Anthocyanins and Wine Color
The Role of Anthocyanins in Wine Color
In the past, it was widely accepted that anthocyanins were the primary contributors to the color in wine. To a large degree that is still true, but like everything else in nature, it is not that simple. There are a multitude of other molecules and compounds that interact with anthocyanins to affect wine color.
The three elements that are thought to affect a wine’s color the most are; anthocyanin concentration, co-factor concentration (compounds that bind with anthoncyanins) and polymeric pigments.
The phenomenon of Hyperchomicity allows for more visible red color than anthocyanins alone. This happens when cofactors or polymeric pigments bind with the anthocyanins, creating more color than unbound pigments alone.
Recent research into anthocyanins and the color of wine focuses on the interaction and concentration of cofactors. This gets even more complicated because the type and concentration of cofactors changes by varietal, location, climatic conditions, soil pH, nutrient availability, temperature and season.
High acidity increases the proportion of anthocyanins in the flavylium state, making the color a more vibrant red. As the acidity of a wine decreases, the percentage of flavylium anthocyanins decreases. At a pH of 3.5 (high acidity) around 25% of anthocyanins are in the flavylium state. As the pH increases to 4.0 (low acidity), only 10% of anthocyanins are in the flavylium state.
Although acidity plays a huge role in color, sulfur dioxide is even more important. When it reacts with anthocyanins, it effectively bleaches them, taking away their color.