Freeze Dried and Dehydrated Food Shelf Life
There are many factors that can affect the storable life of your freeze dried and dehydrated bulk food. Please take the time to read this information page if you are not aware of how foods are packed and how they should be stored.
Dehydration and freeze dried techniques have come a long way in recent years. Old technology left as much as 30% moisture in the dehydrated products. These poorly dehydrated foods didn't store very well. Recent advancements in technology have made significant improvements, with moisture levels now at 2% or 3%. Gone are the pliable dehydrated foods. Now they break with a crisp "snap" when bent. With moisture levels reduced to 2% - 3%, storage life has been increased dramatically.
It is important to keep in mind that not only do colder temperatures affect shelf life
of food products, temperature fluctuations affect shelf life too. Keeping your food
stored at a constant temperature will help you acheive the maximum shelf life. As
you can see from the below chart, it is not that hard to obtain 10+ years on your food
storage. Finding a cool, dry location, such as a basement or root cellar is perhaps
your best insurance on maximizing the shelf life on your stored foods.
|Storage Life & Temperature
|Temperature and temperature changes have the most to do
with the shelf life of stored food than any other factor. The USDA states: "Each
5.6 C. (10.08 F) drop in temperature doubles the storage life of the seeds." Experience
has shown that this applies to foods too.
(See also the
product chart below )
Foods that will be prepared and consumed rapidly don't need any special storage
requirements. Such foods can be stored at room temperatures with no appreciatable
loss of quality or nutrition. The above chart demonstrates that bulk food can be
stored in warm areas for several years.
Many products, such as dry beans, grains, and flours contain an average amount of 10%
moisture. Although it is not necessary (and very difficult) to remove all moisture from
dry food, it is important that any food stored be stored as dry as possible. Excess
moisture can ruin your food stored.
Oxygen can be removed from the food storage container, resulting in the food lasting
much longer than normal. Oxygen, naturally found in air will oxidize many food
compounds. There are a couple of techniques used to remove oxygen from food containers:
- Displacing the oxygen with nitrogen: Air is purged out by inserting a nitrogen
wand into the food container. Nitrogen is the most inert gas known.
- Absorb the oxygen: The oxygen absorber packet absorbs the oxygen. Air contains
about 78% nitrogen and 21% oxygen, leaving about 1% for the other gasses. The oxygen is
absorbed, leaving about 99% pure nitrogen in a partial vacuum. Our food products in cans or
buckets all come with oxygen absorbers in their containers.
- Dry Ice: Home storage can be accomplished by using dry ice (carbon dioxide) obtained from a local source. The dry ice is place in the container (usually a bucket) and allowed to evaporate, displacing the oxygen. It's no longer commonly used when oxygen absorbers are so readily available and cheaper, but it will work.
- Must Read: Wise Foods Laboratory Analysis - A shocking revelation reveals extremely high oxygen levels. Mountain House has had Wise Foods tested through a 3rd party laboratory in order to investigate Wise Foods' shelf life claims. Tests revealed the presence of extremely high oxygen levels in Wise Foods. Due to these findings, shelf life claims for these products are wildly inaccurate.
An air tight seal on the food storage container is a must. All of our food is
packed in air tight, sealable food grade cans or buckets with gasket lids (except for items ordered in bags or boxes)
with an appropriately sized oxygen absorber.
Some foods are available in Mylar pouches which are airtight if left unopened. Maximum shelf life is achieved best with either cans or buckets. Boxed or bagged items can be consumed immediately or repackaged into food grade airtight containers. We recommend buckets with gasket lids and / or heavy Mylar bags with oxygen absorbers for boxed or bagged products.
To ensure maximum shelf life, store your food storage in a cool, dark location out of direct sunlight. Avoid direct contact with concrete floors by elevating your cans or buckets off the floor with pallets or wood boards. High humidity evironments will affect opened containers, but will have no affect on factory sealed air-tight containers.
