Chapter 3 – Do-it-Yourself Food Storage

WHAT IS FOOD GRADE PACKAGING?

Q:  OK, I’m ready to start my storage program.  What should I put the food in?

A:  You should use food grade packaging for storing anything you intend to eat.  A food grade container is one that will not transfer noxious or toxic substances into the food it is holding. If you are uncertain whether a package type is food grade you can contact the manufacturer.  Ask if that particular container is (US) FDA approved meaning that it is safe for food use.  When inquiring be sure to specify the characteristics of the food you are storing; wet, dry, strongly acidic or alkaline, alcoholic or a high fat content.  A container that is approved for one of the above types of food may not be approved for another.

The major functions of a food storage container are to:

#1. Protect its contents from outside environmental influences such as moisture, and oxygen, but possibly also heat or cold, light, insects and/or rodents as well.

#2. Prevent damage during handling and shipping.

#3. Establish and/or maintain microbiological stability.  The container should not allow microorganisms such as fungi and bacteria from outside the container to come into contact with its contents.  This is of critical importance to wet-pack foods such as canned vegetables, fruits and meats.

#4. Withstand the temperatures and pressures it will be exposed to.  This is necessary if the contents are to be pasteurized or sterilized, either immediately before or after filling.  It must not have any structural failures nor release any noxious or toxic breakdown chemicals into the food it contains.  This is the reason why purpose built canning jars are recommended for home canning and mayonnaise jars aren’t.  The former are made heavier to withstand high temperatures and handling whereas the latter are not and have an increased risk of breakage if used for that purpose.

Virtually all containers used in home food preservation involving exposure to high temperatures are made of glass or metal, with the exception of some specialized “heat & seal” type of plastic bags.  Glass can be used with any food type providing it is clean and in sound condition but the lids, particularly the liner inside the lid, may not be so you’ll need to investigate suitability.

Metal cans are more specialized.  They must be intended for food use and must also have a lining or coating of the inside that is suitable for the pH level of the food it will be in contact with.

If the foods are not subjected to some form of heat processing before or after packaging your selection of container types for home use is a great deal larger.  Virtually any kind of clean, sound glass jar can be used and many types of new metal containers.  Several sorts of plastics have become popular.  These various kinds of plastics are each suited for different purposes, making selection a more complex task.

WHERE DO I FIND FOOD GRADE CONTAINERS?

Food grade packaging is everywhere.  Every time you go into the grocery store you are surrounded by it.  Many well known companies such as Tupperware and Rubbermaid manufacture and sell empty packaging for the express purpose of containing repackaged foods.  The kinds of containers you are interested in and the types of foods you want to put in those containers will dictate where you need to look for a particular packaging system.

For food storage purposes most folks are usually interested in five and six gallon plastic pails, certain recycled plastic containers such as soda or juice bottles, glass jars from half pint to gallon sizes, metal containers such as the institutional sized #10 cans, and Mylar or other high barrier property plastic bags.  Those are the containers most often used, but virtually anything that can protect foods from outside environmental influences, safely contain something you’re going to later eat and have a volume capacity large enough to be worthwhile may be used.

A number of food storage retailers such as those listed in the Resources section sell plastic buckets, Mylar bags and a few even sell new #10 cans with lids.  It may also be possible to purchase #10 cans through the LDS Family Canneries and dealers such as Lehman’s Hardware, Cumberland General Store or Home Canning Specialty and Supply.  On the local scene, plastic five gallon buckets are widely available, but only if you purchase them through a company catering to a food related trade will you likely be able to tell if they’re safe to keep food in. If you can locate a customer service number for the manufacturer of a container that interests you call them and ask.  Many times manufacturers will make products that are FDA approved and sell them as general purpose containers, but you need to ask to be sure.

