A lot of people are
aware of 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 often
discussed is the employment of specialty gases in an
industry that directly involves nearly all people everywhere- the food and beverage industry. As an example, whether you’re a wine expert
or someone who likes the occasional glass at dinner, you may not know 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 most likely spoil. In order to protect
the wine, it is necessary to maintain
adequate sulfur dioxide levels and keep
containers full. Likewise, the level
of protection is considerably increased by purging
headspaces with inert gas in order to eliminate the
oxygen. In regards to sulfur dioxide, its beneficial
uses and details about its employment in
this process can be found in most winemaking literature. Nonetheles, while these texts
may touch on purging with inert gas, they frequently
do not sufficiently explain the actual
techniques required 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 an
effective gas blanket to protect
your wine. The goal of this article is to describe
the techniques required to effectively
use inert gas to purge headspaces in order to successfully protect
your wine. First, we will detail the significance
of safeguarding your wine from being exposed to oxygen, and after 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 mixture 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 proper 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
undesireable flaws in the wine such as a diminishing
of freshness, browning, sherry-like smells and taste, and acidity production. Wines
possessing theseflaws are referred to as oxidized, since they occur upon exposure to oxygen. One
of the primary objectives in sufficient
wine aging is learning the best techniques to lower
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 possible, in order to remove headspace. Nevertheless, this technique
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 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
iseasier to compress than
liquid, it does not add a lot of pressure 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 spike in temperature, it will expand
and the subsequent 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 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 a result of the liquid contracting. Thus, if there is a chance
that your wine could face temperature fluctuations
amid 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 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 negatively react with wine. In fact, carbon
dioxide and argon actually weigh more than air, a property that proves valuable
to winemakers. Purging headspaces with either carbon dioxide or argon, when
properly carried out, can eliminate 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 effects
during its storage/aging process. The key to effectively preserving
the wine in this way is to understand the
specific techniques necessary 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 protecting purity by avoiding
turbulence. When using carbon dioxide or argon to create
[[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 determining
factor in the purity of the final volume of gas is the gas’s flow rate as it
exits the tubing. Larger flow
rates generate a churning effect that
causes the oxygen-containing surrounding air to mix in with the inert gas. If this happens, the inert gas’ ability
to protect the wine is decreased as
a result of 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 required to succeed in doing this is most
often the lowest setting on your gas regulator. Usually, this means between 1-5 PSI, depending on the tubing size.
The second step to generating a
protective inert gas blanket is to reach the highest volume
of gas that can be delivered while still maintaining the low flow-rate that is vital to avoid creating turbulence and therefore
blending the gas with the air we are trying to remove. 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 speed up the process of purging without compromising
the gentle flow necessary to creating a successful blanket, the diameter of the output tubing must be increased. 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 properly forming an inert gas blanket is to
have the gas flow parallel to the surface of the wine, or laminar, instead of directing
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. An effective and easy way to do so is to attach a diverter at the end of
the gas tubing.
To wrap up everything we have learned, the suggested
method for purging a headspace with inert gas is as follows:
First, make the adequate adjustments on the gas regulator to create
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, roughly
1-2 inches from the surface is best.
Next, turn on the gas and initiate the purging. Finally ,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 remaining in the vessel and you
should keep adding the inert gas. Keep using
the lighter test until the flame eventually goes out,
which will reveal that there is no
longer oxygen in the vessel.
Whether you’re looking for specialty gases to be used
in winemaking, other food and beverage applications, or any other industry that
utilizes specialty gases, Cee Kay Supply, Inc. has a plethora of products to meet
all of the St. Louis specialty gas needs. Cee Kay Supply, Inc. has a large
selection of specialty gases and specialty gas equipment, along with the
resources and experts on hand in St. Louis to answer your questions
and assist your needs. For more information, browse our online catalog or contact us via email at benv@ceekay.com or at 314.644.3500.