline{2-4}  & \multicolumn{1 prepared from the same samples using simple distillation [44]. In papaya juice, the ethanol concentration was significantly (\(p<0.05\)) increased by 7 and 11 times after fermentation by either _L. plantarum_ or _L. acidophilus_, respectively, compared to the concentration in the unfermented juice [23]. On the other hand, only small changes in ethanol were observed in two studies: (1) [PERSON] et al. [29] found that LAB fermented cherry juice had an ethanol concentration of 4.1-8.5 ng/mL, compared to 3.1-3.7 ng/mL in the unfermented juice, and (2) in watermelon juice fermented by either _L. rhamnus_, _L. plantarum_, _L. casei_, or _Pediococcus pentosaceus_ (_P. pentosaceus_), the ethanol concentration was 16.8, 15.2, 15.1, and 15 ng/mL, respectively, compared to 14.6 ng/mL in the unfermented juice; however, after fermentation by _Levilactobacillus brevis_ (_L. brevis_), the ethanol concentration was 13.9 ng/mL [48]. Six studies reported that LAB fermentation reduced the ethanol concentration in fermented fruit and vegetable juices, compared to the unfermented juices, with the synthesis of various esters speculated to have caused this decrease: (1) In unfermented Chinese wolfberry juice, the ethanol concentration was 5501.3 ug/mL, compared to 1364.7 ug/mL in the _L. acidophilus_ fermented juice, where it was not detected in the juice fermented by other LAB strains [50]; (2) in two varieties of unfermented jujube (Muzao, and Hetain) juices, the ethanol concentration was 6850, and 6130 ng/mL, respectively, compared to 5740, 5100, and 1530 ng/mL in Muzao fermented with either _L. helevticius_, _L. casei_, or _L. plantarum_, respectively, and 5380, 4400, 2660, and 2410 ng/mL in Hetain fermented with either _L. casei_, _L. acidophilus_, _L. plantarum_, or _L. helevticus_, respectively [20]; (3) in okara, the initial ethanol concentration was 44 ug/g which reduced to 20.4 and 13.8 ug/g after fermentation with LAB monoculture (_L. rhamnus_ or _Pediococcus acidilactic_ (_P. acidilactic_), respectively) and to 19.6 ug/g after co-culture fermentation (_L. acidophilus_, _L. rhamnus_, and _P. acidilactic_). However, in okara fermented with an _L.