By Denis Korn - who introduced the use of oxygen absorbers into the
emergency food and outdoor recreational foods industries in the early
1990's while owner of AlpineAire Foods.
Summary of key points in using an Ageless® oxygen absorber - from this article.
Z100 size is for pouches or containers quart to gallon.
Z300 size is for gallon size pouches or containers #10 can or gallon.
Z500 size is for larger pouches or 2 gallon containers.
You can use multiples of Z500 for larger containers 3 - 7 gallons.
Take out the absorbers you are going to use (within 2-4 hours
or less) - spread them out on a table or tray - reseal or pack the
remaining absorbers in the master bag (if you have an impulse
sealer or other appropriate sealer), or another high barrier film
pouch (like a food saver), or container (without the proper pouch
sealer, many people use an appropriate size mason canning jar with an air
tight lid - packed tight) - DO NOT USE ZIP LOCK BAGS.
Use the absorbers you have within 6 months to 1 year.
Be aware of the gas barrier transmission rates of the
containers you are using - rigid metal and glass have a zero transmission
rate for both vapor and gas. The type of material you use
will determine how long it retains an oxygen free atmosphere.
The seal must be air tight.
Foil laminated pouches - currently called "mylar pouches - a misnomer" are NOT recommended for long term storage (10+ years) as they can contain microscopic pin-holes that will eventually transmit oxygen.
For complete instructions and information, it is highly recommended that you read the entire article below.
At that time the goal to
achieve for the canning of shelf-stable dried foods was a residual oxygen level
of 2% or below.
This was the level
required by military specifications for long term foods.
Oxidation and an atmosphere inhibiting
microbial growth were significantly reduced at these low levels.
The military specified the #10 can for their
long term storage of dried products.
By
utilizing the appropriate size oxygen absorber, the residual oxygen levels
could be reduced to 0.1% or less - a significant drop in oxygen levels.
The premier manufacturer of
oxygen absorbers, and the one I use, is Mitsubishi Gas Chemical Company, Inc.
which produces the Ageless® brand oxygen absorber.
While there are numerous types of absorbers
for varied packaging conditions, the appropriate Ageless® absorber for use
with dried foods is type Z.
It is important to note that
oxygen absorber sachets were designed to be used by industrial manufacturers
and packers of food products with the necessary expertise in working with the
absorbers.
While simple to use, if not
handled properly or sized correctly you have wasted your time and money and
have not achieved the expected outcome.
I have seen and heard of numerous situations where individuals have inappropriately
utilized oxygen absorbers and they will unfortunately not accomplish the
results anticipated.
If you are going to
use these devices, I recommend following the instructions in this article and
talk to those who are educated in their
proper use.
Why use an
oxygen absorber?
There are essentially two
reasons one would use an oxygen absorber - the prevention of oxidation, and the
prevention of food damage by infestation.
This of course helps to increase the shelf life of most foods one
chooses for food storage.
Infestation is
addressed further on in this article.
Oxidation is responsible for
the deterioration of foods including the loss of flavor and taste,
discoloration, deterioration and rancidity of fats and oils, texture change,
and nutritional loss.
Some foods are
more susceptible to oxidation deterioration than others.
It is important to know how susceptible the
foods
you are storing are to oxidation, because as you will see the type
of container you store your foods in may at some point no longer be an adequate
oxygen barrier.
Unfortunately the issue
of keeping foods in an oxygen free environment is not easily understood by the
do-it-yourself preparedness planner.
There is so much misinformation, speculation, confusion, and factual
error that the average planner is at a disadvantage in learning the proper
techniques.
Hopefully this article,
others written by Denis Korn, and careful research by the preparedness planner
of trustworthy sources, will produce reliable results.
Determining
the size of oxygen absorber
Depending upon the container
size and the void area (the area that is the space between the food item) in
that container, a number of different sized Ageless sachets are available from
size 20 to 2000.
IMPORTANT: Ageless®
assigns their sizes with numbers that correspond to the oxygen
absorption
capacity
in milliliters (ml) - this is the actual amount of oxygen that
can be absorbed by the sachet.
Other
companies may designate their sizes by the
equivalent air volume in
milliliters - this is the total air volume you have in the void area that
includes oxygen, nitrogen, and a very small amount of other gases.
These are two different figures that it is
important for you to know.
After you ascertain the void
area of your container you will have determined the
equivalent air volume.Since oxygen is approximately 20% of the
normal air volume, divide the equivalent air volume by 5 and you get the
absorption
capacity
of each size sachet.An
Ageless® Z100 will absorb 100 ml of oxygen which is contained in 500ml of air
volume. For your information 1 gallon equals 3,785.4 cubic centimeters.
Obviously a food item that
has a large volume or irregular size will produce a larger void in a container - dried mushrooms, large beans, and certain dried vegetables would be an
example of this.
The void in a container
of powders, flours, small grains, and beans would be less.
