How Inert Gas is Used in Winemaking

Most people are familiar with the variety of applications that utilize 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 commonly discussed is the use of specialty gases in an industry that directly affects nearly all people worldwide- the food and beverage industry. For example, whether you’re a wine connoisseur or someone who enjoys the occasional glass at dinner time, you might not be aware that certain specialty gases actually play a very important role in the process of making wine.

If a wine does not remain constantly protected from both oxygen and microbial spoilage during the aging process, it will most likely spoil. In order to protect the wine, it is important to maintain sufficient sulfur dioxide levels and keep containers full. Likewise, the amount of protection is significantly increased by purging headspaces with inert gas in order to remove the oxygen. In regards to sulfur dioxide, its benefits and details about its utilization can be found in the majority of winemaking literature. However, while these texts may touch on purging with inert gas, they often do not effectively describe the actual techniques necessary to do carry out 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 an effective gas blanket to protect your wine. The purpose of this article is to explain the techniques required to effectively use inert gas to purge headspaces in order to successfully protect your wine. First, we will discuss the importance of safeguarding your wine from exposure to oxygen, and afterwards 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 commonly known, the air we breathe is a mix of gases, approximately 20% of which is oxygen. While a constant supply of oxygen is necessary for humans, it is certainly not beneficial when it comes to the successful 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, extended period of time, then the susbsequent changes produce unwanted flaws in the wine such as, decrease of freshness, browning, sherry-like smells and taste, and acidity production. Wines possessing these flaws are referred to as oxidized, since they occur upon exposure to oxygen. One of the main objectives in proper wine aging is learning the best ways to reduce 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 it can be, in order to eliminate headspace. However, this method may not always be possible.

Unless you are storing your wine in a storage vessel that is guaranteed to maintain temperature stability, carboys and tanks should have a small headspace at the top in order to facilitate 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 add significant pressure to the storage unit if there is some space left at the top. It is for this reason that you find a quarter-of-an-inch space below the cork in a new bottle of wine. If there is no headspace, if the wine faces a rise in temperature, it will expand and the resulting pressure will lead to 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. In an extreme temperature drop, on the other hand, the lids would be pulled inward as a result of the liquid contracting. If this were to happen, not only have you potentially created a mess and lost wine, but your wine is now exposed to elements that could cause spoilage. Thus, if there is a possibility that your wine could face temperature fluctuations throughout its storage, headspace should be left at the top of vessels.

While we now know we must leave 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 solution, 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 advantageous to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, can eliminate oxygen by lifting it up and removing it from the storage vessel, similar to how oil can float on water’s surface. The oxygen in the vessel has now been effectively displaced by inert gas, and the wine can remain safe from negative effects during its storage/aging process. The key to effectively protecting the wine in this way is to understand the specific techniques necessary to 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 create a successful blanket, it is important to understand that the gases readily mix with each other when moved. When attempting 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. Higher flow rates lead to the creation of a churning effect that causes the oxygen-containing ambient air to mix in with the inert gas. If this occurs, the inert gas’ ability to protect the wine is diminished due its decreased purity. It is necessary to ensure that the delivery method attempts 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 needed to accomplish this is generally the lowest setting on you 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 reach the highest volume of gas that can be delivered while still maintaining the low flow-rate necessary to avoid creating turbulence and thus mixing the gas with the air we are attempting to eliminate. While any size tubing can utilized in the delivery of an effective inert gas blanket, the amount of time it requires will increase as the delivery tubing diameter decreases. If you want to hasten the process of purging without compromising the gentle flow necessary to creating a successful blanket, the diameter of the output tubing should be expanded. One way to easily do this is to attach a small length of a larger diameter tube onto the existing gas line on your 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 aiming the flow of gas directly at the surface. This leads to 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. An effective and easy way to do so is to attach a diverter at the end of the gas tubing.

To put it all together, the recommended method for purging a headspace with inert gas is as follows: First, make the proper adjustments on the 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, approximately 1-2 inches from the surface is preferred. 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 dispensing the inert gas. Keep using the lighter test until the flame eventually goes out, which will indicate that there is no more oxygen.

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, PurityPlus has a plethora of specialty gas products to meet your need. We have a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand to answer your questions and assist your needs. For more information, browse our online catalog or contact us via our website or at 877-81P-PLUS (877-817-7587).