Sulfur Dioxide Management during Aging Is an Important Factor for the Development of Rosé Wine Color

Abstract

Summary Goals: The goal of this project was to determine the impact of sulfur dioxide (SO 2 ) and berry maturity on the color of Syrah rose wines through fermentation and accelerated aging. This project also set out to determine the best method for measuring potential color of rose wines by measuring anthocyanin bound to SO 2 . Key Findings: Acetaldehyde was found to be the most suitable reagent for reacting with SO 2 bound to anthocyanin and releasing “potential color” of rose wines. Color in rose wines was affected by fruit maturity and decreased during fermentation. SO 2 treatment had no impact on rose color by the end of fermentation. During aging, absorbance at 520 nm increased over time and was affected by fruit maturity and SO 2 treatment. Final absorbance at 520 nm after eight weeks of accelerated aging was accurately predicted by a reaction with acetaldehyde prior to aging. When analyzed with tristimulus color measurements, fruit maturity and SO 2 content affected visual intensity of red and yellow hue over time. Impact and Significance: This study provides winemakers with tools to measure apparent and potential color in rose wines. In both 22 and 24 Brix fruit, wines retained only 38 and 27%, respectively, of the initial color by the end of fermentation. The level of SO 2 added to wine had no impact on postfermentation color, but levels of SO 2 added prior to aging did impact long-term color. The potential for a rose wine to darken over time was influenced by how much color the wine initially had, and SO 2 concentrations had a larger impact on color development in wines with more color initially.