Effect of Training Systems on Viognier (Vitis vinifera L.) Grape and Wine Glycosides and Volatile Compounds

Abstract

Viognier (Vitis vinifera L.) grapes were grown in Northern Virginia for three seasons using three different training systems in a randomized complete block design consisting of Vertical Shoot Positioned (VSP), Smart Dyson (SD), and Geneva Double Curtain (GDC), and evaluated for the effects on grape and wine glycosides and volatile compounds. Fruit was harvested at the same Brix each season, and differences in berry weights were not observed. VSP-trained vines had the lowest crop load and lowest light levels in the fruit zone. Seventeen volatile compounds were analyzed using headspace solid-phase microextraction, GC-MS. Fruit showed differences in linalool, á-terpineol, â-damascenone, and n-hexanol concentrations among the training systems. Wines showed differences in both grape-derived and fermentation-derived volatiles. SD had the highest concentration for most of the free volatiles quantified in both the juice and wine. VSP had lower phenol-free wine glycosides all three seasons and lower phenol-free juice glycosides one season. Triangle difference sensory testing demonstrated differences between GDC and SD in wine aroma and flavor, and differences between VSP and SD in flavor, for two of three seasons.