Winetech Technical Yearbook 2022

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46 A RECENT STUDY INVESTIGATED VARIOUS SPARGING PARAMETERS AND ASSESSED THE EFFECTIVITY, WHILE MONITORING CERTAIN WINE CONSTITUENTS. BY CARIEN COETZEE, JAMES WALLS, STEVEN SUTTON & WESSEL DU TOIT I WINETECH TECHNICAL YEARBOOK 2022 INTRODUCTION Winemakers often use inert gas sparging to displace dissolved oxygen molecules in wine, thereby reducing the risk of oxidation. Even though sparging operations are regularly used in the cellar, there seems to be a lack of information regarding 1) parameters that can influence the efficacy of the sparging, and 2) the exact effects of sparging on the wine composition. It is generally believed that the sparging of wine with the goal of reducing the dissolved oxygen content will inadvertently “blow off” aroma compounds, thereby reducing the aromatic intensity and altering the sen sory perception of the wine. Theoretically, the volatile components can desorb into the gas during sparging in the same manner that dissolved gasses do, but the significance of potential losses needs to be qualified and quantified to assess if the effects have oenological importance. Researchers from the South African Grape and Wine Research Institute, Stellenbosch University (James Walls, Steven Sutton, Dr. Carien Coetzee and Prof. Wessel du Toit) conducted a Winetech-funded study to investigate the effect of certain variables, such as inert gas flow rate, gas composition, duration of sparg ing, number of sparging cycles, wine temperature and the utilisation of a diffusion stone (bubble size), while also assessing the influence of the different sparging regimes on the wine’s composition. The findings of this study were published in an MScAgric thesis in 2020 titled, Effect of oxygen management on white wine composition by James Walls. 1 The main findings from this study will be reported in this two-part article. Factors affecting sparging efficiency (PART 1)

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