How Inert Gas Is Used in Winemaking

Several people are familiar with the large number 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 unending. However, less commonly discussed is the employment of specialty gases in an industry that directly pertains to nearly all people worldwide- the food and beverage industry. For instance, whether you’re a wine aficionado or someone who enjoys the occasional glass at certain events, you may not know that some specialty gases actually have a significant impact 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 safeguard the wine, it is crucial to maintain satisfactory sulfur dioxide levels and keep containers full. Additionally, the amount 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 employment in this process can be read in most winemaking literature. Yet, while these texts may touch on purging with inert gas, they usually do not sufficiently explain the actual techniques required to perform the application. First, it needs to 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 required to adequately use inert gas to purge headspaces in order to successfully preserve your wine. First, we will mention the importance of safeguarding your wine from exposure to oxygen, and later 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 generally known, the air we breathe is a mixture of gases, approximately 20% of which is oxygen. While a steady supply of oxygen is important for humans, it is certainly not beneficial when it comes to the proper 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, long period of time, then the resulting changes create unwanted flaws in the wine such as a decrease of freshness, browning, sherry-like smells and taste, and acidity production. Wines possessing theseflaws are referred to as oxidized, because they occur as a result of exposure to oxygen. One of the primary objectives in sufficient 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 it can be, in order to get rid of headspace. However, this approach may not always be possible.

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 must 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 iscompressed more easily than liquid, it does not significantly increase the pressure in the storage unit if there is some space left at the top. This is the 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 is exposed to an increase 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 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 made 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 likelihood that your wine could be exposed to temperature changes 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 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 do not create negative reactions with the 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 performed, 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 effectively displaced by inert gas, and the wine can remain safe from negative effects during its storage/aging process. The primary factor to properly preserving the wine in this way is to be aware of the specific techniques needed for the proper formation of this protective blanket.

There are 3 steps that are helpful to generate a protective inert gas blanket. The first step is maintaining purity by avoiding turbulence. When utilizing carbon dioxide or argon to form [[a successful|an effective|a sufficient[122] blanket, it is essential to know that the gases readily mix with each other when moved. When attempting to purge headspaces with inert gas, the purity of the final volume of the gas is determined by the gas’s flow rate as it exits the tubing. Greater flow rates lead to the creation of a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. If this happens, the inert gas’ capability to safeguard the wine is diminished due 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 has a minimum amount of oxygen. The ideal flow rate needed to accomplish this is most often the lowest setting on your gas regulator. Typically, this means between 1-5 PSI, depending on the tubing size.

The second step to creating a protective inert gas blanket is to find the highest volume of gas that can be delivered while still maintaining the low flow-rate required to avoid creating turbulence and therefore mixing the gas with the air we are attempting to eliminate. While any size tubing can employed in the delivery of an adequate 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 necessary to creating 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 last 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 pointing 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 correct adjustments on the  gas regulator to determine 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 preferred. Next, turn on the gas and initiate the purging. Finally ,to check the oxygen levels, use a lighter and lower the flame until it is inserted just a little below the rim of the vessel. If the lighter remains lit, there is still oxygen inside the vessel and you should keep dispensing the inert gas. Keep employing the lighter test until the flame eventually subsides, which will reveal that there is no longer oxygen in the vessel.

Whether you’re needing specialty gases to be utilized in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Toll Company has a plethora of products to meet all of the Minneapolis specialty gas needs. Toll Company has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Minneapolis to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at thea@tollgas.com or at 612-581-9889.