South Africa Wine Research Projects

3. OENOLOGY RESEARCH PROJECT IN PROGRESS

REDUCING OXYGEN AND SULPHUR DIOXIDE IN WINE PROGRAMME

SAGWRI WDT 23-01 Prof Wessel du Toit, South African Grape and Wine Research Institute, Stellenbosch University Start date: 2023

AIM AND INDUSTRY RELEVANCE: There is a worldwide move to reduce SO 2 in wines, which has also been identified as an area of interest by SA Wine. However, no suitable replacement for SO 2 , 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 SO 2 . The effect of lowering SO 2 levels in combination with reductive winemaking on the chemical and sensory composition of wines over time thus requires attention. Previous research at the Department of Viticulture and Oenology has shown that nitrogen sparging can reduce oxygen levels in wine to induce a reductive environment without drastically changing the chemical composition. An arbitrary approach to sparging in commercial wineries has been observed as part of this investigation. 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 SO 2 wines to be produced. However, such a commercial sinter can play a dual role by allowing oxygen to be added during fermentations to prevent the formation of reductive com pounds 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.

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SOUTH AFRICA WINE RESEARCH 2024