Packaging supply houses have large FDA approved packaging lines.  Several such companies are listed in the Resources section and a bit of detective work will certainly turn up more.  Some require minimum orders and others don’t.  The cost of shipping the containers will probably play a major role in your decision making.  If you are going to package a great deal of food all at once, perhaps for a group, some of the companies that require minimum purchases may save you a fair amount of money and supply packaging you might otherwise have a difficult time finding. Some time spent searching the Thomas Register, available both online (http://www.thomasregister.com) and in library reference sections, might turn up some valuable leads.

For glass jars, don’t overlook flea markets, yard sales, thrift shops and similar places.  Canning jars can sometimes be had for very little.  Delicatessens, sub shops and restaurants of all sorts can be a source of one gallon glass jars formerly containing pickles, peppers, etc.  If the lids are still in good condition, they are well suited to bulk storage and can be reused over and over.  When I need new buckets I go to a neighboring town to buy them from a beekeeping supply house which sells them for bulk honey storage.  A bit of looking will turn up other potential sources as well.

Metal cans, by and large, are not reusable for food storage, but some companies might be able to sell you new cans.  The traditional single use #10 can is only the beginning of what might be available with a little looking.  Gallon sized or larger cans with double friction lids (like paint comes in) make excellent storage containers and some companies make them food  safe.  One gallon and larger cans with wide diameter screw caps are available from some companies as well.  You might have seen some of these holding edible oils, soy sauce, honey and other liquid food.  If they come with a cap that will seal air tight they would be well suited for bulk storage of grains and legumes, particularly if they come in a four to six gallon size.

Pick up your local phone book, log on to your favorite search engine or head to your local public library and explore the possibilities.  Make it clear that what you want must be FDA approved and be up front about how many you need or can deal with.  If one company won’t deal with you, try another. You’ll eventually get what you want.

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From: Denis DeFigueiredo ddefig@newhall.com
Originally posted in: rec.food.preserving

I called Berlin [eds. note, a plastic container mfgr.] 1-800- 4-BERLIN and spoke to them, plus an outfit called Kirk Container (they manufactured some 5 gallon paint buckets I saw in the local hardware store).  Both places said that buckets made from High Density PolyEthelene (HDPE) are approved for food.  It has to do with the possibility of interaction between any chemicals in the food and the plastic.  As it turns out, Kirk manufactures only one kind of bucket, and then markets it for paint, hardware, food, etc.  The price is right on the “paint buckets” – much cheaper than the local restaurant supply house.

High density polyethelene buckets will have HDPE stamped on them, or a recycle symbol with a “2” in the middle.

DISCLAIMER: I’m only passing on information I received from the manufacturers. I am in no way professing these things to be absolute fact!

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From: “Jenny S. Johanssen” johanssen@matnet.com
Originally posted in:  rec.food.preserving

Denis – saw your comments on food grade buckets and thought I’d offer my solution.  My son cooks at a local Mexican restaurant.  They get all their strawberries (for the strawberry magaritas at the bar) in 3 gallon plastic buckets.  Now you know how many margaritas pass through a Mexican bar each night – lots.  So I asked my son to save me some buckets.  They are ideal for storing flour, rice, I made (from my home grown raspberries) a delicious raspberry cordial in one of the buckets, another I made Raspberry wine in.  My motto is why buy when you can recycle! Thanks for giving me the time and space to add my two-bits worth. –  Jenny

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From:  Woody Harper lager@primenet.com
Originally posted: rec.food.preserving

…I get topping buckets from Dairy Queen and I have to make sure there is no trace of the strawberry syrup left.  A little detergent and elbow grease followed by a chlorine solution bath keep everything nice and clean.–

PLASTIC PACKAGING

Before we can discuss plastic packaging it is necessary to understand what is the substance we call “plastic.”  Plastics are produced from basic polymers called “resins”, each of which have differing physical properties.  Additives may be blended in for color or to modify particular properties such as moldability, structural rigidity, resistance to light or heat or oxidation. Additionally, it is common for several different kinds of plastic to be laminated together each performing a particular desired task.  One might offer structural rigidity and the other might be more impermeable to the transfer of gasses and odors.  When bonded together a rigid, gas impermeable package can be made.

