How Inert Gas Is Used in Winemaking

A lot of people have heard about the multitude of applications that employ specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the uses and applications of compressed gases seem almost immeasurable. However, less often discussed is the utilization of specialty gases in an industry that directly involves 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 be unaware that there are some specialty gases actually have a significant impact 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 be spoiled. In order to protect the wine, it is necessary to maintain adequate sulfur dioxide levels and keep containers full. Also, the amount of protection is significantly 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 seen in the majority of winemaking literature. However, while these texts may touch on purging with inert gas, they often do not efficiently illustrate the actual techniques needed to carry out 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 generate a sufficient gas blanket to safeguard your wine. The function of this article is to discuss the techniques required to properly use inert gas to purge headspaces in order to successfully preserve your wine. First, we will discuss the importance of safeguarding your wine from coming into contact with oxygen, and afterwards 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 commonly known, the air we breathe is a blend of gases, about 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 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, lengthy period of time, then the following changes generate unwanted flaws in the wine such as a decrease 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 key objectives in proper wine aging is learning the best ways to decrease 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 it can be, in order to remove headspace. Unfortunately, this method may not always be feasible.

Unless you are storing your wine in a storage vessel that is made certain to maintain temperature stability, carboys and tanks need to 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 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 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 spikes in temperature, this pressure could even be enough to push the tank lids out fully. If this were to happen, not only have you potentially caused 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 an effect of the liquid contracting. Thus, if there is a chance that your wine could face temperature changes during its storage, headspace should be left at the top of vessels.

While we now know we must have 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 resolution, 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 advantageous to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, 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 reactions during its storage/aging process. The essential factor to effectively protecting the wine in this way is to be aware of the specific techniques required for the successful creation of this protective blanket.

There are 3 steps suggested 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 seeking 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. Higher 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 occurs, 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 contains little oxygen. The ideal flow rate necessary to do 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 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 hence blending the gas with the air we are attempting to get rid of. 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 hasten the process of purging without compromising the gentle flow necessary to creating a successful blanket, the diameter of the output tubing should be expanded. A simple way to achieve this is to fasten 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 pointing the flow of gas directly at the surface. This will have the effect of the inert gas being less likely to mix with the surrounding air when being delivered because it will not bounce off the surface of the liquid. A feasible method to do so is to attach a diverter at the end of the gas tubing.

To wrap up everything we have learned, the recommended method for purging a headspace with inert gas is as follows: First, make the adequate 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 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 adding the inert gas. Keep using the lighter test until the flame eventually subsides, which will indicate that there is no more oxygen.

Whether you’re seeking specialty gases to be used in winemaking, other food and beverage applications, or any other industry that utilizes specialty gases, Arc3 Gases has a plethora of products to meet all of the Richmond, Virginia specialty gas needs. Arc3 Gases has a large selection of specialty gases and specialty gas equipment, along with the resources and experts on hand in Richmond, Virginia to answer your questions and assist your needs. For more information, browse our online catalog or contact us via email at nickk@arc3gases.com or at (804) 644-4521.