Barometric pressure can dent or - in the case of severe barometric pressure changes (altitude, hurricanes, etc.) - severely dent buckets. This is usually a "good sign", since it indicates a tight seal on the gasket lid. Generally bucket dents only occur with people who live at very low elevations near sea level. The lower in elevation you are, the more atmospheric pressure there is, consequently the buckets can dent. If these are SP buckets (the food is in a sealed mylar bag inside) and you want to remove the dents, you can crack the lid open and allow in some air, but this is not always necessary or generally recommended.
Dents can be ignored unless they are problematic and threaten the integrity of the bucket. In the case of severe dents the lids can be removed on SP buckets (products with mylar bags) and the sides pushed out and the lid replaced. Do not do this on RB (ribbed) buckets as they do not have a mylar bag inside (unless you replace the oxygen absorber after pushing out the dent). We always recommend the SP buckets over the RB buckets since the mylar bag provides an extra layer of protection. Customers are responsible for making periodic inspections of their food storage and ensuring proper storage conditions.
Average Shelf Life of Dehydrated Products
Below is a chart to help you determine the shelf life of food stored in air tight
containers at an optimum temperature of 60 degrees (cooler, colder temperatures are best). All of the following
products will store proportionally longer at cooler temperatures if kept
at lower storage temperatures. Higher storage temperatures will decrease shelf life. Shelf life of 30+ years is perfectly feasible for many products with proper storage conditions and temperatures!
* Products that contain yeast (leaven) should be considered as having a shorter shelf life than products that do not contain this ingredient. There are active enzymes in leaven, which create carbon dioxide gas, the same gas used in food storage (dry ice method). The gas is harmless to food. Leaven by itself has a 2 year shelf life (see Yeast above).
Shelf life beyond these figures decrease in nutritional quality and taste. All foods should be checked prior to consumption for staleness, bad odor, or obvious signs of deterioration. The above table represents average shelf life for these products at 70 degrees and is not a guarantee.
Average Shelf Life of Freeze Dried Products
Freeze drying is the most effective way to remove water from food. Freeze-drying (also known as lyophilization or cryodesiccation) is a dehydration process typically used to preserve food and make it more convenient for transport and storage.
Freeze-drying works by freezing the food and then reducing the surrounding pressure and adding just enough heat to allow the frozen water in the food to sublime directly from the solid phase to the gas phase.
If freeze-dried food is then sealed to prevent the reabsorption of moisture, the food may be stored at room temperature without refrigeration, and be protected against spoilage for many years. Preservation is possible because the greatly reduced water content inhibits the action of microorganisms and enzymes that would normally spoil or degrade the food.
Freeze-drying also causes less damage to the food than other dehydration methods that employ the use of higher temperatures. Freeze-drying does not usually cause shrinkage or toughening of the material being dried. In addition, flavors, smells and nutritional value generally remain unchanged, making the process popular for preserving food.
For optimal shelf life it is best to store the products in a cool, dry environment. We recommend 65º or less; the cooler the better. High heat that occurs in a garage or the trunk of a car is not good for freeze dried products.
Key advantages of freeze-dried products:
- 98% of the moisture is removed.
- Retains the original taste and nutritional value of the food.
- Foods are quick to reconstitute and easy to prepare.
- Hot or cold water may be used for reconstitution (although cold water takes longer).
- Extends the shelf life of the product.
- No preservatives are necessary.
- Results in a super-lightweight / compact product.
1. Mountain House freeze-dried foods are packed in airtight NITROGEN PACKED #10 cans. Up to 98% of the residual oxygen has been removed. Their unique canning process uses both vacuum oxygen removal and nitrogen flushing. This is a time consuming and slightly more costly process. It is the same process mandated by the U.S. Military for whom they also can.
Must Read: Mountain House drops bombshell press release on Wise Food (revealing information), and also, Mountain House products are exceeding 30 year shelf life. (We do not recommend Wise Foods!!!)
January 3, 2013 Notice:
We recently tested archived samples for nutrition, flavor, and texture, and found them to be virtually indistinguishable from new production, the very definition of “shelf life”.
As a result of our testing:
Effective immediately, the official shelf life of Mountain House pouches has been increased by over 40%, from 7 years to 10 years!
