Impact of glutathione and elemental sulphur juice addition on the volatile thiol production in South African Sauvignon blanc wine
Abstract
Volatile thiols play an important role in Sauvignon blanc wines worldwide, they can have either positive or negative organoleptic properties. Three compounds, 3-mercaptohexanol (3MH), 3-mercaptohexyl-acetate (3MHA) and 4-mercapto-4-methylpentan-2-one (4MMP), also known as varietal thiols, have been identified to contribute positively to wine aroma and are responsible for the distinct gooseberry, grapefruit, guava and box tree character found in Sauvignon blanc wines. Certain volatile thiol compounds though, can cause off-aromas of onion, garlic, rubber and rotten egg, this group of molecules is known as reductive sulphur compounds (RSC). This study looks into how the addition of sulphur-compounds to Sauvignon blanc juice contributes to the varietal thiol (3MH and 3MHA) concentration and reductive sulphur compound concentration in South African Sauvignon blanc wine. Glutathione (GSH) and elemental sulphur were tested in two different Sauvignon blanc juices. The compounds were added to the juices in two different concentrations (1.5 and 3mg/L elemental sulphur equivalent) before yeast inoculation. The standard winemaking protocol was followed and after fermentation the varietal thiols as well as the reductive sulphur compounds were tested. The addition of GSH and elemental sulphur did not have an influence on the production of varietal thiols. Some differences were seen for the reductive sulphur compounds, but these cannot be explained by the addition of either GSH or elemental sulphur. This study shows that the addition of glutathione to Sauvignon blanc juice did not influence the production of varietal thiols nor did it contribute to the production of reductive sulphur compounds under our conditions.
Issue: Macrowine 2016
Type: Poster
Authors
*Stellenbosch University