Aging Wine

08/12/5

The French use the term élévage to refer to the aging/storage period in a wine's life.  It roughly equates to our term “to raise” in English, as in raising a child. An appropriate term, since our job as winemakers during this stage is to watch over the wine while providing the care and proper environment needed for it to have the best chance of developing positively. Aging/storage is made up of three parts: letting the wine continue to work on its own, monitoring its progress both chemically (by testing) and sensorally (by tasting), and carrying out a series of rackings for clarification as needed. Each of these three elements works together as a complete system that allows us to help keep the wine safe as it continues its maturation. Throughout this period, winemakers will need to properly maintain the SO2 levels, hold the temperature at a constant 55-60°F, and taste the wine every 4-6 weeks to monitor its evolution.  

 

Note: If you are working with barrels, you need to maintain the humidity at around 65-75% as well as top-up the barrels each time they are tasted.  

For complete information on working with barrels, see our MoreWine! Guide to the Use and Care of Oak Barrels online.

 

 
Understanding Polymerization and the need to remain vigilant

Even though we are doing very little “hands-on” work, as compared to the previous steps of crushing, fermenting and pressing, remember that wine is never static. It is always moving, shifting, and alive; and it continues to develop throughout the entire aging/storage period whether we are involved or not. At work is a phenomenon called polymerization.  Essentially the process of smaller molecules connecting up to create larger ones, polymerization creates more complex flavor, aroma, and structure.    While we have all heard that complexity is good in a wine, realize that just because a wine gains in complexity does not mean that it will always be better. The following two examples illustrate how polymerization can be either positive or negative:
 

• On the positive side, a well-made wine that has the right amount of micro-oxidative exposure will create beneficial, soft and agreeable tannin structures.  
   
• On the negative side, a wine that has an untreated H2S problem will also experience a transformation.  When the H2S molecules eventually polymerize together to become mercaptans, it‟s an even bigger problem than the original H2S.  

 
Both of these are examples of a wine gaining complexity, but they couldn‟t be further apart in terms of their desirability. In addition, due to polymerization can cause a wine that seemed sound just after fermentation to develop problems (such as H2S) during the aging/storage period - yet another reason to keep checking in with the wine as it ages. The important thing to take from each of these examples is that wine will continue to evolve/polymerize as it ages.  We have to constantly pay attention to the process in order to not get caught off-guard by any potentially negative developments.   Now that we have an idea of how constant polymerization in wine creates the need to monitor it, let‟s look at the other elements involved in developing the wine. We‟ll first look at temperature and later focus on SO2 management.

Temperature (control)

Temperature plays a large role in the speed at which complexing reactions take place; at higher temperature the process is accelerated, at lower ones they are slowed. There are pros and cons to both high and low aging/storage temperatures:
 
Warmer wine/cellar temperatures

Pros:  

• Warm temperatures of >65°F cause the polymerizing reactions to happen at a faster rate. This can be convenient; it saves time, making the wine ready for bottling/consumption earlier.  

Cons:  

• Higher temperatures can cause an imbalance in the ratio of compounds that are being extracted from the oak and integrated into the wine. This can lead to the wine becoming verloaded and out of balance. The following analogy can help illustrate this: If, while in the process of making gravy, we gradually add flour into the simmering broth a little bit at a time, everything becomes well integrated and we get a nice, smooth gravy. However, if we add the entire amount of flour as a single condensed dump, we can see that the broth has difficulty integrating the elevated amount of flour.  The broth becomes overloaded, and we end up with lumpy gravy. The same happens with wine and oak. In this case, the temperature of the wine/barrel determines the rate of extraction of compounds coming from the wood into the wine. If the temperature is too high then we get a larger percentage of compounds – most notably tannins - being introduced into the wine in a short period of time.  So, just like the gravy reacted to the flour, we run the risk of overloading the wine before it can gracefully integrate these extracted compounds.

• Elevated temperatures promote quicker oxidative reactions if the wine becomes exposed to oxygen. This often creates a rapid loss of free SO2 levels that leave your wine unprotected.  When this happens quickly, there is a shorter window in which you can catch the problem and address it. Even if you do catch the problem, while it is still treatable, the wine will have a more serious flaw than it would have if it had been stored at a cooler temperature.
   
• Finally, the rate of microbial spoilage becomes accelerated at higher temperatures. Again, this means that if there is a contamination problem, the impact of that infection will be more advanced by the time you realize it and take corrective action.

Cooler wine/cellar temperatures

Pros:

• Cooler temperatures of <50°F slow down and limit the activity of microorganisms. This is quite helpful if the wine becomes exposed to any spoilage organisms.  If the wine is cold enough, they will not be able to establish themselves enough to cause damage. 
  
  (*Note that cold temperatures will not necessarily kill these microbes; it just retards their rate of reproduction. If they are present and the SO2 is not correctly maintained, they can still come out of “hibernation” and spoil your wine if it were to warm up again.)

Cons:

• When wine is kept at cooler than normal cellaring temperatures (<55°F) the complexing reactions are slowed down and the amount of time the wine needs to become ready for bottling takes longer. This does not have an ill effect on the wine; it just ties up carboys, tanks and barrels that will not be available if you happen to need them before the wine being stored in them is finished.

 

• Cooler temps increase the amount of gas that can remain saturated in a solution. For winemakers, this means that you need to be careful when racking cold wine in order to avoid picking up too much oxygen on the transfer. Purging headspaces with inert gas will help to limit any oxidative uptake problems.

 
Ideal wine/cellaring temperature

The ideal cellar temperature is a compromise between the two extremes.  For red wines this equates to maintaining a range of 55-60°F. This allows the wine to be cool enough to limit microbial growth while effectively regulating the extraction of compounds from the oak and rate of polymerization.
 
 
See our Guide to SO2 Management for additional information on sulfite additions

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