Summary
Goals: The goal of this project was to determine the impact of sulfur dioxide (SO2) and berry maturity on the color of Syrah rosé wines through fermentation and accelerated aging. This project also set out to determine the best method for measuring potential color of rosé wines by measuring anthocyanin bound to SO2.
Key Findings:
Acetaldehyde was found to be the most suitable reagent for reacting with SO2 bound to anthocyanin and releasing “potential color” of rosé wines.
Color in rosé wines was affected by fruit maturity and decreased during fermentation. SO2 treatment had no impact on rosé color by the end of fermentation.
During aging, absorbance at 520 nm increased over time and was affected by fruit maturity and SO2 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 SO2 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 rosé 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 SO2 added to wine had no impact on postfermentation color, but levels of SO2 added prior to aging did impact long-term color. The potential for a rosé wine to darken over time was influenced by how much color the wine initially had, and SO2 concentrations had a larger impact on color development in wines with more color initially.
- Received February 2017.
- Revision received August 2017.
- Accepted August 2017.
- Published online November 2017
- Copyright © 2017 by the American Society for Enology and Viticulture. All rights reserved.
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