# Flavour Volatiles of Fermented Vegetable and Fruit Substrates: A Review
## 3 Results
### Terpenes and Norisoprenoids
_thermophilus_, and it was not detected in the unfermented yarn juice [33]; and (7) in mango slurry fermented by LAB, linalool was detected, where it was not detected in yeast fermented or unfermented slurry [41]. Though the linalool concentration increased in these studies after fermentation, it was also reduced after fermentation in 2 studies: (1) In papaya juice fermented by either \(L\). _acidophilus_ or \(L\). _plantarum_, the linalool concentration was 1.6 and 1.2 times lower, respectively, compared to the concentration in the unfermented juice [23]; and (2) in _Momordia charantia_ juice fermented by \(L\). _plantarum_, the linalool concentration was reduced compared to the concentration in the unfermented juice [18]. D-limonene, a significant flavour terpene compound, increased in 8 experiments after the fermentation of juices: (1) In Chinese wolfberry juice fermented by either _L. casei_, _L. paracasei_, _L. acidophilus_, _L. heleticus_, or _B. lactis_, the D-limonene concentration was 281.4, 218, 372.6, 271.8, and 273.5 \(\upmu\)g/mL, respectively, compared to 143.5 \(\upmu\)g/mL in the unrefmented juice, where in fermented juice by _L. plantarum_, the D-limonene concentration was 67.4 \(\upmu\)g/mL [50]; (2) the D-limonene concentration in distillates prepared using vacuum distillation from _L. rhamns_ fermented melon by-product or unfermented melon by-product was 140 ng/mL and 10 ng/mL, respectively. In the same study, distillates prepared using vacuum distillation had concentrations of 100 ng/mL and 20 ng/mL in the _L. rhamns_ fermented orange pomace distillate and the unfermented pomace distillate, respectively [44]; (3) in cherry juice fermented by either _L. rhamns_ or _L. paracasei_, the D-limonene concentration was 7.9 and 3.0 ng/mL, respectively, compared to 2.8 ng/mL in the unfermented juice, where in cherry juice fermented by four _L. plantarum_ strains, the D-limonene concentration was 1.8, 1.9, 3.1, and 4.0 ng/mL, compared to 2.3 ng/mL in the unfermented juice [29]; (4) in jujube juice fermented by a mixture of _L. plantarum_, _L. rhamns_, and _S. thermophilus_, the D-limonene concentration was 964 ng/g, where it was not detected in the unfermented juice [47]; (5) in apple juice fermented by different LAB, the D-limonene concentration ranged from 2.5 to 3.1 ng/g, compared to 1.1 ng/g in the unfermented juice [21]; (6) in mango slurry fermented by different LAB, the D-limonene concentration was 7.8-10 times higher compared to the concentration in the unfermented slurry, where in yeast fermentation, the D-limonene concentration was 2.2 to 4.5 times lower compared to the concentration in the unfermented juice [41]; (7) in pomergnate juice fermented by _L. plantarum_ strains, the D-limonene concentration was increased compared to the concentration in the unfermented juice [24]; and (8) in tomato juice fermented by _L. casei_, D-limonene was detected, where it was not detected after fermentation by _L. plantarum_ or in the unfermented juice [32]. However, the D-limonene concentration was reduced in 2 studies after fermentation: (1) The D-limonene concentration in a distillate prepared using simple distillation from _L. rhamns_ fermented orange pomace was 2.3 \(\upmu\)g/mL, compared to 4.8 \(\upmu\)g/mL in the unfermented pomace distillate, where it was not detected in distillates prepared using simple distillation. In the same study, using simple distillation, in a distillate of melon by-product fermented by _L. rhamns_, the \(\upalpha\)-terpineol concentration was 2.0 \(\upmu\)g/mL, compared to 1.0 \(\upmu\)g/mL in the unfermented melon by-product distillate. Whereas using vacuum distillation, the \(\upalpha\)-terpineol concentration was slightly increased to 0.25 \(\upmu\)g/mL in the distillate from the fermented melon by-product, compared to 0.18 \(\upmu\)g/mL in the unfermented melon by-product distillate [44]; (2) in kiwifruit juice (Hongyang and Xuxiang cultivars), Hongyang cultivar juice fermented by either _L. acidophilus_, _L. heleticus_, or _L.