Whether that package is safe for food use will depend on the exact nature of the additives blended into the plastic.  Some of them, notably plasticizers and dyes, can migrate from the packaging material into the food it’s containing.  This may be exacerbated by the food it’s in contact with especially if it is high in fat, strongly acidic, or alcoholic in nature.  Time and temperature may also play a prominent role in the migration of plastic additives into food.  For this reason, the (US) FDA assesses the safety of packaging materials for food contact and conducts toxicological studies to establish safety standards.  Only plastics that are FDA approved for a particular food type should be used for direct contact with that food.

Being FDA approved, however, may not be all of the story.  It must still be determined whether the particular plastic in question has the physical properties that would make it desirable for your purpose.

As mentioned above each base resin has somewhat differing physical properties that may be modified with additives or combined by laminating with another plastic or even completely unrelated materials such as metal foils.  An example of this is “Mylar”, a type of polyester film. By itself, it has moderate barrier resistance to moisture and oxygen. When laminated together with aluminum foil it has very high resistance and makes an excellent material for creating long term food storage packaging.  One or more other kinds of plastic with low melting points and good flow characteristics are typically bonded on the opposite side of the foil to act as a sealant ply so that the aluminized Mylar can be fashioned into bags or sealed across container openings. The combined materials have properties that make them useful for long term storage that each separately do not have.

The most common plastic that raises suitability questions is High Density PolyEthylene (HDPE).  It’s used in a wide array of packaging and is the material from which most plastic five and six gallon buckets are made.  It has a moderate rigidity, a good resistance to fats, oils, moisture and impacts, a fair resistance to acids, but is a relatively poor barrier to oxygen.

Whether it is suitable for your purpose depends on how sensitive to oxygen your product is and how long you need it to stay in optimal condition.  Foods such as whole grains are not particularly delicate in nature and will easily keep for years in nothing more than a tightly sealed HDPE bucket.  Most legumes are the same way, but those that have high fat contents such as peanuts and soybeans are more sensitive to O2.  Other foods such as dry milk powder might only go a year before deleterious changes are noticed.   If that milk were sealed in an air-tight aluminized Mylar bag with the oxygen inside removed, the milk would keep for much longer.  Better still would be to seal the milk in a metal can or glass jar.  HDPE alone can be used for long term storage with one or more of the following precautions to keep a high food quality:  The food should either be put on a shorter rotation cycle than packaging also using a second gas barrier such as Mylar; be periodically opened and re-purged or fresh absorbers should be inserted.

Another common plastic used in food storage is polyethylene terephthalate commonly known as PETE or PET plastic.  Used to make soda, juice, and some water bottles among other products it is available for recycling into food storage containers in nearly every home.  Properly cleaned and with intact screw-on lids PETE plastic containers will serve for keeping nearly any kind of food providing the containers are stored in a dark location.   PETE has good barrier properties against oxygen and moisture and when used in combination with oxygen absorbers presents a complete dry-pack canning system in itself.  About the only drawbacks to PETE plastics are that they are nearly always transparent to light, container volumes typically are limited to a gallon or less, and when used in conjunction with oxygen absorbers the sides will flex sufficiently to make stacking difficult though you could simply lay them on their sides.

There are other plastics and plastic laminates with good oxygen and moisture barrier properties that are suited for long term food storage, but they are not as easy to find, though some used containers might be available for reuse.

A.2.1  HOW DO I GET THE ODOR OUT OF PICKLE BUCKETS?

I’ve had fairly good luck doing it in the following way.  As vinegar is the primary smell in pickles and it’s acidic in nature, we use a base to counteract it.  First we scrubbed the bucket well, inside and out, with dish detergent, most any sort will do. Then we filled the buckets with hot water and dissolved a cup of baking soda in each.  Stir well, get the bucket as full as you can and put the top on.  Put the bucket in the sun to keep it warm so the plastic pores stay open as much as possible.  In a couple of days come back and empty the buckets. Rinse them out, fill with warm water again and add about a cup of bleach and reseal.  Put back in the sun for another couple of days.  Empty out and let dry with the tops off.  We completely eliminated the vinegar smell this way.  It might be possible to cut the time down a lot, but we haven’t experimented that much.