In general, camping food
pouches would use a Z30 or Z50, a #10 can or gallon pouch a Z300 and a 5 to 6 gallon
bucket a Z1000, Z2000 or 2 or 3 Z500 depending on the size of the food products and the void
area.
Because only oxygen is
absorbed there will of course still be in the container an approximately 80%
inert nitrogen atmosphere.
This will
cause a partial vacuum effect meaning that pouches will shrink slightly and
become more compact, and in buckets there will be concave effect - top and
sides will move slightly inward.
Advantages
of an Ageless® oxygen absorber (and other quality absorbers)
Reduces oxygen in an
airtight container down to 0.1% or less to prolong a product's shelf life.
It prevents oxidation and
mold, bacteria, microorganisms, insect infestation and the like, which thrive
in an oxygen-rich packaging environment.
Done properly, it is simple
to use.
Keeps food products from
losing their freshness, color, taste, flavor, wholesome goodness, and important
nutritional value when exposed to oxygen.
Conventional preservatives,
antioxidants, gas flushing, and vacuum packing often are not effective because
they do not completely eliminate oxygen.
Conventional and artificial
preservatives may be undesirable to many and may produce adverse health
affects.
The oxygen absorber is safe
to use.
They have been tested and found
to be practically non-toxic.
The LD50
Value of the contents is safer than salt.
The major component of Ageless® is powdered iron oxide, an odorless material that in its sachet has
no effect on the foods in the container.
The sachet can be discarded
through ordinary disposal methods, with no special treatment required.
Selection
of a packaging container for use with an oxygen absorber
Of all the issues relating
to the use of oxygen absorbers this is the most confusing and misrepresented
among the do-it-yourself group.
Remember
absorbers were designed with specific instructions for use by manufacturers and
commercial packers.
Points to consider:
Oxygen absorbers were
designed to work when inserted into cans, bottles, and film that offer a
variety of airtight characteristics.
When using cans, make sure
there is no leakage along seams.
While
this container is not as practical to use for the do-it-yourself group, it is
without a doubt the most reliable.
Glass bottles should have a
tight seal between the bottle and closure.
Film pouches must be
designed to have a negative to very low oxygen permeability.
Films have both an oxygen
and vapor permeability rating.
The permeability or rate at
which oxygen is transmitted through a film or material determines the length of
time the container will remain oxygen free.
The permeability of rigid metal
and glass is zero.
It is the seams and
closures that determine any leakage.
The permeability of aluminum
foil can be zero or have a measurable transmission rate depending on the thickness and quality of the foil.
There are hundreds of
combinations of various films for pouches.
No single barrier material is adequate for a pouch; it requires a
combination of barrier materials to be laminated together.
Film materials with the
proper barrier characteristics must be laminated together to create a pouch
that will have a low permeability for an oxygen absorber to work properly.
A pouch with an aluminum
foil barrier as one of the layers is the best.
Pouches with evaporated or
coated aluminum are not as good as solid foil.
While there are various
plastic and nylon barriers that have a low permeability, they all will
eventually allow the transmission of oxygen and the oxygen levels in the
pouches will increase.
The oxygen absorber can only
absorb so much oxygen and it too has a limited shelf life.
A general rule of thumb for
a
non-solid foil, laminated, high barrier pouch is a 3 year barrier
viability life.
Low barrier pouches have a
viability of 3 to 6 months depending on the film material.
Think "mylar" balloons filled with helium.
A laminated pouch with a
solid foil barrier is generally recommended for between 5 and 10 years.
Here is the issue with
pouches
Inadequate or faulty seams and rough handling can cause what is known
as pin-holing or seam breakage.
The
pouch has lost its integrity and its low permeability rate has been
compromised.
Excessive folding and
squeezing pouches into buckets, too much handling, too much weight on a pouch,
sharp food products within the pouch poking through, and more, can contribute
to large or even minute holes and tears.
Pouches with oxygen absorbers, for the longest possible shelf life,
must be stored and handled properly.
Also keep in mind, because
the container now has an oxygen absorber, an atmospheric pressure differential
has been created (this is the tendency for the inside pressure to want to be equalized
to the outside pressure).
This means
there will be an extra "pulling effect" on the seams and closures of the
containers to absorb the outside atmosphere.
This is another reason for proper handling.
Plastic buckets and oxygen
absorbers
While plastic buckets are
much thicker (70 to 90 mil) than plastic laminated pouches, they are still
plastic (high density polyethylene).
Oxygen will
eventually be transmitted through the bucket.
Depending upon the thickness and seam stability of the bucket the
general rule would indicate a 3 to 5 year barrier viability life
. This means that in this period of time the atmosphere inside the bucket has equalized with the atmosphere outside the bucket. Plastic bucket seams are susceptible to the "pulling effect" mentioned above and can cause oxygen seepage into the
container.
Also, depending upon the environment,
plastic buckets will eventually absorb moisture and odors.
TAKE NOTE: Without proper
testing and industrial controls, residual oxygen levels in do-it-yourself
packaging are - assumption, speculation, guessing, and probability!
