Wine Color Over Time
The following text and photos are contributed by Flying Goat Cellars Ambassador Faye Walker:
Follow the rainbow
At Flying Goat, we pride ourselves on age-worthy wine. While most wineries throughout Santa Barbara County offer selections as recent as 2022, walking into our Lompoc tasting room brings visitors face-to-face with vintages from 2014 to 2019. Tasting flights consequently encompass a range of wines from various years and vineyards. And for those seeking out a deeper sensory experience, bottles as far back as 2000 lie in wait amongst the library wines.How are these Pinot Noirs evolving during the passage of time? Barrel aging and bottle aging are both important to the development, softening and smoothing of the end result. In addition to the taste, the color density and hue of the liquid takes on different characteristics. The nature of wine color is complex because there are many interacting components; at the core of the matter, our winemaker's gradations of Pinot Noir bring just the right amount of color to our world.
Phenols
Several chemical mechanisms are key players in the transition of red wine from a young (typically more red-purple) to aged (usually taking on tones of orange, brown, and garnet). The biggest hitters? Aromatic compounds called phenols.
Phenolic compounds all have a phenol ring incorporated into their chemical structure. Their various forms are found in flowers, fruits, and vegetables throughout the animal kingdom. Besides color, wine owes much of its structural development to a diverse array of chemical reactions involving phenols.
Flavonoids
In the phenols within grapes and wines, there are two main categories: flavonoids and non-flavonoids. The former all contain a three-ring backbone structure, while the latter is a catch-all category for smaller molecules that lack the rings.
If you've heard of tannins, then you're already familiar with flavonoids. Red wine gets most of its characteristic pigmentation from flavonoids inherent to the skin and seeds of grapes. While flavonoids also exist in white wine, the levels are ten times higher in red wine—to the tune of nearly 4 g of the compounds in each liter. Non-flavonoids, such as the antioxidant resveratrol, originate in the fleshy pulp of grapes and account for 80% of the total phenolics found in white wine.
Anthocyanin
One flavonoid in particular is paramount to the color of red wine: anthocyanin. Stemming from the Greek words for 'dark blue' and 'flower,' these pigments brighten everything from cauliflower to pansies with red, blue, and purple. In the context of wine, six different anthocyanin analogues each lend their unique hue of red-purple to the composite color.
So where does aging factor into the picture? The answer lies in the fact that anthocyanins are actually unstable. Because of their ability to react with tannins and other compounds, anthocyanins can link onto molecules to gain stability. Newer wines will therefore start off with more free anthocyanins; then, those anthocyanins become bonded and stabilized over time. The bound molecules are no longer suspended in the liquid, and their loss leads to a decrease in color intensity.
At the end of the arc
At the same time, many other side reactors and behaviors are concurrently affecting red wine's color over time. Everything from the pH to the oxygen content to the presence of sulfites will change the shape and structure of anthocyanins and their derivatives. The shifting dynamics in a single bottle of pinot can never quite be predicted by scientific research. With that being said, now will always be the right time to crack open a bottle of our age-worthy wines!
Sources and Further Reading:
GuildSomm. "A Guide to Wine Phenolics." https://www.guildsomm.com/public_content/features/articles/b/jennifer-angelosante/posts/phenolics
Waterhouse, A. L. et al. Understanding Wine Chemistry. "Non-Flavonoid Phenolics." https://onlinelibrary.wiley.com/doi/10.1002/9781118730720.ch13
Wikipedia. "Flavonoid." https://en.wikipedia.org/wiki/Flavonoid
Wikipedia. "Phenol." https://en.wikipedia.org/wiki/Phenol