# Volatile Composition of Fortification Grape Spirit and Port Wine: Where Do We Stand?
## 2 Douro Demarcated Region Characteristics  
Douro Demarcated Region (DDR, Figure 2) is the first demarcated and regulated region in the world, established in 1756. To ensure the superior quality of Port wine, in accordance with the Decree-Law No. 97 of 23 April 2012, the Instituto dos Vinhos do Douro e Porto (IVDP), founded in 1933, is the public body responsible for the certification, regulation of the production, and approval of the wines and the wine spirits produced in the Douro Demarcated Region. The IVDP guarantees the quality, authenticity, and the protection of the denomination of origin Douro and Port, by following specific criteria based on the soil, climate, and viticultural parameters [30]. Douro Demarcated Region extends over a total area of about 250,000 ha, with 43,167 ha of vineyards, of which 33,118 ha are intended for Port wine production, located on the steep hillsides along the course of the Douro River [5]. It is divided into three distinct subregions: Baixo Corgo, Alto Corgo, and Douro Superior (Figure 2A). The subregions of DDR are delimitated according to their edapholicmatic conditions and socio-economic factors. Baixo Corgo is part of the oldest viticultural area also known as _Alto-Douro Vinhateiro_, presenting the largest proportion covered with vines. The Baixo Corgo is associated with the most distinctive Port wines, and it is where the majority of the largest and most renowned _quintas_ (estates) are located. Douro Superior is the largest and the most recent expansion of the region, being the closest to the Spanish border and incorporated only in the 20 th century [7]. In terms of annual precipitation volume (Figure 2B), the rainfall decreases in the direction of the Spanish border, with the values varying between 400 mm (Douro Superior) and 1000 mm (Baixo Corgo). Sun exposure is a physiographic factor of great importance for the climatic characterization of any region, particularly the Douro Demarcated Region, since it provides a better understanding of the behavior of the vines in distinct situations. The northern margin of the river is under the influence of dry southerly winds, while the southern margin is exposed to the colder and wetter northerly winds and less sunshine. The air temperature is higher at the northern margin compared to the southern one (Figure 2C). The average annual temperatures range from 11.8 to 16.5 \({}^{\circ}\)C. The diurnal and annual temperatures are higher in Douro Superior compared to the Baixo Corgo, which can be explained by the distance from the sea [1; 32]. In terms of altitude, the region presents an average elevation of 443 m, ranging from 40 m to just above the 1400 m [33]. Douro valley has a mountainous topography dominated by schistose-layered rock with outcrops of granite, with moderated to steep slopes and diverse exposures (Figure 2D) [34]. Overall, this region is characterized by low precipitation, high temperatures and high radiation exposure, which contributes to water and thermal stress, specifically in the Cima Corgo and Douro Superior sub-regions [33]. Wine is produced in a limited geographic and climatic area, which might put wine grapes at severe risk from climate change and fluctuation. The most crucial elements affecting winegrape development and yield are drought and temperature [35]. By promoting different ripening profiles and accelerated cultivar growth, climate variations and fluctuations can have an impact on wine quality. Therefore, in warmer environments, grapevines reach their sugar ripeness earlier, and flavors do not develop accordingly, resulting in unbalanced wines with higher alcohol content and lower acidity [34; 35]. Projections indicate that further warming may range from 0.8-6.6 \({}^{\circ}\)C from 2020 to 2080, while precipitation during the growing season is projected to decline by up to 7-22% over the same period [35]. A shift toward warmer and drier conditions is foreseen in this region, which can impact the grape maturation and wine production [34].