METAL CANS

Metal cans and glass jars being heat resistant, can both be used for heat processed, wet-pack foods and for non-heat treated dry pack canning.  Relative to glass jars though, metal cans have several disadvantages for the do-it-yourselfer.  They are hard to come by, and they need specialized equipment to seal them that can be difficult to locate.  The greatest flaw which makes them unpopular for home canning is they can only be used once.  As the commercial canning industry is not interested in reusing the containers, metal cans make great sense for their purposes.  The cans are both cheaper (for them) and lighter than glass jars.  This adds to the economy of scale that makes canned foods as cheap as they are in the grocery store.

For home canning, glass jars are better because even the smallest of towns will usually have at least one business that carries pressure and boiling water canners along with jars, rings and lids.  With metal cans a sealer is also necessary which usually has to be ordered from the manufacturer or a mail-order distributor.  A few of which are listed in the Resources section.

Tin cans are not really made of tin.  They’re actually steel cans with a tin coating on the inside and outside.  Some kinds of strongly colored acidic foods will fade from long exposure to tin so an enamel liner called “R-enamel” is used to forestall this.  Certain other kinds of food that are high in sulfur or that are close to neutral in pH will also discolor from prolonged contact with tin.  For those foods, cans with “C-enamel” are used.

The excellent food preservation book, Putting Food By Chapter 6 (see reference list) has a section on the use of metal cans for wet packed foods as does the Ball Blue Book.

Probably the most common use of metal containers is the #10 cans such as are used by the LDS Family Canneries discussed below. This is not the only way metal containers may be used though.  It will probably take a bit of searching, but there are various food grade metal containers available of sufficient volume to make them useful for food storage. They usually have double friction lids similar to paint cans or screw caps like jars that can achieve an air-tight seal.  If you can find them with a sufficient volume capacity they can be of real use for storing bulky foods such as grains, legumes and sugar.  Smaller cans of a gallon or less would be useful for storing items like dry milks.  If properly sealed, metal cans have a far higher barrier resistance to gasses such as oxygen, CO2, and nitrogen than any plastic.

Although they can hardly be considered portable the use of clean metal drums (not garbage or trash cans), either themselves food grade or used with food grade liners, is also a possibility.  A fifty five gallon drum of grain will weigh several hundred pounds, but may make for a much easier storage solution than multiple buckets.  The advantage of using such a large container is that a great amount of a single product can be kept in a smaller amount of space and fumigating or purging the storage atmosphere would be simpler.  The disadvantages are the difficulties of moving it and rotating the stock in the drum.  If using oxygen absorbers make sure the drum you want to use is capable of making an air-tight seal, otherwise you should stick with carbon dioxide fumigation.

POOLING RESOURCES:  THE CHURCH OF JESUS CHRIST OF LATTER DAY SAINTS — THE MORMONS

(Please note, Captain Dave has heard that the information in this section is no longer accurate.  Please do a  little research locally and check it out before you take it for granted.)

Although the purchase of a can sealer and metal cans for home use is not generally economically feasible for most people there is one method by which it can be made practical.   This is by pooling community resources to purchase the equipment and supplies.  It may even not be necessary to form your own community to do this.  If you live in the right area your local Latter Day Saints church may have facilities they will allow you to use. They may even have suitable food products to sell you.  This is an offshoot of the church’s welfare programs and is done in their Family Canneries also known as Home Storage Centers.  Rather than using plastic buckets they have gone over to using metal cans and aluminized Mylar bags church-wide for dry-pack canning.  By sharing the cost of the equipment and purchasing the cans in bulk quantities, they are able to enjoy the advantages of metal cans and professional equipment over plastic containers while minimizing the disadvantages of cost.

