Altitude, as an important factor in the expression of terroir, may affect wine quality. We evaluated the effect of altitude and its related climatic conditions on the phenolic characteristics and antioxidant activity of red wines made from grapes originating from high-altitude areas. The content of total phenolic compounds, total flavonoids and total anthocyanins increased with altitude in Merlot (ME) and Cabernet Sauvignon (CS) wines. Cabernet Sauvignon wines showed richer tannins with increasing altitude. Merlot and CS wines from higher altitude vineyards, showed a greater antioxidant capacity. Salicylic acid, syringic acid, caffeic acid, (+)-catechin, (−)-epicatechin, and the sum of individual phenolic compounds in the wines increased with altitude based on the results of HPLC. The scores of the sensory evaluation of ME wines increased with higher altitude. The highest score was determined for CS wine originating from 2 608 m. A clear grouping of wines according to grape cultivar and vineyard altitude was observed by principal component analysis. Regression analysis showed that altitude, followed by sunshine hours, made the greatest contribution to differences in the phenolic characteristics and antioxidant activity of red wines at different sites in a high-altitude region.
INTRODUCTIONEnvironmental factors such as light and field management practices have a combined effect on grapevine physiology and wine quality (Spayd et al., 2002;Feng et al., 2017). The French term "terroir" is used to define the geographical and environmental origin of grapes grown and harvested during a certain vintage (Deloire et al., 2008). This term includes all regional parameters, such as soil type, climate and orography (Douglas et al., 2001). Terroir is an important factor affecting grape and wine composition (Roullier-Gall et al., 2014).Altitude is usually considered an indirect control on the environmental conditions affecting plant metabolism (Kumar et al., 2006). Therefore, altitude may have a strong effect on climatic conditions that affect grape development and wine quality (Mateus et al., 2002). In particular, altitude gradient may reflect the integrated variation in temperature, humidity and solar radiation in a mountainous region with high vertical zonality (Zhang et al., 2005).Phenolic compounds contribute to a wine's organoleptic characteristics, such as mouthfeel and colour, and are associated with anti-cancer and cardiovascular protection and antioxidant activity (Burns et al., 2000;Skerget et al., 2004). The phenolic compound concentrations of grapes are affected by time of harvest and grape ripeness levels, thereby affecting the flavour and quality of the resulting wine. Phenolic compound concentrations are also affected by genotypes, viticultural practices and environmental conditions (Downey et al., 2006). Variation in phenolic characteristics of wine grapes has often been observed at different altitudes and also has been characterised by regional differences (Mateus et al., 2001(Mateus et al., , 2002Liang et al....