Many 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 variety of uses of compressed gases
seem almost unending. However, less commonly
discussed is the use of specialty gases in an
industry that directly affects nearly all people everywhere- the food and beverage industry. For example, whether you’re a wine connoisseur
or someone who prefers the occasional glass at dinner, you may be unaware that certain specialty gases actually are a significant factor 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 spoil. In order to preserve
the wine, it is necessary to maintain
satisfactory sulfur dioxide levels and keep
containers full. Additionally, the level
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 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 usually
do not efficiently explain the actual
techniques required to perform
the application. First, it should be understood that it
requires more than just dispensing some argon into the
headspace of your vessel in order to implement a sufficient gas blanket to safeguard
your wine. The goal of this article is to describe
the techniques required to properly
use inert gas to purge headspaces in order to successfully preserve
your wine. First, we will mention the priority
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 widely known, the air we
breathe is a mix of gases, approximately
20% of which is oxygen. While a constant supply of
oxygen is crucial 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, long
period of time, then the following changes generate
unwanted flaws in the wine such as a reduction
of freshness, browning, sherry-like smells and taste, and acidity production. Wines
exhibiting theseunwanted
characteristics are referred to as oxidized, because they result from exposure to oxygen. One
of the key objectives in proper
wine aging is learning the best techniques 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. Unfortunately, this method
may not always be possible.
Unless you are storing your wine in a storage vessel that is
made certain to resist
temperature changes, carboys and
tanks should 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
iseasier to compress 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 faces a rise in temperature, it will expand
and the subsequent pressure will result
in the full force of the liquid being pushed against the lid. In
some extreme rises in temperature, this pressure could
even be enough to push the tank lids out entirely. If
this were to occur, 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
decline, 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 variations
throughout its storage,
headspace should be left at the top of vessels.
While we now know we must leave a headspace,
we still are left with the problem of leaving room for contraction and expansion while simultaneously 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 have negative impacts on the
wine. In fact, carbon
dioxide and argon actually weigh more than air, a property that proves advantageous
to winemakers. Purging headspaces with either carbon dioxide or argon, when
properly carried out, can rid
the vessel of 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 properly
displaced by inert gas, and the wine can remain safe from negative reactions
during its storage/aging process. The key to correctly protecting
the wine in this way is to understand the
specific techniques necessary for the proper formation of this protective
blanket.
There are 3 steps recommended to create a protective inert gas blanket. The
first step is maintaining purity by avoiding
turbulence. When using carbon dioxide or argon to create
[[a successful|an effective|a sufficient[122] blanket, it is useful
to understand 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. 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 safeguard 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 is lacking oxygen. The ideal flow rate required to succeed in doing 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 reach the highest volume
of gas that can be delivered while still maintaining the low flow-rate necessary to avoid creating turbulence and thus
combining the gas with the air we are attempting to get rid of. While any size tubing
can used in the delivery of a
sufficient inert gas blanket, the amount of time it calls
for 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. One way to easily do this is to fasten 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 results in 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 recommended method for purging a headspace with inert gas is as follows:
First, make the adequate 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, place the tubing into the storage
vessel and arrange it so that the output is close to the surface of the wine, approximately
1-2 inches from the surface is suggested.
Next, turn on the gas and initiate the purging. Then ,to
check the oxygen levels, use a lighter and lower the flame until it enters the vessel just barely below the rim. If the lighter remains
lit, there is still oxygen inside the vessel and you
should keep dispensing the inert gas. Keep utilizing
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 utilized
in winemaking, other food and beverage applications, or any other industry that
utilizes specialty gases, Rocky Mountain Air Solutions has a plethora of products to meet
all of the Denver specialty gas needs. Rocky Mountain Air Solutions has a large
selection of specialty gases and specialty gas equipment, along with the
resources and experts on hand in Denver to answer your questions
and assist your needs. For more information, browse our online catalog or contact us via email at pevans@rockymountainair.com or at (303) 777-6671.