— Please see VI.D.1 Organizations. The Church of Jesus Christ of Latter Day Saints — LDS Family Canneries for more information about where LDS Family Canneries may be found and how best to approach using them. —

Any food products you want to have sealed in cans or pouches will need to fall within the LDS cannery guidelines of suitability for that type of packaging.  This is for reasons of spoilage control as many types of foods aren’t suitable for simply being sealed into a container without further processing.  If you purchase food products from them, they will already be within those guidelines.  A brief treatment of these guidelines may be found in VI.D.1 LDS Family Canneries Guidelines.

Once you have your foodstuffs on hand, either supplying your own or by purchasing them from the cannery you’re ready to package them.  It is here that using some forethought concerning your packaging system can save you much time and aggravation.

IMPORTANT NOTE: Please keep in mind that the individuals responsible for the family canneries are all volunteers with demands on their time from many areas.  Be courteous when speaking with them and, if there are facilities for use, flexible in making arrangements to use them.  You will, of course, have to pay for the supplies that you use, cans and lids at the least, and any food products you get from them.  As a general rule they cannot put your food in storage for you.  Be ready to pay for your purchases in advance.  They do not take credit cards and probably cannot make change so take a check with you.

The following is a list of suggestions to make the most efficient use of your access time:

#1 – Make your appointment well in advance.  If you are a non-LDS member be sure to ascertain whether you are allowed to use the facilities. Possibly you may be able to go with a church member if you cannot go for yourself alone.  Many people may be trying to make use of the canneries so making advanced reservations is a must.

#2 – Have enough people to set up an assembly line type operation.  Make sure each of your people knows what they need to do and how to do it.  At least four people for any serious amount of food is a good number.  Ask the cannery volunteer to go over the process with you and your crew.

#3 – Make sure you have enough muscular helpers to do the heavy lifting so you don’t wear yourself out or hurt your back.  Some of the supplies you will be working with, such as wheat, come in fifty pound bags and a box of #10 cans or pouches full of sugar or other weighty food is heavy.

#4 – Make labels in advance for any foods you bring with you to pack that the cannery does not carry.  This will save time and possibly much confusion after the cans or pouches are filled.  Once sealed one anonymous looking can or pouch looks like another.

#5 – Take out only as many as oxygen absorbers as you will use in fifteen minutes.  They use most of their adsorptive capacity within two to three hours depending on temperature and humidity so you don’t want to waste any by soaking up the oxygen in the room.  The ones you don’t use right away should be tightly sealed in a gas proof container.

#6 – Save powdery food items such as dry milk powder, pudding mixes, grain flours and meals till last.  They can be messy to can and this will keep them out of your other foods.  Dust masks may not be a bad idea.

#7 – Leave time to clean up after yourself.  The cannery is doing you the courtesy of allowing you to use their equipment and selling you the supplies at cost.  You should return the favor by leaving the place at least as clean as you found it.  If they give you a set amount of time to work in then finished or not honor that time slot.  Others may be waiting to use the equipment too.

#8 – Always keep in the back of your mind how much volume and weight your vehicle can haul.  You’d hate to find you had canned more than you could carry home.

PREVENTING EXTERIOR CORROSION OF CANNED GOODS

Some areas have difficulty storing metal canned goods for long periods of time.  This is usually caused by high humidity or exposure to salt in a marine environment.  If this is a problem, it is possible to extend the life of metal cans by coating their outsides. I’ve seen this used on boats here in Florida, especially when loading for a long trip.  There are at least five methods that can be used to do this, but for cans that require a can opener only the paraffin or mineral oil methods should be used.

PARAFFIN METHOD:  Using a double boiler, paraffin is melted and brushed on the clean, unrusted cans.  Be certain to get a good coat on all seams, particularly the joints.  If the can is small enough, it can be dipped directly into the wax.  Care must be taken to not cause the labels to separate from the cans.  Do not leave in long enough for the can contents to warm.

MINERAL OIL METHOD:  Use only food grade or drug store (medicinal) mineral oil.  Wipe down the outside of each can with only enough oil to leave a barely visible sheen.  Paper labels will have to be removed to wipe underneath with the contents written on the outside beforehand with a marker or leave the under label areas uncoated.  Even with a barely visible sheen of oil the cans will tend to attract dust so you will need to wipe off the can tops before opening.

