The Effect of Inert Pressing on Juice and Wine Chemical Profiles in Marlborough Sauvignon blanc

Abstract

New Zealand Marlborough Sauvignon blanc is well established within the wine industry for the distinct aroma profile of gooseberry, passionfruit and green capsicum. This project focuses on hyper – reductive winemaking on a commercial scale, and aims to analyse the difference in aroma compounds obtained involving the use of an inert press and a conventional press. At the pressing stage exposure to oxygen is particularly high; the use of inert gases to generate an inert environment allows grapes to be pressed in a reductive environment preventing oxidative processes. These oxidation reactions can result in generation of off-odours that are detrimental to the quality of the wine. ANOVA (analysis of variance) and Tukey HSD results showed increased concentrations of varietal thiols 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) in finished wines where an inert pressing system was applied and oxygen exposure was limited during the pressing cycle. Hyper-reductive handling also seemed to increase other reductive compounds such as dimethyl sulfide (DMS) and increased concentrations in polyphenols. This experiment gave some valuable insight of the use of an inert press as a tool to aid in the enhancement of varietal thiols 3MH and 3MHA and prolonging the possible shelf-life of Sauvignon blanc. Keywords: aroma compounds, DMS, GC/MS, HS-SPME, hyper-reductive winemaking, inert press, Marlborough Sauvignon blanc, varietal thiols