How Inert Gas Is Used in Winemaking

Several people are familiar with the large number 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 no matter their location- the food and beverage industry. For instance, whether you’re a wine aficionado 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 protect the wine, it is vital to maintain sufficient sulfur dioxide levels and keep containers full. Additionally, the extent of protection is notably increased by purging headspaces with inert gas in order to eliminate the oxygen. In regards to sulfur dioxide, its advantages and details about its use in this process can be found in the majority of winemaking literature. However, while these texts may touch on purging with inert gas, they usually do not effectively illustrate the actual techniques needed to perform the application. First, it needs to be understood that it requires more than merely dispensing some argon into the headspace of your vessel in order to implement an effective gas blanket to protect your wine. The goal of this article is to describe the techniques necessary 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 being exposed to oxygen, and later 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 generally known, the air we breathe is a blend of gases, roughly 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 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, extended period of time, then the following changes produce not wanted flaws in the wine such as a diminishing of freshness, browning, sherry-like smells and taste, and acidity production. Wines containing theseunwanted characteristics are referred to as oxidized, because they occur as a result of exposure to oxygen. One of the main objectives in correct wine aging is learning the best methods to reduce the wine’s oxygen exposure in order to avert oxidation. One easy method to do so is to fill the wine’s storage vessel as full as possible, in order to get rid of headspace. Unfortunately, this method may not always be attainable.

Unless you are storing your wine in a storage vessel that is made certain to keep the wine at a stable temperature, 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 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 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 is exposed to a rise in temperature, it will expand and the subsequent pressure will lead to the full force of the liquid being pushed against the lid. In some extreme spikes in temperature, this pressure could even be enough to push the tank lids out completely. If this were to happen, not only have you potentially made a mess and lost wine, but your wine is now exposed to elements that could cause spoilage. In an extreme temperature drop, 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 be exposed to temperature fluctuations amid 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 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 valuable to winemakers. Purging headspaces with either carbon dioxide or argon, when properly performed, can rid the vessel of oxygen by lifting it up and removing 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 effects during its storage/aging process. The key to properly safeguarding the wine in this way is to be aware of the specific techniques required for the proper formation of this protective blanket.

There are 3 steps suggested to create a protective inert gas blanket. The first step is preserving purity by avoiding turbulence. When employing carbon dioxide or argon to form [[a successful|an effective|a sufficient[122] blanket, it is significant to understand that the gases readily mix 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. Higher 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’ capacity to safeguard the wine is reduced because of its decreased purity. It is essential to make sure that the delivery method makes effort 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 necessary to do 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 that is essential to avoid creating turbulence and therefore combining the gas with the air we are trying to remove. While any size tubing can applied 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 shorten 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. One way to easily do this is to attach a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and concluding 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 directing 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. A simple and correct method 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  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, roughly 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 remaining in the vessel and you should keep dispensing the inert gas. Keep using the lighter test until the flame eventually extinguishes, which will illustrate that the oxygen is gone.

Whether you’re seeking specialty gases to be applied in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Fresno Oxygen & Welding Supplies/Barnes Welding Supply has a plethora of products to meet all of the Fresno specialty gas needs. Fresno Oxygen & Welding Supplies/Barnes Welding Supply has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Fresno to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at info@barnesspecialtygases.com or at 559-341-4456.