PASTE WAX METHOD:  Combine 2-3 oz. of paste or jelly wax with a quart of mineral spirits.  Warm the mixture CAREFULLY in its container by immersing it in a larger container of hot water.  DO NOT HEAT OVER AN OPEN FLAME!  Stir the wax/spirits thoroughly until it is well mixed and dissolved.  Paint the cans with a brush in the same manner as above. Place the cans on a wire rack until dry.

SPRAY SILICONE:  A light coating of ordinary spray silicone may be used to deter rust.  Spray lightly, allow to dry, wipe gently with a clean cloth to remove excess silicone.

CLEAR COATING:  A clear type of spray or brush on coating such as Rustoleum may be applied.  This is best suited for larger resealable cans, but will keep them protected from corrosion for years.

GLASS JARS

Compared to metal cans, glass jars are very stable, although they obviously don’t take being banged around well.  Fortunately the cardboard boxes most jars come in are well designed to cushion them from shocks.  The box also has the added bonus of keeping damaging light away from food.

The major advantage of glass jars is they are reusable.  For wet-pack canning the lids should be replaced, but the rings can be reused until they finally rust away or become too dented to use.  For dry pack canning even the lids may be reused nearly indefinitely if you’re careful in removing them.  In my personal experience I’ve grown to prefer Ball lids rather than Kerr, especially for vacuum sealed dry pack canning.  The red sealing compound Ball uses seems to more reliably achieve a seal than the gray compound Kerr uses.

When you get right down to the bottom line, it is seldom practical strictly in terms of dollars and cents to wet-pack your own food in jars.  When you count the cost of your equipment, including the jars, rings, lids and all the rest, along with a not inconsiderable amount of your personal time, the cost of purchasing or growing your produce, you’ll almost always come out ahead to buy food canned for you by the commercial canning industry.  That said, forget about the strict bottom line and examine more closely why you want to put up your own food.  For many, gardening is a pleasure and they have to have something to do with the food they’ve grown!  There’s also the fact that for many, you simply cannot buy the quality of the food you can put up for yourself.  The canning industry tries to appeal to a broad spectrum of the general public while you can put up food to your own family’s specific tastes. Home canning is not so much about saving money as it is about satisfaction.  You get what you pay for.

If home canning appeals to you, please allow me to point you toward the rec.food.preserving FAQ where much good information about methods and techniques may be found.

Dry-pack canning using glass jars, on the other hand, may well make a great deal of economic sense.  It is usually far cheaper per pound to purchase dry foods in bulk quantities, but often unsuitable to store it that way.  Breaking the food down into smaller units allows for easier handling and exposes a smaller quantity to oxygen and moisture before it can be eaten.  Of course, packaging used for doing this can be made of many different materials, but glass is often the easiest and most convenient to acquire and use.  Used containers are often free or of little cost.  One source of gallon sized glass jars are sandwich shops and restaurants that use pickles, peppers and other sandwich condiments.  There are also half-gallon canning jars, though they are sometimes difficult to find.  Both Ball and Kerr make these jars and I have a local Ace hardware order mine.

MYLAR BAGS

The word “Mylar” is a trademark of the DuPont corporation for a special type of polyester film.  Typically made in thin sheets, it has a high tensile strength and is used in a wide variety of industrial settings.

In food storage, particularly for the long term, it is commonly found as a laminate with Mylar as the top layer, a very thin aluminum foil in the middle and one or more other types of plastic films on the bottom acting as sealant plies.  This laminate combination possesses a high resistance to the passage of oxygen, carbon dioxide, nitrogen, other gasses, water vapor, and light which is what makes it valuable for our purposes.  Unfortunately, it has a poor puncture resistance so must be used as an interior liner for more puncture resistant containers rather than as a stand-alone package.

Food grade aluminized Mylar complies with US FDA requirements and is safe to be in contact with all food types except alcoholic.

