# Flavour Volatiles of Fermented Vegetable and Fruit Substrates: A Review
## 3 Results
### Alcohols
paracasei, L. acidophilus, or B. lactis_, the 1-hexanol concentration was 566.3, 728.2, and 682.2 ug/mL, respectively, where it was not detected in the unfermented juice and the juice fermented by other LAB strains [50]; (2) for kiwifruit juice (Xuxiang, and Hongyang cultivars), the 1-hexanol concentration in the Xuxiang cultivar juice fermented by either _L. acidophilus, L. helicteicus,_ or _L. plantarum_ was 11,239.2, 13,280.9, and 11,713.8 ng/mL, respectively, compared to 7054.8 ng/mL in the unfermented juice, where for the Hongyang cultivar juice fermented by either _L. acidophilus, L. helicteicus,_ or _L. plantarum_, the 1-hexanol concentration was 12,313.5, 12,357.1, and 11,461.1 ng/mL, respectively, compared to 2462.9 ng/mL in the unfermented juice [49]; (3) the 1-hexanol concentration in a distillate prepared using simple distillation of orange pomace fermented by _L. rhamnus_ was 1.1 ug/mL, compared to 0.1 ug/mL in the unfermented orange pomace distillate. In the same study, using simple distillation, the 1-hexanol concentration in fermented melon by-product distillate was 21.2 ug/mL, compared to 10.2 ug/mL in the unfermented melon by-product distillate, whereas, when using vacuum distillation, the 1-hexanol concentration in fermented melon by-product distillate was 4.3 ug/mL, compared to 0.4 ug/mL in the unfermented melon by-product distillate [44]; (4) in watermelon juice fermented by either _L. rhamnus, L. casei, L. plantarum, L. brevis,_ or _P. pentosacus_, the 1-hexanol concentration was 79.9, 121.0, 141.0, 170.0, and 171.0 ng/mL, respectively, compared to 74.7 ng/mL in the unfermented juice [48]; (5) in cherry juice fermented by either _L. plantarum, L. rhamnus,_ or _L. paracasei_, the 1-hexanol concentration was 1.9-3.5, 2.1, and 1.1 ng/mL, respectively, compared to 0.7-0.8 ng/mL in the unfermented juice [29]; (6) in okara fermented by either _L. acidophilus, L. rhamnus,_ or _P. acidilactic_, the 1-hexanol concentration was 206.7, 217, and 217.5 ug/g, respectively, compared to 64.2 ug/g in the unfermented okara. However, for okara fermented with LAB co-cultures (_L. acidophilus, L. rhamnus,_ and _P. acidilactic_), the 1-hexanol concentration reduced to 16.0 ug/g [46]; (7) in juibibe juice fermented by a mixture of _L. plantarum, L. rhamnus,_ and _S. thermophilus,_ the 1-hexanol concentration was 824 ng/g, and it was not detected in the unfermented juice [47]; (8) in apple juice fermented by either _L. plantarum, L. rhamnus, L. acidophilus,_ or _L. casei_, the 1-hexanol concentration was 21.1, 22.0, 47.4, and 52.4 ng/g, respectively, compared to 1.2 ng/g in the unfermented juice [21]; (9) in grape juice fermented by LAB, the 1-hexanol concentration was 3.3-fold higher compared to the concentration in the unfermented juice [43]; (10) in papaya juice fermented by either _L. acidophilus_ or _L. plantarum_, the 1-hexanol concentration was 3 and 4 times higher, respectively, compared to its concentration in the unfermented juice [23]; and (11) in _Momordia charantia_ juice fermented by _L. plantarum_, the 1-hexanol concentration was 2.5 times higher compared to the concentration in the unfermented juice [18]. However, the 1-hexanol concentration has also been reported to reduce after fermentation in 3 studies: (1) In goji juice fermented by different combinations of bacterial strains (either _L. plantarum, L. rhamnus, Limosiatobacillus reuteri (L. reuteri), Bacillus velezensis (B. velezensis),_ or Bacillus licheniformis (B. licheniformis)), the 1-hexanol concentration was 43.0-61.4 ng/g, compared to 80.2 ng/g in the unfermented juice [25]; (2) in tomato juice fermented by _L. plantarum_, the 1-hexanol concentration was reduced by half, compared to its concentration in the unfermented juice [32]; and (3) in mung bean fermented by _L. plantarum_, 1-hexanol was not detected, where it was detected in the unfermented bean [45]. Benzyl alcohol is an aromatic alcohol produced by microbial fermentation either from glucose [55] or the amino acid phenylalanine [56].