The Impact of Enzymatic Oxidation of alpha-Linolenic Acid and Glutathione and Their Role as Possible Precursors to 3-Mercaptohexan-1-ol Formation in Sauvignon blanc.

摘要

Sauvignon blanc wines have become increasingly popular due to the diversity and range of aroma descriptors found, including green pepper, grassy, lime, and passion fruit. The aromas of Sauvignon blanc derive from volatile thiols, which are responsible for the characteristic aroma profile found in New Zealand style wines. This study explores the development of an important aromatic thiol, 3-mercaptohexan-1-ol (3MH), responsible for passion fruit and citrus aromas. The effect of different processing treatments on 3MH formation through the combination of controlled machine-harvesting simulation, micro-oxygenation, and supplemental additions was explored in order to determine the impact on aromatic potential of California Sauvignon blanc. This study utilized hand-harvested fruit, with an extended maceration after crush, to simulate some of the effects of machine harvesting, and the application of what are believed to be the important contributors to thiol formation. These contributors are a fatty acid, alpha-linolenic acid, and a naturally occurring antioxidant in grapes and wine, glutathione. This study explored the enzymatic oxidation pathway of alpha-linolenic acid to (E)-2-hexenal, which in the presence of glutathione will conjugate to the aldehyde, to form the known direct precursor to 3MH, 3-S-glutathionylhexan-1-ol (G3MH). Production and concentration of 3-mercaptohexan-1-ol (3MH) was determined by GC/MS in the finished wine through a collaboration with the University of Auckland. This study confirmed that the interaction of glutathione and alpha-linolenic generated a wine that showed a statistically significant increase in 3MH concentration.