How Inert Gas Is Used in Winemaking

Most people have heard about 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 limitless. However, less frequently discussed is the use 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 connoisseur or someone who likes the occasional glass at certain events, you may be unaware that certain specialty gases actually have a significant impact 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 spoil. In order to preserve the wine, it is vital to maintain adequate sulfur dioxide levels and keep containers full. Additionally, the level of protection is considerably increased by purging headspaces with inert gas in order to get rid of the oxygen. In regards to sulfur dioxide, its beneficial uses and details about its utilization in this process can be seen in the majority of winemaking literature. However, while these texts may briefly discuss purging with inert gas, they frequently do not effectively explain the actual techniques required to perform the application. First, it must be understood that it requires more than simply dispensing some argon into the headspace of your vessel in order to create a sufficient gas blanket to safeguard your wine. The goal of this article is to describe the techniques needed to properly use inert gas to purge headspaces in order to successfully protect your wine. First, we will discuss the significance of safeguarding your wine from being exposed to oxygen, and afterwards we will explain the precise gas purging methods needed 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, about 20% of which is oxygen. While a consistent supply of oxygen is important for humans, it is certainly not beneficial when it comes to the safe 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, extended period of time, then the subsequent changes generate undesireable flaws in the wine such as a reduction of freshness, browning, sherry-like smells and taste, and acidity production. Wines containing theseunwanted characteristics 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 ways to lower the wine’s oxygen exposure in order to prevent oxidation. One easy method to do so is to fill the wine’s storage vessel as full as it can be, in order to eliminate headspace. Nevertheless, this approach may not always be feasible.

Unless you are storing your wine in a storage vessel that is assured to resist temperature changes, carboys and tanks should have a small headspace at the top in order to facilitate the contraction and expansion that that the liquid experiences as a result of temperature fluctuations. Because gas iscompressed more easily than liquid, it does not add significant pressure to 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 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 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 created a mess and lost wine, but your wine is now exposed to elements that could cause it to spoil. 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 chance that your wine could face temperature changes throughout its storage, headspace should be left at the top of vessels.

While we now know we must have a headspace, there is still 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 are actually heavier than air, a property that proves beneficial to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, can rid the vessel 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 reactions during its storage/aging process. The essential factor to effectively protecting the wine in this way is to be aware of the specific techniques required for the successful creation of this protective blanket.

There are 3 steps recommended to create a protective inert gas blanket. The first step is maintaining purity by avoiding turbulence. When using carbon dioxide or argon to form [[a successful|an effective|a sufficient[122] blanket, it is important to know that the gases readily blend 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. Larger flow rates generate a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. If this occurs, the inert gas’ capacity to preserve the wine is reduced because of its decreased purity. It is vital to be sure that the delivery method attempts 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 needed to accomplish this is usually the lowest setting on your gas regulator. Typically, this means between 1-5 PSI, depending on the tubing size.

The second step to forming a protective inert gas blanket is to attain 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 eliminate. While any size tubing can applied in the delivery of an adequate inert gas blanket, the amount of time it requires will increase as the delivery tubing diameter decreases. If you want to speed up the process of purging without compromising the gentle flow required to form a successful blanket, the diameter of the output tubing should be made larger. One easy way to accomplish this is to fasten a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and final 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 directing the flow of gas directly at the surface. This will have the effect of the inert gas being less likely to mix with the surrounding air when being delivered because it will not bounce off the surface of the liquid. A feasible method to do so is to attach a diverter at the end of the gas tubing.

To put it all together, the suggested method for purging a headspace with inert gas is as follows: First, make the adequate adjustments on the  gas regulator to generate a flow rate that is as high as possible while still maintaining a gentle, low-pressure flow. Then, insert the tubing into the storage vessel and arrange it so that the output is close to the surface of the wine, around 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 reaches just below the rim of the vessel. If the lighter remains lit, there is still oxygen remaining in the vessel and you should keep inserting the inert gas. Keep using the lighter test until the flame eventually subsides, which will indicate that there is no more oxygen.

Whether you’re in search of specialty gases to be applied in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Delille Oxygen Company has a plethora of products to meet all of the Columbus specialty gas needs. Delille Oxygen Company has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Columbus to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at scotta@delille.com or at (614) 444-1177.