How Inert Gas Is Used in Winemaking

A lot of people are familiar with 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 immeasurable. However, less frequently discussed is the use of specialty gases in an industry that directly affects nearly all people worldwide- the food and beverage industry. As an example, whether you’re a wine expert or someone who likes the occasional glass at dinner, you might not be aware that certain specialty gases actually are a significant factor in the process of making wine.

If a wine is not constantly protected from both oxygen and microbial spoilage during the aging process, it will probably be spoiled. In order to protect the wine, it is necessary to maintain sufficient sulfur dioxide levels and keep containers full. Also, the level of protection is considerably increased by purging headspaces with inert gas in order to eliminate the oxygen. In regards to sulfur dioxide, its beneficial uses and details about its utilization in this process can be read in most winemaking literature. Yet, while these texts may touch on purging with inert gas, they frequently do not sufficiently illustrate the actual techniques needed to execute the application. First, it should be understood that it requires more than simply dispensing some argon into the headspace of your vessel in order to implement a sufficient gas blanket to protect your wine. The goal of this article is to explain the techniques needed to effectively use inert gas to purge headspaces in order to successfully preserve your wine. First, we will detail the priority of safeguarding your wine from coming into contact with 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, roughly 20% of which is oxygen. While a constant supply of oxygen is crucial for humans, it is certainly not beneficial when it comes to the proper storage of most wines. The explanation 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, lengthy period of time, then the subsequent changes create undesireable flaws in the wine such as a diminishing of freshness, browning, sherry-like smells and taste, and acidity production. Wines containing theseimperfections are referred to as oxidized, since they occur upon exposure to oxygen. One of the main 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 possible, in order to eliminate headspace. Nevertheless, this technique may not always be feasible.

Unless you are storing your wine in a storage vessel that is guaranteed to keep the wine at a stable temperature, carboys and tanks must 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 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 and the wine experiences a spike in temperature, it will expand and the following 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 completely. If this were to take place, not only have you potentially created 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 consequence of the liquid contracting. Thus, if there is a chance that your wine could experience temperature changes during its storage, headspace should be left at the top of vessels.

While we now know we must keep a headspace, the problem still remains of leaving room for contraction and expansion while at the same time 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 do not create negative reactions with the wine. In fact, carbon dioxide and argon actually have a greater weight 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 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 effectively displaced by inert gas, and the wine can remain safe from negative ramifications during its storage/aging process. The key to correctly protecting the wine in this way is to be aware of the specific techniques necessary for the effective generation of this protective blanket.

There are 3 steps recommended to form a protective inert gas blanket. The first step is maintaining purity by avoiding turbulence. When using carbon dioxide or argon to create [[a successful|an effective|a sufficient[122] blanket, it is useful to understand that the gases readily combine 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. Greater 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’ 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 has a minimum amount of oxygen. The ideal flow rate required to succeed in doing this is generally 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 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 thus mixing 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 needed to generate a successful blanket, the diameter of the output tubing should be made larger. 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 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. 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 best way 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, place 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 recommended. Next, turn on the gas and initiate the purging. Lastly ,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 adding the inert gas. Keep utilizing the lighter test until the flame eventually extinguishes, which will illustrate that the oxygen is gone.

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, Wright Brothers has a plethora of products to meet all of the Cincinnati specialty gas needs. Wright Brothers has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Cincinnati to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at mike@expectthebest.com or at 800-637-2222.