VintageTexas Sunday “Cyclopedia of Wine: Cold Soak versus Extended Maceration
Maceration is a winemaking process whereby the phenolic materials of the grape (tannins, coloring agents (anthocyanins) and many flavor/aroma compounds) are extracted from the grape skins, seeds and stems into the must (pulpy juice of the grape). Since most of the pigments in red grapes are in the skins, maceration is the principal technique used to yield the dark purple-red color in red wines.
Pre-fermentation cold soak has gained popularity as a trendy winemaking technique in recent years. It seems to have started as way to get more color and flavor from the finicky and notably thin-skinned grape, Pinot Noir. The technique has now been used on just about every red grape in the known wine world.
Cold soaks on macerated grapes are typically conducted at temperatures of about 40 to 50 F for periods from a couple days to about a week, but under the hand of an experienced winemaker, they can run as long as two weeks. The use of low temperature in this process is to reduce bacterial growth and spoilage in the presence of oxygen due to the absence of the protective carbon dioxide gas formed during fermentation. Arguments continue as to the true benefits of cold soaking, which red grape varieties truly benefit, and the optimum period for cold soaking. It does appear that “thin-skinned” varieties of grapes and those that do not give color and aroma readily stand to benefit more than those that have thicker, color-rich skins. In Texas, I would think that Sangiovese and Grenache are good candidates for the cold soak, as may be Black Spanish which does not have a lot of tannin to give.
During conventional red wine fermentation, the grape skins and solids are also being leached of color, tannins and aromas. Typically, when fermentation is done, the wine is pressed or drained from the solids, but if a winemaker wants to extract more from the grape solids (skins, seeds and stems), the process used is extended (alcoholic) maceration.
Why do it? Some winemakers like the added color and flavor and feel that it improves a wine’s overall mouthfeel and that it might even improve the ageability of the wine. Sometimes, more color can be extracted during post-fermentation extended maceration as a result of the increased solubility of color-containing molecules from the skins in the presence of alcohol. Another factor in extended maceration is that short chain tannin molecules can link up to form longer chain molecules that yield more supple and pleasurable wines.
However, just as with pre-fermentation cold soaking, with extended maceration, experience is the rule to follow. Empirical studies show that extended maceration can make wines that are more complex and delicious, but sometimes if taken to extreme can result in overly astringent and harsh tannins, which may not benefit from aging in barrel or bottle. This process is often done with Bordeaux and Rhône grape varieties that have significant tannin levels. However, there is typically some loss of fruitiness and color in the process, but many feel it is justified by the complexity and mouthfeel that it adds to the wine.
In Texas, I’ve noticed that what I sensed was an unwillingness on the part of some Texas winemakers to try to extract all that the grapes have to give. I think that this is because they fear loosing what precious few Texas grapes they have to what on their part may be an untried process, at least on their part.
While on a visit to wineries in the Piemonte (Piedmont) region of northern Italy that make inky (and ageworthy) Barolo from locally grown Nebbiolo grapes, it was obvious to see that winemakers there had no such fear and took all they could from the grapes with hugely long extended macerations. They also had innovative techniques like rotary fermenters that were used to mix the “brew” for a month if not longer. At the end of the process, the skins were a pale shade of gray…no pigment was left in them.
So, are cold soaking and extended maceration important to making wine in Texas? I think so, as we need wines of body, character and complexity to represent the Lone Star State as we enter the global wine world.
Next time you visit a Texas winery, try to find someone that works with the wines on the production floor. Ask them about cold soaks and extended maceration. I’ll bet that you’ll get one of many possible responses based on the varieties of grapes they use, their willingness to explore the unknown, and the experience of the winemaker with these processes.
Russ great post…need to make sure we don’t get hung up on color (provided by rotary) and other things just for their own sake. What we are looking is quality, right? La Spinetta and Marcarini are both quality producers but with a completely different style! We need to make sure that Texas has many styles of high quality wine. Then we all win!
Drew,
Good comment and from a good perspective. I just get the feeling like too many Texas winemakers stay within their comfort zone. I’ve sampled many Texas wines that have great aromatic qualities, but seem thin to me. I’ve looked at the extracted and pressed-off skins which seem to have more to give.
Maybe we just need more Texas grapes that will give the winemakers the courage to “explore”.
Thanks for providing your response to this blog. I think it’s an important topic.
See you at Texsom (http://www.texsom.com) or before.
Russ
I just found your site. Thanks for that informative article. I am new to the intricacies of grape growing and wine making. Alas, I am merely a consumer at this stage in my life. However, the more I learn about what makes a particular wine the way it is, the more rich my enjoyment of the wine. I’ll keep reading your site. I was born in Fort Worth and love that Texas has a burgeoning wine making industry. I buy Texas wines regularly on principle. I’ve been pleased more often than disappointed with those I’ve tasted.
Russ- completely agree would like to see more body and color in many TX wines! Just want to make sure we are doing it for the “right” reasons.
