How Inert Gas Is Used in Winemaking

A lot of people are aware of the variety of applications that use specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the widespread employment of compressed gases seem almost limitless. However, less commonly discussed is the employment of specialty gases in an industry that directly involves nearly all people everywhere- the food and beverage industry. As an example, whether you’re a wine expert or someone who likes the occasional glass at dinner, you may not know that there are some specialty gases actually play a very important role in the process of making wine.

If a wine is not protected from both oxygen and microbial spoilage during the aging process, it will most likely go bad. In order to protect the wine, it is necessary to maintain adequate sulfur dioxide levels and keep containers full. Likewise, the level of protection is considerably increased by purging headspaces with inert gas in order to remove the oxygen. In regards to sulfur dioxide, its beneficial uses and details about its employment in this process can be found in most winemaking literature. Nonetheles, while these texts may touch on purging with inert gas, they frequently do not efficiently explain the actual techniques required to carry out the application. First, it should be understood that it requires more than merely dispensing some argon into the headspace of your vessel in order to create an effective gas blanket to protect your wine. The goal of this article is to describe the techniques required to effectively use inert gas to purge headspaces in order to successfully protect your wine. First, we will detail the importance of safeguarding your wine from being exposed to oxygen, and after we will explain the precise gas purging methods required to do so.

The space in a barrel or tank that is not filled by liquid is filled by gas. As is widely known, the air we breathe is a mixture of gases, approximately 20% of which is oxygen. While a consistent supply of oxygen is necessary for humans, it is certainly not beneficial when it comes to the proper storage of most wines. The reason for this is that a series of chemical changes occur to wine when exposed to oxygen. If wine is exposed to oxygen for an uncontrolled, long period of time, then the following changes generate undesireable flaws in the wine such as a diminishing of freshness, browning, sherry-like smells and taste, and acidity production. Wines possessing theseimperfections are referred to as oxidized, since they occur upon exposure to oxygen. One of the primary objectives in sufficient wine aging is learning the best techniques to lower the wine’s oxygen exposure in order to avoid oxidation. One easy method to do so is to fill the wine’s storage vessel as full as possible, in order to remove headspace. Nevertheless, this technique may not always be possible.

Unless you are storing your wine in a storage vessel that is made certain to resist temperature changes, carboys and tanks must have a small headspace at the top in order to facilitate the contraction and expansion that the liquid faces as a result of changes in temperature. Because gas iseasier to compress than liquid, it does not add a lot of pressure the storage unit if there is some space left at the top. It is because of this that you find a quarter-of-an-inch space below the cork in a new bottle of wine. If there is no headspace and the wine is exposed to a spike in temperature, it will expand and the subsequent pressure will end in the full force of the liquid being pushed against the lid. In some extreme spikes in temperature, this pressure could even be enough to push the tank lids out fully. If this were to happen, not only have you potentially caused a mess and lost wine, but your wine is now exposed to elements that could lead to its spoiling. In an extreme temperature decline, on the other hand, the lids would be pulled inward as a result of the liquid contracting. Thus, if there is a chance that your wine could be exposed to temperature fluctuations amid its storage, headspace should be left at the top of vessels.

While we now know we must have a headspace, we still are left with the problem of leaving room for contraction and expansion while still avoiding the negative effects of oxidative reactions. The answer, however, is found by replacing the headspace air that contains oxygen with an inert gas, such as argon, nitrogen, or carbon dioxide. These gases, unlike oxygen, do not negatively react with wine. In fact, carbon dioxide and argon actually weigh more than air, a property that proves valuable to winemakers. Purging headspaces with either carbon dioxide or argon, when properly carried out, can eliminate oxygen by lifting it up and removing it from the storage vessel, similar to how oil can float on the surface of water. The oxygen in the vessel has now been sufficiently displaced by inert gas, and the wine can remain safe from negative effects during its storage/aging process. The key to effectively preserving the wine in this way is to understand the specific techniques necessary for the proper formation of this protective blanket.

There are 3 steps that are helpful to generate a protective inert gas blanket. The first step is protecting purity by avoiding turbulence. When using carbon dioxide or argon to create [[a successful|an effective|a sufficient[122] blanket, it is essential to know that the gases readily mix with each other when moved. When attempting to purge headspaces with inert gas, the determining factor in the purity of the final volume of gas is the gas’s flow rate as it exits the tubing. Larger flow rates generate a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. If this happens, the inert gas’ ability to protect the wine is decreased as a result of its decreased purity. It is necessary to ensure that the delivery method tries to avoid turbulence as much as possible in order to have a pure layer of inert gas that contains little oxygen. The ideal flow rate required to succeed in doing this is most often the lowest setting on your gas regulator. Usually, this means between 1-5 PSI, depending on the tubing size.

The second step to generating a protective inert gas blanket is to reach the highest volume of gas that can be delivered while still maintaining the low flow-rate that is vital to avoid creating turbulence and therefore blending the gas with the air we are trying to remove. While any size tubing can used in the delivery of an effective inert gas blanket, the amount of time it needs will increase as the delivery tubing diameter decreases. If you want to speed up the process of purging without compromising the gentle flow necessary to creating a successful blanket, the diameter of the output tubing must be increased. One way to easily do this is to attach a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and last step to properly forming an inert gas blanket is to have the gas flow parallel to the surface of the wine, or laminar, instead of directing the flow of gas directly at the surface. This leads to the inert gas being less likely to combine with the surrounding air when being delivered because it will not bounce off the surface of the liquid. An effective and easy way to do so is to attach a diverter at the end of the gas tubing.

To wrap up everything we have learned, the suggested method for purging a headspace with inert gas is as follows: First, make the adequate adjustments on the  gas regulator to create a flow rate that is as high as possible while still maintaining a gentle, low-pressure flow. Then, lower the tubing into the storage vessel and arrange it so that the output is close to the surface of the wine, roughly 1-2 inches from the surface is best. Next, turn on the gas and initiate the purging. Finally ,to check the oxygen levels, use a lighter and lower the flame until it enters the vessel just barely below the rim. If the lighter remains lit, there is still oxygen remaining in the vessel and you should keep adding the inert gas. Keep using the lighter test until the flame eventually goes out, which will reveal that there is no longer oxygen in the vessel.

Whether you’re looking for specialty gases to be used in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Cee Kay Supply, Inc. has a plethora of products to meet all of the St. Louis specialty gas needs. Cee Kay Supply, Inc. has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in St. Louis to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at benv@ceekay.com or at 314.644.3500.