How Inert Gas Is Used in Winemaking

A lot of people are aware of 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 limitless. However, less often discussed is the use of specialty gases in an industry that directly affects nearly all people worldwide- the food and beverage industry. For instance, whether you’re a wine expert or someone who prefers the occasional glass at dinner, you might not be aware that there are 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 be spoiled. In order to preserve the wine, it is vital to maintain adequate sulfur dioxide levels and keep containers full. Likewise, the level of protection is significantly increased by purging headspaces with inert gas in order to remove the oxygen. In regards to sulfur dioxide, its advantages and details about its utilization in this process can be seen in the majority of winemaking literature. Yet, while these texts may touch on purging with inert gas, they often do not effectively describe the actual techniques necessary to carry out 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 create a sufficient gas blanket to protect your wine. The function of this article is to describe the techniques necessary to effectively use inert gas to purge headspaces in order to successfully safeguard your wine. First, we will discuss the importance of safeguarding your wine from being exposed 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 widely known, the air we breathe is a mix of gases, approximately 20% of which is oxygen. While a consistent supply of oxygen is necessary for humans, it is certainly not beneficial when it comes to the safe 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 following changes produce unwanted flaws in the wine such as a diminishing of freshness, browning, sherry-like smells and taste, and acidity production. Wines possessing theseunwanted characteristics are referred to as oxidized, because they occur as a result of 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 avoid oxidation. One easy method to do so is to fill the wine’s storage vessel as full as possible, in order to remove headspace. However, this technique may not always be attainable.

Unless you are storing your wine in a storage vessel that is made certain to resist temperature changes, carboys and tanks must have a small headspace at the top in order to facilitate the contraction and expansion that that the liquid experiences as a result of temperature fluctuations. 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 following pressure will end 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 fully. If this were to occur, 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 drop, on the other hand, the lids would be pulled inward as an effect of the liquid contracting. Thus, if there is a possibility that your wine could face temperature changes amid its storage, headspace should be left at the top of vessels.

While we now know we must have a headspace, there is still the problem of leaving room for contraction and expansion while simultaneously 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 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 sufficiently displaced by inert gas, and the wine can remain safe from negative ramifications during its storage/aging process. The essential factor to effectively safeguarding the wine in this way is to be up to speed on the specific techniques needed for the effective generation of this protective blanket.

There are 3 steps that are helpful to form a protective inert gas blanket. The first step is protecting purity by avoiding turbulence. When employing carbon dioxide or argon to generate [[a successful|an effective|a sufficient[122] blanket, it is essential to understand that the gases readily combine with each other when moved. When trying 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 lead to the creation of a churning effect that causes the oxygen-containing surrounding air to mix in with the inert gas. In this scenario, the inert gas’ capacity to preserve the wine is decreased as a result of its decreased purity. It is vital to be sure 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 usually the lowest setting on your gas regulator. Most often, this means between 1-5 PSI, depending on the tubing size.

The second step to forming a protective inert gas blanket is to find the highest volume of gas that can be delivered while still maintaining the low flow-rate that is essential to avoid creating turbulence and thus combining 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 connect a small length of a larger diameter tube onto the existing gas line on your gas regulator.

The third and last 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 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 put it all together, the suggested method for purging a headspace with inert gas is as follows: First, make the correct 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, lower 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 best. 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 inside 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 seeking specialty gases to be utilized in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Cryo-Source has a plethora of products to meet all of the Portland specialty gas needs. Cryo-Source has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Portland to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at paulb@industrialsource.com or at 503-235-0168.