Jul 032011
 

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.

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