We also tested Mountain House pouches that were 30 years old. While there were recognizable differences in flavor and texture from new production (and therefore past their “shelf life”), the food was still delicious, wholesome, and nutritious!
In fact, our tasting panel found that 30-year old Mountain House food significantly outscored newly manufactured competitive products in a blind sensory evaluation.
We are confident that Mountain House provides consumers with the longest proven shelf life in the industry, as well as the longest proven storage time: our food remains not just barely edible, but delicious!
2. After 10 years, if stored properly, MH pouches can last many years, even decades beyond the 10 years.
3. Alpine Aire Gourmet Reserve cans and pouches have a very conservative estimate on shelf life. Properly stored, this can be expected to be much longer.
4. Mainstay Food Rations are not freeze dried products - they are specially formulated rations designed to survive temperature extremes that would destroy typical foods. These can be stored in a boat, car, camper, etc., where there are temperature fluxuations that would ruin MRE's (we do not recommend MRE's).
Predicting actual shelf life of dehydrated foods is not an exact science, however
there have been many studies done. In addition to the above average shelf life of
food stored at a constant 70 degrees, you can dramatically increase your life expectancy
by lowering the constant temperature. It is possible to double, triple or
even quadruple the shelf life by lowering the temperature proportionally.
Some products, such as seeds, can even be frozen for dramatically increased shelf
life. The basic rule of thumb is to store your food storage in as low of temperature
as possible to increase its shelf life and to retain nutritional value.
A new study by the Department of Nutrition, Dietetics and Food Science at Brigham Young University (*.pdf file) tested several varieties of dehydrated stored foods in #10 cans. They have learned that shelf life is considerably longer than previously thought. Here are their findings:
Nutritional Adequacy and Shelf Life of Food Storage by
Dean Eliason and Michelle Lloyd
Is my food storage still edible? How is the nutritional value?
In the Department of Nutrition, Dietetics and Food Science at
BYU, we have conducted research on long-term storage of food.
We have collected samples of dry food stored in No. 10 cans for
up to 30 years at room temperature or cooler. So far, we have
following food products: powdered milk, rice, baking powder, instant potatoes, dried apples, all-purpose flour, pasta, pinto beans, wheat and powdered eggs.
From this testing, we can generally conclude that if properly
packaged and stored, all of these foods store fairly well, except
for the powdered eggs. In general, the vitamins we have measured (thiamin, riboflavin, vitamin C, vitamin E) in properly stored foods are fairly stable over time.
If you think your food storage is getting too old, the best test would be for you to try a sample and decide if it is edible to you. Some people are more picky than others about the food they eat.
What is the nutritional value of basic food storage?
A year supply of basic food storage (400 lb wheat, 60 lb dry beans, 60 lb sugar, 16 lb powdered
milk, 10 qt oil, 8 lb salt) provides adequate calories but is lacking in calcium as well as vitamins A,
C, B12, and E.
Vitamins A and C can be found in canned or bottled
fruits and vegetables as well as in some fruit drink mixes.
Most vitamin C is destroyed during dehydration of fruits
and vegetables, but some vitamin A remains. Good
sources of vitamin A include canned pumpkin and
dehydrated carrots. Vitamin B12 comes from animal sources and can be found in canned meats and jerky.
Calcium comes mainly from dairy products such as
powdered milk, hot cocoa mix, and pudding mix
(containing dried milk). Vitamin E is found in fats and oils and can be found in nuts such as sunflower seeds and almonds.
Keeping Food For Years (Science Daily Article)
FOOD STORAGE - THE BASICS
Since the entire idea of a food storage program is that it should be available for you and yours in times of need, it is important to understand the conditions that can affect the edibles stored in your pantry.
A storage program is only as good as the quality of the food that goes into it. It cannot get any better than what originally went in, but it can certainly get worse. In the fullness of time, all stored foods will degrade in nutrients and palatability until they reach the inevitable end where even the dog won't eat them. It's because of this eventuality that every article, book, and teacher concerned with putting food by gives the same advice: Date all food containers and rotate, Rotate, ROTATE.
The first food in should be the first food out. This concept is often shortened to the acronym FIFO.
