How Inert Gas Is Used in Winemaking

Many people have heard about the variety of applications that employ specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the variety of uses of compressed gases seem almost limitless. However, less commonly discussed is the employment 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 expert or someone who prefers the occasional glass at dinner, you might not be aware that some specialty gases actually play a very important role 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 safeguard the wine, it is crucial to maintain sufficient sulfur dioxide levels and keep containers full. Likewise, the extent 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 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 often do not sufficiently describe the actual techniques necessary 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 effectively use inert gas to purge headspaces in order to successfully safeguard your wine. First, we will discuss the priority of safeguarding your wine from exposure to oxygen, and later 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 generally known, the air we breathe is a mixture of gases, approximately 20% of which is oxygen. While a steady supply of oxygen is necessary for humans, it is certainly not beneficial when it comes to the safe 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, long period of time, then the resulting changes generate not wanted flaws in the wine such as a decrease of freshness, browning, sherry-like smells and taste, and acidity production. Wines containing theseunwanted characteristics are referred to as oxidized, because they result from exposure to oxygen. One of the key objectives in correct wine aging is learning the best ways to reduce 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 get rid of headspace. Unfortunately, this technique may not always be attainable.

Unless you are storing your wine in a storage vessel that is assured to resist temperature changes, carboys and tanks need to have a small headspace at the top in order to facilitate the 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 significantly increase the pressure in 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 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 entirely. 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 lead to its spoiling. In an extreme temperature drop, on the other hand, the lids would be pulled inward as a result of the liquid contracting. Thus, if there is a chance that your wine could face temperature fluctuations during its storage, headspace should be left at the top of vessels.

While we now know we must leave a headspace, there is still the problem of leaving room for contraction and expansion while at the same time 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 have a greater weight than air, a property that proves beneficial to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, can get rid 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 reactions during its storage/aging process. The key to properly protecting the wine in this way is to understand the specific techniques required for the effective generation 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 using carbon dioxide or argon to create [[a successful|an effective|a sufficient[122] blanket, it is important to be aware that the gases readily blend 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. Greater flow rates lead to a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. If this happens, the inert gas’ ability to protect the wine is decreased as a result of its decreased purity. It is necessary to ensure that the delivery method tries 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 required to succeed in doing this is most often the lowest setting on your gas regulator. Usually, this means between 1-5 PSI, depending on the tubing size.

The second step to generating 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 vital to avoid creating turbulence and thus mixing the gas with the air we are attempting to get rid of. 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 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. 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 last 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 pointing the flow of gas directly at the surface. This will have the effect of 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 correct adjustments on the  gas regulator to find 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, roughly 1-2 inches from the surface is suggested. Next, turn on the gas and initiate the purging. Finally ,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 in the vessel and you should keep dispensing the inert gas. Keep using 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 employed in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Noble Gas Solutions has a plethora of products to meet all of the Albany specialty gas needs. Noble Gas Solutions has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Albany to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at sales@noblegassolutions.com or at (518) 465-5229.