Effect of glutathione and inactive yeast additions to sauvignon blanc at harvest on wine aroma

Abstract

Marlborough is the largest wine-producing region in New Zealand, and 72% of the country´s grapes were produced in this region in 2014. Sauvignon blanc is the most widely planted variety and also the most important one in terms of volume, while some other varieties such as Pinot Noir, Chardonnay, Pinot gris and Riesling can be found in the region. New Zealand Sauvignon blanc is quite distinctive compared to other Sauvignon blanc wines from around the world, with strong tropical and passion fruit aromas, due to the high concentration of varietal thiols such as 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA). The aim of this study was to quantify the aroma compounds in wines made from juices treated with five antioxidant mixtures at harvest (control, SO2/Glutathione, Glutathione, SO2/Optiwhite® and SO2/OptiMUM White®). There was a significant difference in the concentration of the varietal thiols (3MH and 3MHA) in the wines produced from juices treated with SO2/Glutathione. The concentration of 3MHA was three times higher in the wines treated with this mixture than in wines produced from juices to which only SO2 had been added. On the other hand, the concentration of hexanol in juice and wines increased in the samples treated with glutathione; the same effect was observed with the polyphenols catechin and the Grape Reaction Product. There were no consistent effects on other aroma compounds such as esters, fatty acids, norisoprenoids, terpenes and alcohols, and varying impacts were seen across the different sites. Keywords: Marlborough Sauvignon blanc, antioxidant additions, sulfur dioxide, glutathione, Optiwhite®, OptiMUM White®, aroma compounds, GC-MS, SPME, ANOVA.