Ever open a bottle of red wine you’ve lovingly saved for 20 years only to be disappointed as a brick-orange liquid followed by a brownish sludge falls into your glass?
The issue of color optimization and retention in red wines is a large and complicated one — I could probably write at least ten articles on the topic. The colored matter in almost all grapes is contained only in the skin, though the green or yellowish flesh can contain important color precursors and elements important to color retention like natural acids. The most basic thing to know is that some red grape varieties tend to have more or less color components and color precursors than others. Cabernet Sauvignon, for example, tends to have more (and more stable) color than Pinot Noir. So the first thing to contend with, whatever your grape or must chemistry, is the grape variety itself. In my experience the following grapes tend to have color-retention problems: Pinot Noir, Sangiovese, Tempranillo, Nebbiolo, and many hybrid varieties. Safer color-retaining bets include Syrah, Cabernet Sauvignon, Petit Verdot, Malbec, and Petite Sirah. Of course, if you really want to maximize color, you could try making red wine (or at least a small amount as a blender) from grapes of which the flesh is also red; Alicante Bouschet is often grown by large wineries just for that purpose. Be aware, however, that Alicante, at least in my experience, doesn’t produce the most charming table wines and is best used only as a blender. As you can see, your choice of initial grape really matters.
There are many things that can be done every step of the way in red winemaking to make the most of what Mother Nature has given your grapes. Be mindful that oxidation, whether microbial (metabolically), chemical (directly reacting with environmental oxygen), or enzymatic can degrade color and cause less than optimal conditions for the survival of colored compounds. My tips for optimizing and retaining maximum color in red musts and wine include:
• Pick before the grapes become overripe and raisined. This is more of an anecdotal tip from my 15 years making wine, but older, shriveled grapes, when made into wine, have many of their aroma and color compounds “pre-aged” by the sun and chemical breakdown. Additionally, acidity is lower, yeast nutrients depleted, and a host of microbes (yeast, mold, bacteria) may begin to grow on the grapes surface, not exactly conditions conducive to optimal winemaking.
• Minimize the time between field and fermenter. Oxidative and spoilage microbes can grow the longer the lag between picking and processing.
• Correct high pH (low acid) musts promptly. For red wines that will go through malolactic fermentations (which de-acidifies the must), I like to see initial pH no higher than 3.60. When in doubt, and if you lack equipment, if the must tastes at all like it lacks acid, I recommend adding 1 g/L before pitching yeast. Mix well. High pH conditions encourage spoilage microbe growth as well as make highly pigmented color compounds less stable.
• Ferment on a tannin or oak product to provide “sacrificial tannins.” You can try to bolster the amount of color you’ll be left with post-fermentation if you can provide your red ferment with additional tannin for oxygen to attack instead.Most home winemaking retailers sell an array of fermentation tannins for red wine.
• Use a fermentation enzyme specifically for color optimization. These are usually added after crushing and before pitching yeast. These enzymes help lyse the cell walls of the grape skins, releasing colored material and color precursor elements into the fermenting must. Always be careful of adding an enzyme too close to or too soon before or after an SO2 addition as an enzyme’s reactivity will be decreased by sulfur dioxide.
• During fermentation, punch down, pump over, or otherwise mix and agitate your must at least twice a day. Perhaps three times during the peak fermentation days.
• Ensure a healthy and complete fermentation. This means keeping pH, fermentation temperatures, and must nutrition within healthy ranges.
• Keep the wine on the skins for sufficient days. I usually press at dryness or a few days afterwards, with a 10–12 day fermentation being usual. If you have a quick, short fermentation (4 days or so) you may want to leave the wine on the skins a few more days to make sure you’re extracting enough color, making sure to keep stirring to minimize oxidative/microbial spoilage risks.
• Avoid oxygen during aging. Oxidation can turn pigments orange or brick red and encourage their precipitation. Keep containers topped up.
• Maintain adequate levels of free SO2 to serve as an antioxidant. Typically shoot for 30 ppm, but more if you have a high pH situation.
• Store wine away from light and heat. Light can affect color, so also don’t use clear bottles. Wine is ideally stored around 50–55 °F (10–13 °C). Warmer temperatures will speed up the condensation and oxidation of colored compounds.