For food use, Mylar is most commonly available as pre-made bags of various sizes.  Flat sheets or rolls of the material might also be found from which bags could be fashioned as well.

When Mylar bags are used by the storage food industry they are generally for products sealed in plastic buckets.  The reason for doing this is the High Density PolyEthylene (HDPE) from which the pails are made is somewhat porous to gasses.  This means that small molecules, such as oxygen (O2), can slowly pass through the plastic and come into contact with the food inside.  The problem is further compounded if oxygen absorbers are used, as the result of their absorbing action is to lower the air pressure inside the container unless it has first been carefully flushed with an inert gas such as nitrogen.  How fast this migration activity will occur is a function of the specific plastic formulation, its wall thickness and the air pressure inside the container.  In order to gain the maximum possible shelf life a second gas barrier, the Mylar bag, is used inside the pail.

Whether the use of these bags is necessary for your home packaged storage foods depends on how oxygen sensitive the food item is and how long you want it to stay at its best.   If the container is made of a gas impervious material such as metal or glass then a second gas barrier inside is not needed.  If it is HDPE or a plastic with similar properties and you want to get the longest possible storage life (say 10+ yrs for grain) then Mylar is a good idea.  If you’re going to use the grain in four to five years or less then it is not needed. Provided the oxygen has been purged from the container in the first place, either with a proper flushing technique, or by absorption, there will not have been sufficient O2 infiltration to seriously impact the food. Particularly oxygen sensitive foods such as dry milk powders that are to be kept in plastic containers for more than two years would benefit from the use of Mylar.  Naturally, storage temperature and moisture content is going to play a major role as well.

There is also the question of the seal integrity of the outer container.  If you are using thin walled plastic buckets in conjunction with oxygen absorbers the resulting drop in air pressure inside the pail may cause the walls to buckle.  If this should occur, there would be a risk of losing seal integrity, particularly if the buckets are stacked two or more deep.  If the food was packed in Mylar bags with the absorbers inside this would keep the vacuum from seriously stressing the container walls.  Better still would be not to have the problem at all by either using containers of sufficient wall thickness or flushing with inert gas before sealing.  Heavy wall thickness is one reason why the six gallon Super Pails have become so widespread.  It should be noted that Mylar is not strongly resistant to insect penetration and not resistant at all to rodents.  If mice chew through your buckets, they’ll go right through the bags.

HOW DO I USE  MYLAR BAGS?

Sealing food in Mylar bags is a straight-forward affair, but it may take a bit of practice to get it right, so purchase one or two more bags than you think you’ll need in case you don’t immediately get the hang of it.

#1 – The bags typically sold by storage food dealers look rather large when you compare them to the five or six gallons buckets they are commonly used in.  That extra material is necessary though if you are to have enough bag material left over after filling to be able to work with.  Unless you are sure of what you are doing, don’t trim off any material until after the sealing operation is completed.

#2 – Place the bag inside the outer container and fill with the food product.  Resist filling it all the way to the top.  You need at least an inch or so below the bucket rim left open to get the lid to seat completely.  If you’ll be using desiccants and oxygen absorbers together place the desiccant on the bottom of the bag before filling.

#3 – When the pail seems to be full, gently thump it on the floor a few times to pack the product and reduce air pockets.  Add any makeup food necessary to bring level back to where it should be.

#4 – Take the bag by the corners and pull out any slack in the material so that all sides can be pulled together evenly.  Place your oxygen absorbers inside if you are going to use them.  Now place a board over the top of the bucket and fold the bag end down over it keeping it straight and even.  Place a piece of thin cotton fabric such as sheet or t-shirt material over the edge of the bag mouth.  Using a clothes iron set on the cotton, wool or high setting run it over the cloth-covered Mylar about a half-inch from the edge for about twenty seconds or so until it seals.  You’ll probably have to do the bag in sections.  Temperature settings on irons vary so experimenting on a left-over strip to find the right setting is a good idea.

