Influence of Sun Exposure on the Aromatic Composition of Chilean Muscat Grape Cultivars Moscatel de Alejandría and Moscatel rosada

The effect of sun exposure on the aromatic composition of two Muscat grape cultivars, Moscatel de Alejandría and Moscatel rosada, was monitored over two seasons. Fully exposed and artificially shaded clusters permitting 20% (shaded) and 50% (semi-shaded) sun exposure were used to assess the impact of shading in fruit aroma composition. Both cultivars contained similar levels of total free terpenols (2100 µg/L), although Moscatel de Alejandría was richer in total bound terpenols. The highest concentration of free terpenols was obtained from the semi-shaded treatment, although for Moscatel de Alejandría, the resulting difference between exposed and semi-shaded treated grapes was negligible. Shaded grapes had the lowest concentra- tion of terpenols, with poor Muscat typicity. The content of one of the most important terpenols from the aromatic perspective, linalool, appeared to be the most sensitive to sun exposure. Berry temperature appeared to be critical for maximizing monoterpene levels and muscat flavor in the fruit.