How Inert Gas Is Used in Winemaking

Several people are familiar with the large number of applications that call for specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the uses and applications of compressed gases seem almost unending. However, less commonly discussed is the use of specialty gases in an industry that directly affects nearly all people everywhere- the food and beverage industry. For example, whether you’re a wine connoisseur or someone who prefers the occasional glass at certain events, you might not be aware 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 probably be spoiled. In order to safeguard the wine, it is important to maintain adequate sulfur dioxide levels and keep containers full. Likewise, the amount 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 use in this process can be read in most winemaking literature. Nonetheles, while these texts may briefly discuss purging with inert gas, they often do not sufficiently explain the actual techniques required to perform 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 a sufficient gas blanket to preserve your wine. The goal of this article is to discuss the techniques needed to effectively use inert gas to purge headspaces in order to successfully safeguard your wine. First, we will discuss the priority of safeguarding your wine from being exposed to oxygen, and afterwards we will explain the precise gas purging methods necessary to do so.

The space in a barrel or tank that is not filled by liquid is filled by gas. As is generally 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 successful storage of most wines. This is because a series of chemical changes occur to wine when exposed to oxygen. If wine is exposed to oxygen for an uncontrolled, lengthy period of time, then the resulting changes create not wanted flaws in the wine such as a decrease of freshness, browning, sherry-like smells and taste, and acidity production. Wines possessing theseflaws are referred to as oxidized, because they occur as a result of exposure to oxygen. One of the key objectives in correct wine aging is learning the best techniques to decrease 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 eliminate headspace. However, this approach may not always be possible.

Unless you are storing your wine in a storage vessel that is assured to keep the wine at a stable temperature, carboys and tanks need to 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 is more easily compressed than liquid, it does not significantly increase the pressure in 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 experiences an increase in temperature, it will expand and the subsequent pressure will result in the full force of the liquid being pushed against the lid. In some extreme increases in temperature, this pressure could even be enough to push the tank lids out entirely. If this were to occur, not only have you potentially made a mess and lost wine, but your wine is now exposed to elements that could lead to its spoiling. In an extreme temperature decrease, on the other hand, the lids would be pulled inward as a consequence of the liquid contracting. Thus, if there is a likelihood that your wine could experience temperature variations throughout its storage, headspace should be left at the top of vessels.

While we now know we must keep a headspace, we still are left with the problem of leaving room for contraction and expansion while simultaneously avoiding the negative effects of oxidative reactions. The resolution, 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 advantageous to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, can get rid of oxygen by lifting it up and extracting 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 ramifications during its storage/aging process. The primary factor to properly preserving the wine in this way is to understand the specific techniques required for the successful creation 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 form [[a successful|an effective|a sufficient[122] blanket, it is useful to understand that the gases readily combine with each other when moved. When trying 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. Greater flow rates lead to a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. If this occurs, the inert gas’ capability to preserve the wine is decreased as a result of its decreased purity. It is necessary to ensure that the delivery method makes effort 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 usually the lowest setting on your gas regulator. Usually, this means between 1-5 PSI, depending on the tubing size.

The second step to creating a protective inert gas blanket is to find the highest volume of gas that can be delivered while still maintaining the low flow-rate necessary to avoid creating turbulence and therefore combining the gas with the air we are attempting to eliminate. While any size tubing can employed in the delivery of a sufficient 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 needed to generate a successful blanket, the diameter of the output tubing should be expanded. A simple way to achieve this is to connect a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and final step to correctly generating an inert gas blanket is to have the gas flow parallel to the surface of the wine, or laminar, instead of pointing the flow of gas directly at the surface. This will have the effect of the inert gas being less likely to blend 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 combine all the we have discussed, the suggested method for purging a headspace with inert gas is as follows: First, make the adequate adjustments on the  gas regulator to find a flow rate that is as high as possible while still maintaining a gentle, low-pressure flow. Then, place the tubing into the storage vessel and arrange it so that the output is close to the surface of the wine, approximately 1-2 inches from the surface is best. Next, turn on the gas and initiate the purging. Then ,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 employing the lighter test until the flame eventually subsides, which will illustrate that the oxygen is gone.

Whether you’re in search of specialty gases to be employed in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Sidney Lee Medical & Scientific Gases has a plethora of products to meet all of the Atlanta, GA specialty gas needs. Sidney Lee Medical & Scientific Gases has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Atlanta, GA to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at Grace.hoffman@sidneylee.com or at 770-946-4287 .