#5 – When you’ve done the entire bag allow it to cool then try to pull the mouth of the bag open.  If moderate pressure doesn’t open it, fold the bag down into the pail until you feel the trapped air pillowing up against the material and wait to see if it deflates.  If it stays buoyant, your seal is good.  You can seal on the bucket lid at this point or take the further step to vacuum or gas flush the bag.

Once a seal has been obtained the bags can be left as-is, vacuum sealed or gas flushed.  To obtain the most efficient oxygen removal the bags can be first drawn down with a vacuum pump and then purged using an inert gas.

Vacuum Sealing Mylar Bags

Once you have obtained a good seal on the bag, pulling a vacuum on the contents is straight forward.

First you’ll need something to make a vacuum with.  This can be either a regular vacuum pump, a vacuum sealer such as the Tilia Food Saver or even the suction end of your household vacuum cleaner.  The end to be inserted into the bag will need to be of fairly small diameter in order to keep the hole in the Mylar from being any larger than necessary.   This means that if you use a vacuum cleaner you’ll need to fashion some form of reduction fitting.  One such that I’ve seen is a plastic film canister with a hole drilled in the bottom and a piece of plastic tubing epoxied in place.

Cut a hole into the Mylar bag on a corner, making the opening only just large enough to admit the vacuum probe.  Insert the nozzle and using a sponge, or something similar, push down on the material over the probe to make a seal.  Now draw down a vacuum on the bag.  When it’s drawn down as much as possible, run a hot iron diagonally across the cut corner resealing the bag.

Gas Flushing Mylar Bags

Flushing with inert gas works essentially like vacuum sealing except that you’re putting more gas into the bag rather than taking it out.  You’ll want to keep the entry hole small, but don’t make a seal around it as above.  Beyond that, follow the directions as given in Section III.B.2 – CO2 and Nitrogen.  When you feel that the bag has been sufficiently flushed, run the iron across the corner as above to seal.

Flushing with dry ice can also be done, but it is important to wait until the frozen carbon dioxide has completely sublimated into gas before making the final seal otherwise the bag will burst like an overfilled balloon.

REUSING OR RECYCLING PACKAGING

In an effort to save money or because new packaging may be hard to come by, it is common for many people to want to re-use previously used containers.  There is nothing wrong with this, but it is sometimes more complicated than using new containers would be.  Here are some general rules if you have an interest in doing this.

#1. Do not use containers that have previously contained products other than food.  There are two risks this can expose you to.  The first is that the particular package type may not have been tested for food use and may allow the transfer of chemicals from the packaging into your food.  The second is that all plastics are porous to some degree.  Small amounts of the previous contents may have been absorbed by the packaging material only to be released into your food, particularly if it is wet, oily or alcoholic.

#2. Previously used containers should only be used with foods of a similar nature and exposed to similar processes.  This means that if a container previously held a material high in fat, such as cooking oil, then it should not be used to store a strong acid such as vinegar.  Nor should a container be exposed to extreme conditions, such as heat, if the original use of the package did not subject it to that treatment.  An exception to this is glass which is covered below.  Generally speaking, dry, non-oily, non-acidic or alkaline, non-alcoholic foods may be safely contained in any food safe container.  An example of this is keeping grains and legumes in HDPE buckets formerly containing pickles.

#3. Glass may be used to store any food provided it is in sound condition and has only been used to store food previously.  The lid or cap, however, that seals the jar is subject to the cautions given above.  Glass jars not specifically made for home canning, either boiling water bath or pressure canning, have a significant risk of breakage if used for that purpose.

#4.  Porous packaging materials such as paper, cardboard and Styrofoam should not be reused.  Their open texture can trap food particles and are difficult to adequately clean. Packaging formerly holding raw meats, seafoods, or egg products are particularly at risk.

#5.  Containers previously holding odorous foods may trap those odors and transfer them to foods later stored.  Pickle flavored milk leaves a lot to be desired.   Foods such as dry milk powders, fats and oils, flours and meals will absorb any odors seeping from your container material. Be sure to get the smell out before you fill them.