Photo by: Denise M. Gardner
A winemaker’s desire to produce a deeply colored, concentrated red wine can be a strong driving force behind winemaking operational decisions. Processes like cold soak, extended maceration, or even the use of saignée become the norm when winemakers hear other winemakers employ these techniques to enhance red wine color.
But sometimes our use of a winemaking process does not provide us with the result we were hoping for. How can that be?
Know Thy Grapes
One of the key messages I think winemakers need to hear is that grapes sourced from various parts of the world can ultimately result in very different wines. These differences can be found in taste, but also within chemistry, in which things like color are included.
Red Vitis vinifera wine grape varieties (e.g., Cabernet Sauvignon, Merlot, Cabernet Franc) produced in the western part of the U.S. (i.e., California, Oregon, and Washington) are likely to carry higher concentrations of phenolics compared to the same varieties grown in the eastern parts of the U.S. This is based on research findings that indicated a lower phenolic concentration of red grapes grown in New York state versus California (Martinson and Sacks, 2019). While we do not have a library of phenolic data for grapes produced across the continental U.S., one can currently assume that grapes grown in regions with lesser warm, dry days than the norm in the Western U.S. are likely going to follow a phenolic concentration pattern that is similar to that found in New York grapes. Of course, exceptions may arise, but we simply do not have that data available to us yet to make strict conclusions on phenolic concentrations in many winemaking regions outside of the Western states.
The lesser concentration of phenolics means two things:
- there are less color pigments (anthocyanins) available for extraction pre- and during fermentation, and
- there are less phenolics (tannins) available for stabilizing red wine color.
Furthermore, many grape growing regions are experiencing high potassium retention in grape clusters. I have previously talked about the challenges associated with high potassium retention here and here. (Author’s Note: The Wines & Vines article takes a bit of time to load.) One of the primary challenges with potassium retention is that it buffers the pH, causing the pH of wine to increase. This increase in pH makes red wine color retention and stabilization more difficult for winemakers.
Winemaking Processes that Affect Red Wine Color
Beyond the challenges associated with changes in grape (and hence, wine) chemistry based on growing region, many winemakers overestimate the benefits associated with red winemaking techniques and processes. How often do you hear winemakers say they “cold soak “x” variety for “y number of” days to enhance red wine color”?
But does the cold soak process enhance red wine color? Does the winemaker have a ‘control’ batch of the same wine for direct comparison? In many cases, this is not practical, but it also means that it is easy to reach false conclusions.
If red wine color is influenced, how did it change? Was the color more intense? Did the color hue change?
And does the process highlighted work on every red wine grape variety?
Below, I explain a few details about red winemaking techniques to clarify common misconceptions associated with “enhancing” red wine color.
Chemical processes that affect red wine color
Wine grapes have predetermined concentrations of both red color pigments and tannins available at the time of harvest. Tannins, specifically, are necessary for the stabilization of the red wine color pigments. Furthermore, tannins can play a role in wine sensory, including the perception of astringency, bitterness, and mouthfeel.
While the concentrations of these phenolics is predetermined in the fruit chemistry, winemakers may have some control in altering the concentrations of these substrates through winemaking operations that extract, stabilize, and/or concentrate those substrates:
- Increasing extraction of substrates associated with red wine color. This includes anthocyanin (red color pigments) and tannin (stabilizing components) extraction. [Note: in some literature you may find the terms anthocyanins and tannins combined in the term “phenolics,” as they are all phenolic compounds.] Extraction techniques include the winemaking processes cold soak (for both anthocyanin and tannin extraction), thermovinification, and extended maceration (for tannin extraction).
- Improving stabilization of the red wine color substrates. These processes facilitate shifting the chemical equilibrium in favor of red color pigments forming more stable chemical complexes that are less influenced by things like sulfur dioxide additions. Stabilization techniques include the winemaking processes micro-oxidation (micro-ox) and delayed malolactic fermentations.
- Concentrating red wine color. Concentration techniques are often used to provide concentration of several chemical components, including red wine color compounds. Sometimes these techniques have a profound influence on the wine’s flavor and style. Other chemical factors that are influenced by concentration techniques include aroma/flavor components, tannins, acids, sugars, and additional soluble chemical components. Concentration techniques include the winemaking processes saignée (bleeding free run juice off of red must pre-fermentation), thermovinification, and Appassimento-like methods (drying out grapes prior to fermentation).
Choosing color-driven winemaking processes
While it’s possible that a winemaking technique may influence more than one chemical process related to red wine color stability, many techniques favor one of the three processes: extraction, stabilization, or concentration.
This is important to understand from a winemaking perspective as a certain winemaking technique may be more appropriate to use in a specific situation. The winemaking technique should make sense for the wine being made. Techniques should be selected based on the wine grape variety, growing season, production capabilities, and goals of the winemaker.
For example, a red hybrid wine grape variety may not benefit from enhanced extraction techniques, as red color pigments are often available in excess and tannin substrates are difficult to maintain due to the naturally high protein levels in red hybrids. Thus, putting wine grapes through extraction-focused processing operations may not be beneficial for that particular wine.
Another example includes enhanced stabilization techniques. Stabilization studies focused on delayed malolactic fermentation are often used on Pinot Noir varietal wines, a variety that is naturally lacking in color intensity. For a wine variety like Cabernet Sauvignon or Malbec, these techniques may not be as necessary given the relative natural color intensity associated with the varieties. Other stabilization techniques, like the use of micro-ox, may be beneficial for many winemaking varieties. However, recommendations for use may be based on Western U.S. wine chemistries so considerations should be made when using micro-ox on Midwestern or Eastern U.S. wines as the chemistries, and, thus, results can vary.
Do you need more help with enhancing red wine color in your wines?
Choosing the right red winemaking techniques for your wines can be tricky. It may also require a few years of trial and error to see what actually works for your operation.
Denise Gardner Winemaking offers the Production Guide: Red Wine Processing Techniques to Enhance Red Wine Color to both DGW Members and Clients, which summarizes many of the wine processes mentioned above. This Production Guide acts as a quick reference to the purpose of each process and general tips on using that technique properly during production.
For more information on how to access this and other Premium Content resources on the DGW website, please refer to the Membership Services page available to the winemaking community. Any questions can be directed to info@dgwinemaking.com.
Resources
Gardner, D. July 2017. Coping with High-pH Wines: Addressing high-potassium concentrations in the fruit during winemaking operations. Wines & Vines. Available at: https://winesvinesanalytics.com/features/article/186363/Coping-with-High-pH-Wines
Gardner, D. September 23, 2016. Making [red] wine from fruit high in potassium. Penn State Extension Wine & Grapes U. Blog. Available at: https://psuwineandgrapes.wordpress.com/2016/09/23/making-red-wine-from-fruit-high-in-potassium/
Martinson, T. and Sacks, G. 2019. Flavor Challenges of Breeding Disease-Resistant Grapes Using North American Vitis spp. Appellation Cornell, 2019-4. Available at: https://grapesandwine.cals.cornell.edu/sites/grapesandwine.cals.cornell.edu/files/shared/Research%20Focus2019-4%20Final2.pdf