The reason for this emphasis on stock rotation is that when discussing the usefulness of foodstuffs there are really two shelf lives to be considered - the nutritional life and the palatability life. Nutritional content actually begins to fade at the moment of harvest with three major factors influencing nutrient retention: The food's initial nutrient content; the processing and preservation steps the food underwent; and the storage conditions in which it's kept. Given sufficient time, all but the most durable nutrients will dwindle away to nothing. Unfortunately, there is no good way outside of laboratory testing to know how much nutrition is left in a given food, but we can make our own determinations about other criteria which leads us to the palatability life mentioned also mentioned above.
A food's palatability life is the point at which undesirable changes occur to foods taste, texture, color and cooking qualities. This is the reason for the "use by" and "sell by" dates on many foods and for shelf lives in general. It will almost always be in excess of good nutritive life. If you don't have anything to replace old food with, it's not necessary to throw the food out just because it's reached the end of its best palatable storage life. Do, however, keep in mind that advancing age will only further decrease the useful nutrition, increase the foods' unattractiveness to being eaten and enlarge the chances that something may cause the food to spoil.
Within reason, the key to prolonging the shelf life of your edibles lies in lowering the temperature of the area they are stored in. The storage lives of most foods are cut in half by every increase of 18º F (10º Celsius). For example, if you've stored your food in a garage that has a temperature of 90º F, you should expect a shelf life less than half of what could be obtained at room temperature (70º F) this in turn is less than half the storage life that you could get if you kept them in your refrigerator at 40º F. Your storage area should be located where the temperature can be kept above freezing (32º F) and, if possible, below 72º F.
Ideally, your storage location should have a humidity level of 15% or less, but unless you live in the desert it's not terribly likely you'll be able to achieve this. Regardless, moisture is not good for your dry stored edibles so you want to minimize it as much as possible. This can be done by several methods. The first is to keep the area air-conditioned and/or dehumidified during the humid times of the year. The second is to use packaging impervious to moisture and then to deal with the moisture trapped inside. If you are able, there's no reason not to use both.
All containers should be kept off the floor and out of direct contact from exterior walls to reduce the chances of condensation brought on by temperature differences between the container and the surface it's resting against.
Another major threat to your food is oxygen. Chances are that if your foods are sealed in moisture-proof containers the containers are probably air-tight as well. This means that the oxygen can also be kept from doing its damage. If no more can get in, your only concern is the O2 that was trapped inside the container when it was sealed. Lowering the percentage of O2 to 2% or less of the atmosphere trapped inside the packaging (called head gas) can greatly contribute to extending its contents shelf life. The three main tactics for achieving this are vacuum sealing, flushing with inert gas or chemically absorbing the oxygen. Any one or a combination of the three can be used to good effect.
Once you have temperature, humidity and oxygen under control, it is then necessary to look at light. Light is a form of energy and when it shines on your stored foods long enough it transfers some of that energy to your food. This has the effect of degrading nutritional content and appearance. Fat soluble vitamins, such as A, D, E, and K are particularly sensitive to light degradation. It certainly is a pretty sight to look at rows and rows of jars full of delicious food, particularly if you were the one that put the food in those jars. However, if you want to keep them at their best, you'll admire them only when you turn the light on in the pantry to retrieve one. If you don't have a room that can be dedicated to this purpose then store the jars in the cardboard box they came in. This will protect them not only from light, but help to cushion them from shocks which might break a jar or cause it to lose its seal. For those of you in earthquake country, it's a particularly good idea. When "terra" is no longer "firma" your jars just might dance right off onto the floor.
Assuming they were properly processed in the first place, canned, dried and frozen (never thawed) foods do not become unsafe when stored longer than the recommended time, but their nutrient quality fades and their flavor, color and texture goes downhill. Following these rules of good storage will keep your food wholesome and nutritious for as long as possible:
- First In, First Out (FIFO) means rotating your storage
- Cooler is better
- Drier is better
- Less oxygen exposure means more shelf life.
- Don't shed light on your food.
Think of rotating your food storage as paying your food insurance premiums -- slacking off on rotation cuts back on your coverage. Is your food insurance up to date?