If you have access to equipment that tests
residual oxygen levels in your container you may want to consider some spot
checking.
How to use
an oxygen absorber
Using an oxygen absorber is
relatively easy.
Make sure you are aware
of all the procedures and characteristics of storage, sizing, containers,
handling, and other fine points covered in this article.
It is economical and safe to use oxygen
absorbers that offer an option to creating an oxygen-free environment that
helps to improve shelf life.
Simply put your food in a
high gas barrier film package, metal can, or glass bottle; put the appropriate
size absorber in the container; and seal the container properly.
Points to consider:
Depending on the size of absorber
used it will take 1 to 4 days to have produced an oxygen free (<0.1%)
atmosphere.
Absorbers are packed in
master high barrier bags of various quantities depending on their size.
Check the tightness of the vacuum packed
master bag.
If you hang the master bag
from one end, the packets should not slip.
If they do, do not use that master bag.
After opening the master
bag, spread out the needed quantity of packets.
The sachets that are not used should be resealed in a master bag or discarded
if their exposure to air exceeds
4
hours - try to reseal unused absorbers sooner
.
Remaining sachets should be
resealed in the master bag, or another high barrier film pouch or container,
after pressing out the air.
A well
sealed proper size glass mason jar container will work.
Do not pile up absorbers in
the open tray or holding container while waiting to insert in your container.
This may
cause excessive heat build up.
Do not remove and use an absorber
one by one leaving the master bag open.
Handle master bags properly
and store in a cool (below 85 degrees [F]) and dark place.
Do not use zip-lock plastic
bags or other flimsy containers to store unused absorbers.
Ideally, if you obtain your
absorbers while relatively fresh, use them no later than 6 to 12 months after
receipt.
Prevention
of damage by microorganisms (mold and aerobic [oxygen dependent] bacteria),
insects, worms, and their eggs
By producing an oxygen-free
(<0.1% for the Ageless® absorber) environment, live organisms can not live
and grow and are eradicated.
Oxygen absorbers prevent the
growth of microorganisms.
The oxygen-free packaging
allows you to prevent both adult insects and their eggs from spoiling and
damaging foods.
Testing that utilized the
Ageless absorber found that all of the eggs, larvae, pupae, and grown insect of
the Rust-red flour beetle, Weevil, Azuki weevil, and Almond moth were killed
within 14 days - at 77 degrees (F).
The
proper container with a zero to very low permeability rate and no holes or seam
damage must be used.
Questions
and Answers about the Ageless® oxygen absorber from their brochure (may apply to
other absorber brands also)
1)Can absorbers be used at low temperature?
-Lower temperatures slow oxygen absorption rates.However, since product deterioration usually
slows down at low temperature while activity of microorganisms also slows down, slower oxygen absorption does not create a problem.
2)Can absorbers be used with vacuum packages?
- Since the amount of air is already decreased in a
vacuum package, a smaller size absorber can be selected.
In the case of a strong vacuum ratio, place
the absorber into a free air-flow stream, with some distance between the
product and packaging film.
You use an
absorber even in a vacuum package because not all vacuum packing can reduce the
residual oxygen as low as an absorber can.
3)Can absorbers be used with gas flushing packaging?
- Absorbers can be used with a nitrogen gas replacement
system.
However, this combination will
result in a slow rate of oxygen absorption due to the low initial oxygen
concentration; therefore, select a larger size absorber to compensate for the
delay in oxygen absorption.
In addition,
gas replacement will tend to result in a fluctuating replacement rate.
This is another reason to use a larger size
packet.
Carbon dioxide gas replacement
and mixed carbon dioxide-nitrogen gas replacement are
not recommended
for use with absorbers, as carbon dioxide will inhibit oxygen absorption.
4)Will the deoxygenation rate be affected by the
location in which the
absorber is
placed in the container?
- Yes.Generally, an absorber will eliminate oxygen more quickly when placed
directly on the product.
If available,
testing will indicate the best location for an absorber.
5)Sometimes absorbers will heat up during production
packaging - is this normal?
- If the master bag containing a self-reacting type of
absorber is left open, or if the individual packets are taken one by one from
the master bag, heat generated from the reactions of the absorber may
accumulate in the bag, causing the bag to feel hot.
Always spread out the packets on a tray to
avoid decreased performance.
As stated
above, 4 hours is the maximum time a Z type (for dried foods) Ageless packet
should be exposed to the room atmosphere.
6)I use only a small quantity of absorbers at a
time.
Will opening and closing the
master bag affect the performance of the absorber?
- Repeated opening and closing of the master bag is not
desirable, as it will cause the absorber to repeatedly come into contact with
air.
We recommend that you divide the
packets into small quantities and place these bags, constructed from a high
gas barrier material, so as to reduce the frequency of contact between the
absorber and the atmosphere.
The information contained in
this article is general and should not take the place of the user's own
application tests.
Conditions of use
vary depending on the specific applications of each user.
The user is responsible for the proper
calculations and techniques of absorber application.
