Most people have heard about the large number of applications
that call for specialty gases. From welding and
cutting, to research in laboratories, to the pharmaceutical industry, the uses
and applications of compressed gases
seem almost unending. However, less frequently
discussed is the use 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 connoisseur
or someone who likes the occasional glass at certain
events, you might not be aware that certain 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 probably spoil. In order to preserve
the wine, it is vital 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 get rid of the
oxygen. In regards to sulfur dioxide, its beneficial
uses and details about its utilization in
this process can be seen in the majority of winemaking literature. However, while these texts
may briefly discuss purging with inert gas, they frequently
do not effectively explain the actual
techniques required to perform
the application. First, it must 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 safeguard
your wine. The goal of this article is to describe
the techniques needed to properly
use inert gas to purge headspaces in order to successfully protect
your wine. First, we will discuss the significance
of safeguarding your wine from exposure to oxygen, and afterwards 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 widely known, the air we
breathe is a mixture of gases, about
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. This is because 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 subsequent changes generate
not wanted flaws in the wine such as a reduction
of freshness, browning, sherry-like smells and taste, and acidity production. Wines
containing theseunwanted
characteristics 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 ways 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
assured to resist
temperature changes, carboys and
tanks should 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
iscompressed more easily 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 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 increases 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 caused
a mess and lost wine, but your wine is now exposed to elements that could cause it to spoil. In an extreme temperature
decrease, on the other hand, the lids would be pulled inward
as a consequence 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 keep a headspace,
there is still 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 are actually heavier than air, a property that proves beneficial
to winemakers. Purging headspaces with either carbon dioxide or argon, when
properly performed, can rid
the vessel of oxygen by lifting it up and extracting
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 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 recommended to create a protective inert gas blanket. The
first step is maintaining purity by avoiding
turbulence. When employing carbon dioxide or argon to form
[[a successful|an effective|a sufficient[122] blanket, it is important
to know that the gases readily blend
with each other when moved. When trying 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. Greater flow
rates generate a churning effect that
causes the oxygen-containing surrounding air to mix in with the inert gas. If
this occurs, 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 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 necessary
to do 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 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 necessary to avoid creating turbulence and thus
combining the gas with the air we are attempting to
eliminate. While any size tubing
can applied 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 speed up the process of purging without compromising
the gentle flow required to
form a successful blanket, the diameter of the output tubing should be
made larger. One easy way to accomplish this is to fasten a small
length of a larger diameter tube onto the existing gas line on your gas regulator.
The third and final 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 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 feasible 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 adequate 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, insert 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. Then ,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 remaining in the vessel and you
should keep inserting 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 in search
of specialty gases to be applied
in winemaking, other food and beverage applications, or any other industry that
utilizes specialty gases, Delille Oxygen Company has a plethora of products to meet
all of the Columbus specialty gas needs. Delille Oxygen Company has a large
selection of specialty gases and specialty gas equipment, along with the
resources and experts on hand in Columbus to answer your questions
and assist your needs. For more information, browse our online catalog or contact us via email at scotta@delille.com or at (614) 444-1177.