SAGWRI WDT 23-01
Reducing oxygen and sulphur dioxide in wine programme
Prof Wessel du Toit
South African Grape and Wine Research Institute (SAGWRI), Department of Viticulture and Oenology, Stellenbosch University
There is a worldwide move to reduce SO2 in wines, which has also been identified as an area of interest by Winetech. However, no suitable replacement for SO2, especially in terms of its dual antioxidant and antimicrobial capacity, has been found yet. Ascorbic acid can remove oxygen from wine but requires the presence of SO2. The effect of lowering SO2 levels in combination with reductive winemaking on the chemical and sensory composition of wines over time thus requires attention.
Previous research at the DVO has shown the potential of nitrogen sparging to reduce oxygen levels in wine to induce a reductive environment without drastically changing the chemical composition. As part of this investigation, an arbitrary approach to sparging in commercial wineries has been observed. It is also the case that commercially available sparging sinters are expensive. The need thus exists to develop a commercial sinter that is more effective in removing oxygen, saving on inert gas costs while still being affordable. This could also allow for lower SO2 wines to be produced. However, such a commercial sinter can play a dual role by allowing for oxygen to be added during fermentations to prevent the formation of reductive compounds and induce polyphenol polymerisation in red wines.
The ultimate goal of this project is to design, manufacture and test a prototype sparger for gas removal during wine production.