Drew, Russ, very interesting subject, here is my point of view on the issues/reasons why we do not see too much extended maceration/cold soak, I don’t have as much Texas winemaking as some others but after having seen a few vintages Texas now (Mostly High Plains fruit), here is my view.
The main winemaking issue is that we “leach” Potassium for as long as the skins are in contact with the juice, that means our PH is going higher and higher (it already started really high PH due to our warm weather) and the higher the PH the more issues we have:
– High PH actually “bleach” anthocyanin and lowers perceivable color (even though it’s there)
– High PH means higher sulfite additions to protect the wine (bleaches color)
– High PH means wine that turns wine flaws much more easily
Short vatting time is actually recommended for warm weather winemaking to lower Volatile Acidity risk, I don’t like it either but that’s actually a conscious classroom recommendation.
Now onto the wine color subject, color intensity peaks at 8-10 days of vatting no matter if there is cold maceration (Riberau-Gayon, Handbook of Enology) and then will slightly decrease until we press the wine.
Based on that idea people starting using rotary fermenters, they knew they only had 8-10 days max to extract the color and the rotary will make sure you take it all (and maybe a little too much tannins in the process)
Now, we do use Cold Soak and Extended maceration for our CALAIS wines, not on all wines, we’ll make a decision based on chemistry analysis and taste. We ran up to 25 days last year on Newsom Tempranillo, the result is beautiful in terms of finesse/complexity but we have to stay on top of these barrels (top up every week …)
Did I ever mention that winemakers in cold weather regions have it easy ?
Good comments all around, Ben. One question….
Is the potassium issue a result of our limey soils, hot climate or both? or just that with longer vatting time, it just comes out?
When you decide to due CS/EM is it plainly based on pH or in combination with other parameter?
Russ
We CS everything for red wine since we usually crush directly in the vineyard, EM really depends on taste and if we feel the wine will be better after than it is before. When you start to do extended maceration you just have to keep going you cannot stop in the middle or you will have really harsh tannins. At some point the tannins softens up, that’s when we go to press it.
For the potassium issue, based on the soil samples/petiole analysis I have seen, I would say hot climate is probably the main driver (acid respiration), soil samples I have seen on that vineyard are perfectly balanced (aka they know what they’re doing), they don’t water much either (RDI), but we still end up with really high PH.
You can make really good wines at high PH, you just have to be very careful with them …
During my stint in Texas making wine, I noticed that most winemakers in Texas made pre-ferment acid adjustments with a very light hand, if at all. With great software available (Kelly Wheat’s IWS Predictive Acid Modeling, etc), I’m really not sure why, outside of the anti-interventionist set, Texas wine isn’t made safer PRIOR to CS and primary fermentation. These modern tools allow you to set a desired ends and (using a considerable amount of analysis) adjust the means by which you achieve them. Lower pH allows for a more thorough phenolic extraction, lower SO2 additions, and contributes to the selective pressure of S. cerevisiae against competing bacterial and yeast strains. The modeling has become so accurate that it can account for high [K+] musts and its effect on tartrate equilibria. As long as the adjustments don’t swing the must pH to <3.5 and the sulfite additions aren't done in irresponsible amounts (both too high OR too low), the rest of red elevage should proceed unencumbered and more safely than it would have sans acid addition.
I've forgotten how quickly Texas vineyards begin to show the first chemical signs of dormancy in Texas ([K+] goes up, [H-Tartrate] goes down), but I would guess that if you have problems with K+ leeching, you're pushing harvest into the first signs of dormancy. I know there is an issue with achieving sugar and phenolic ripeness prior to potassium salts being pumped into the fruit in hot climate growing regions, but the increase in [K+] wrecks tartrate equilibria. This most likely accounts for your pH increase during CS (as tartaric acid equilibrium would trend, in part, toward Tartrate salts and fall out of solution). As I see it, you have two options:
1) Harvest earlier to ensure a safer pH and [K+] in which to make wine (risking a lack of sugar and phenolic ripeness).
2) Harvest later into phenolic and/or sugar ripeness and adjust acid appropriately to style (risking almost nothing except a small piece of potential marketing material).
As to EM, a recent report presented at the 2011 ASEV conference by Federico Casassa of the Harbetson Lab at WSU states that while flavonols and tannins increase in concentration significantly during EM, these differences recede to concentrations achieved by identical fruit that was processed without an EM phase. Color saturation was also observed to increase during EM, but also decreased to the same baseline post-pressing. These measurements were taken with wines of varying sugar concentrations, conveying a range of final ethanol concentrations (all to essentially the same result). The only somewhat appreciable change was seen in an increase in polymeric pigments in the EM wine compared to the non-EM sample (this conveys color stability).
With a nearly negligible result, the use of EM seems to be, at best, a risky procedure that could be achieved by various other means (FT Rouge and/or Opti-Red during primary, etc). Again, for those who claim that not mucking about with the fruit yields a better product, I could understand how this might not be palatable. But, you're growing grapes in a very marginal climate. This might help you not make marginal wine.
If that last comment seems to imply that Texas is making marginal wine, then I apologize. Intended no such statement.