## 3 Results and Discussion
### Further Discussion  
Dessert wines made from on-vine late-harvest or off-vine postharvest dehydrated grapes are widely produced in the world, including some wine regions of China. The evolution patterns of volatile compounds during the late- or post-harvest periods and the effects of this process on aromatic compounds in grapes or wines have been extensively studied, especially in the past decade. Among the published reports, most of them have focused on the grape materials for botrytized wine and icewine, or grapes that undergo post-harvest dehydration, while few studies have focused specifically on non-destructive on-vine dehydration processes. Therefore, the data presented in this article provide a clear picture of the evolution of grape volatiles during this process. For the quantitative analysis of grape aroma composition, as pointed out by [PERSON] et al. [10], the expression of the content for volatiles should be chosen appropriately according to the purpose of the study. However, some studies appeared to be somewhat haphazard in their choice regarding the expression and calculation of volatile content. In our results (Figure 3), the evolutionary patterns of volatiles during dehydration were completely different when represented in two separate ways, which strongly supported this viewpoint. When conducting similar research in the future, the expression of the volatile compounds content should be clarified first. For the readers, the same attention should also be paid when reviewing the literature. From this point of view, it is difficult to conclude whether the increases in grape volatiles (expressed in \(\mu\)g/L or other similar units) during dehydration or late-harvest in some articles could be attributed to the dehydration concentration effect or biotransformation. From the results of our study, it appears that the changes in volatiles during dehydration were the result of a combined effect of these factors. The most representative products of late-harvest wines are botrytized wine and icewine, both of which are made from over-ripe grapes that had dehydrated and underwent berry structure destruction, to some extent. _Botrytis cinerea_ infection is a specific and complex process that the grapes need to encounter--intentionally or unintentionally--during the late-harvest winemaking process. When the berry is infected by _Botrytis_, its cuticle is degraded by the mycelium, thus increasing its permeability, consequently leading to dehydration and wrinkling [10; 33]. After infection, _Botrytis_ alters the accumulation of grape secondary metabolites by inducing biotic and abiotic stress, or the defensive responses of the berry [47; 61]. The main metabolites associated with _Botrytis_ infection in grapes are 1-octen-3-ol, 4-terpineol, benzaldehyde, phenylacetaldehyde, furnaceol, 2-hepten-1-ol, 3,5-octaleni-2-one, sulcatol, vanillin, \(\gamma\)-butyrolactone, and \(\gamma\)-nonalactone, among others [32; 33; 34; 47; 62; 63]. In fact, _Botrytis_ infection is relatively common in icewine winemaking, and would result in modifications in the volatile composition of the grape and wine [21]. Of course, the role of the freeze-thaw cycle is irreplaceable in icewine-making, as this process leads to a series of biochemical and chemical reactions, including biotransformation, anaerobic metabolism, and oxidation, which produce significant changes in the volatiles of the berries, especially the C6 alcohols, higher alcohols, and oxidative terpene derivatives [19]. Based on our results, it appears that, although the grapes did not experience structural damage due to _Botrytis_ infection and/or freeze-thaw cycles, the concentration effect caused by water loss during this non-destructive dehydration was not the only factor responsible for the variation in the volatiles.