How Inert Gas Is Used in Winemaking

Many people have heard about the variety of applications that use specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the variety of uses 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 dinner, you may be unaware that certain specialty gases actually are a significant factor 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 spoil. In order to preserve the wine, it is necessary to maintain sufficient sulfur dioxide levels and keep containers full. Additionally, 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 use in this process can be read in the majority of winemaking literature. Yet, while these texts may touch on purging with inert gas, they usually do not efficiently explain the actual techniques required to perform the application. First, it should be understood that it requires more than just dispensing some argon into the headspace of your vessel in order to implement a sufficient gas blanket to safeguard your wine. The goal of this article is to describe the techniques required to properly use inert gas to purge headspaces in order to successfully preserve your wine. First, we will mention the priority of safeguarding your wine from coming into contact with 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 widely known, the air we breathe is a mix of gases, approximately 20% of which is oxygen. While a consistent supply of oxygen is crucial for humans, it is certainly not beneficial when it comes to the safe 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 unwanted flaws in the wine such as a reduction of freshness, browning, sherry-like smells and taste, and acidity production. Wines exhibiting theseunwanted characteristics are referred to as oxidized, because they result from exposure to oxygen. One of the key objectives in proper 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. Unfortunately, this method 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 should have a small headspace at the top in order to facilitate the contraction and expansion that occur to the liquid when the temperature changes. Because gas iseasier to compress than liquid, it does not significantly increase the pressure in the storage unit if there is some space left at the top. This is the reason 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 faces a rise 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 rises in temperature, this pressure could even be enough to push the tank lids out completely. If this were to occur, 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 an effect of the liquid contracting. Thus, if there is a possibility that your wine could face temperature variations throughout 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 simultaneously 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 advantageous to winemakers. Purging headspaces with either carbon dioxide or argon, when properly carried out, can rid the vessel of oxygen by lifting it up and eliminating it from the storage vessel, similar to how oil can float on the surface of water. The oxygen in the vessel has now been properly displaced by inert gas, and the wine can remain safe from negative reactions during its storage/aging process. The key to correctly safeguarding the wine in this way is to understand the specific techniques necessary for the proper formation of this protective blanket.

There are 3 steps recommended to generate a protective inert gas blanket. The first step is maintaining purity by avoiding turbulence. When utilizing carbon dioxide or argon to create [[a successful|an effective|a sufficient[122] blanket, it is useful to understand that the gases readily mix with each other when moved. When seeking to purge headspaces with inert gas, the gas’s flow rate as it exits the tubing acts as the determining factor in the purity of the final volume of gas. Greater flow rates lead to the creation of a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. In this scenario, the inert gas’ capacity to safeguard the wine is diminished due its decreased purity. It is vital to be sure that the delivery method tries to avoid turbulence as much as possible in order to have a pure layer of inert gas that is lacking oxygen. The ideal flow rate required to succeed in doing this is usually the lowest setting on your gas regulator. Most often, this means between 1-5 PSI, depending on the tubing size.

The second step to forming a protective inert gas blanket is to reach the highest volume of gas that can be delivered while still maintaining the low flow-rate necessary to avoid creating turbulence and thus combining the gas with the air we are attempting to get rid of. While any size tubing can used in the delivery of a sufficient inert gas blanket, the amount of time it calls for will increase as the delivery tubing diameter decreases. If you want to shorten the process of purging without compromising the gentle flow needed to generate a successful blanket, the diameter of the output tubing should be expanded. One way to easily do this is to fasten a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and last step to effectively creating 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 results in 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. A simple and correct method to do so is to attach a diverter at the end of the gas tubing.

To wrap up everything we have learned, the recommended method for purging a headspace with inert gas is as follows: First, make the adequate adjustments on the  gas regulator to determine 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 suggested. 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 inside the vessel and you should keep dispensing the inert gas. Keep utilizing the lighter test until the flame eventually subsides, which will reveal that there is no longer oxygen in the vessel.

Whether you’re in search of specialty gases to be utilized in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Rocky Mountain Air Solutions has a plethora of products to meet all of the Denver specialty gas needs. Rocky Mountain Air Solutions has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Denver to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at pevans@rockymountainair.com or at (303) 777-6671.