How Inert Gas Is Used in Winemaking

Most people have heard about the variety of applications that use specialty gases. From welding and cutting, to research in laboratories, to the pharmaceutical industry, the widespread employment of compressed gases seem almost limitless. However, less commonly discussed is the employment of specialty gases in an industry that directly pertains to nearly all people everywhere- the food and beverage industry. For instance, whether you’re a wine aficionado or someone who prefers the occasional glass at dinner, you might not be aware that certain specialty gases actually play a very important role in the process of making wine.

If a wine is not constantly protected from both oxygen and microbial spoilage during the aging process, it will probably be spoiled. In order to protect the wine, it is necessary to maintain satisfactory sulfur dioxide levels and keep containers full. Additionally, the amount of protection is considerably increased by purging headspaces with inert gas in order to remove the oxygen. In regards to sulfur dioxide, its beneficial uses and details about its utilization in this process can be seen in most winemaking literature. Nonetheles, while these texts may briefly discuss purging with inert gas, they often do not effectively explain the actual techniques required 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 create a sufficient gas blanket to protect your wine. The purpose of this article is to explain the techniques needed to properly use inert gas to purge headspaces in order to successfully safeguard your wine. First, we will discuss the significance of safeguarding your wine from coming into contact with oxygen, and after 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 commonly known, the air we breathe is a mixture of gases, roughly 20% of which is oxygen. While a steady supply of oxygen is crucial for humans, it is certainly not beneficial when it comes to the successful 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, lengthy period of time, then the resulting changes generate undesireable flaws in the wine such as a diminishing of freshness, browning, sherry-like smells and taste, and acidity production. Wines exhibiting theseflaws are referred to as oxidized, because they result from exposure to oxygen. One of the main objectives in sufficient wine aging is learning the best methods to lower 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 eliminate headspace. Nevertheless, this approach may not always be feasible.

Unless you are storing your wine in a storage vessel that is guaranteed 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 occur to the liquid when the temperature changes. 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. 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 faces an increase in temperature, it will expand and the resulting pressure will end in 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 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 decline, on the other hand, the lids would be pulled inward as an effect of the liquid contracting. Thus, if there is a likelihood that your wine could experience temperature changes throughout 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 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 are actually heavier than air, a property that proves advantageous to winemakers. Purging headspaces with either carbon dioxide or argon, when properly executed, can eliminate oxygen by lifting it up and eliminating 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 ramifications during its storage/aging process. The key to properly protecting the wine in this way is to understand the specific techniques needed for the effective generation of this protective blanket.

There are 3 steps that are helpful to create a protective inert gas blanket. The first step is protecting purity by avoiding turbulence. When utilizing carbon dioxide or argon to create [[a successful|an effective|a sufficient[122] blanket, it is useful to know that the gases readily combine 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. Larger 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’ capability to preserve the wine is decreased as a result of its decreased purity. It is essential to make sure that the delivery method attempts 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 needed to accomplish 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 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 necessary to avoid creating turbulence and thus blending the gas with the air we are attempting to eliminate. While any size tubing can used 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 necessary to creating a successful blanket, the diameter of the output tubing should be expanded. A simple way to achieve 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 properly forming an inert gas blanket is to have the gas flow parallel to the surface of the wine, or laminar, instead of aiming 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. An effective and easy way 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 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 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 is inserted just a little below the rim of the vessel. If the lighter remains lit, there is still oxygen remaining in the vessel and you should keep adding the inert gas. Keep employing the lighter test until the flame eventually subsides, which will indicate that there is no more oxygen.

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