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Revised Dec. 21, 2009 Also, read about our experience with seed
sprouts (bottom of that page)
We know you're busy and don't have time to sink your teeth into an internet article, so here's the short version for length-of-life for canned foods:
In 1820, William Perry (Parry) took an expedition in search of the Northwest Passage, toward the North Pole. He took with him some canned meats. At the time, food canning was about a 10-year-old technology.
At least one can of meat was not used and wound up in a museum in England. In 1938, it was opened and found to be edible. It was fed to a cat which suffered no ill effects from eating the 118-year-old meat.
Now, we're not saying that our canned meats, canned cheese and canned butter will last 118 years, but we're pretty confident that you can get at least a 15-20 year shelf life out of them, in light of this article. (The manufacturer offers a 3 year guarantee.) There's a second, similar story--this time American--following this one.
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Below, we're reprinting the article (in case the link to it stops working). I hope you'll kick your shoes off and take a minute to read it. . . .
The article itself can be found here (1-17-07).
THE GREAT INTERNATIONAL SEARCH FOR NEW TERRITORY further propelled
the use and notoriety of the can. Likewise, the advantages of well
preserved canned food enabled bolder expeditions. Explorers in search
of the elusive Northwest Passage, such as Otto von Kotzebue of Russia,
were quick to benefit. He wrote of a "discovery made lately in England"
which he thought "too important not to be made use of," and took some
canned meats with him on his voyage in 1815.

 Honest Spices Nutmegs, probably c. 1890; Nestle's Milk Food, probably c. 1890; Windsor Coffee; Borden's Evaporated Milk; Royal Baking
Powder, c. 1940; Sauer's Cloves.
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Sir William Edward Parry made two arctic expeditions to the
Northwest Passage in the 1820's and took canned provisions on his
journeys. One four-pound tin of roasted veal, carried on both trips but
never opened, was kept as an artifact of the expedition in a museum
until it was opened in 1938. The contents, then over one hundred years
old, were chemically analyzed and found to have kept most of their
nutrients and to be in fairly perfect condition. The veal was fed to a
cat, who had no complaints whatsoever.
Swain, Earle and Co. tea.

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As
cans traveled over land and sea, can making spread as well. In Germany,
where tinplate had been invented hundreds of years earlier, tin cans
were made by hand by plumbers—artisans who, in those days, worked
primarily with lead, zinc, tin and other metals.
The father of the can manufacturing industry in the United States
was an Englishman who immigrated to the new country and brought his
newfound canning experience with him. Thomas Kensett set up a small
canning plant on the New York waterfront in 1812 and began producing
America's first hermetically sealed salmon, lobsters, oysters, meats,
fruits and vegetables. Kensett began his operation using glass jars
but, finding glass expensive, difficult to pack and easily broken, soon
switched to tin. He and his father-in-law, Ezra Daggett, were awarded
the U. S. patent for preserving food in "vessels of tin" by President
James Monroe in 1825.
A competitor, Charles Underwood, set up shop in Boston and preserved
fruits, pickles, and condiments in crocks. Underwood was also an
Englishman and had landed in New Orleans originally, but found no one
there interested in his canning idea. After making his way to Boston on
foot, he started his business which shipped its products primarily to
South America and the Far East. He too eventually switched to tin.

 Female cannery workers in an oyster-packing factory fill hole-and-cap cans, c. 1872. The sanitary can would replace the hole-and-cap design by the early 1920s.
Canned Food Safety: The Canning Process by Food and Drug Administration (FDA)
From http://www.enotalone.com/article/7794.html
The steamboat Bertrand was heavily laden with provisions when it set out on
the Missouri River in 1865, destined for the gold mining camps in Fort Benton,
Mont. The boat snagged and swamped under the weight, sinking to the bottom of
the river. It was found a century later, under 30 feet of silt a little north of
Omaha, Neb.
Among the canned food items retrieved from the Bertrand in 1968 were brandied
peaches, oysters, plum tomatoes, honey, and mixed vegetables. In 1974, chemists
at the National Food Processors Association (NFPA) analyzed the products for
bacterial contamination and nutrient value. Although the food had lost its fresh
smell and appearance, the NFPA chemists detected no microbial growth and determined that the foods were as safe to eat
as they had been when canned more than 100 years earlier.
The nutrient values varied depending upon the product and nutrient. NFPA
chemists Janet Dudek and Edgar Elkins report that significant amounts of
vitamins C and A were lost. But protein levels remained high, and all calcium
values "were comparable to today's products."
NFPA chemists also analyzed a 40-year-old can of corn found in the basement
of a home in California. Again, the canning process had kept the corn safe from
contaminants and from much nutrient loss. In addition, Dudek says, the kernels
looked and smelled like recently canned corn.
The canning process is a product of the Napoleonic wars. Malnutrition was
rampant among the 18th century French armed forces. As Napoleon prepared for his
Russian campaign, he searched for a new and better means of preserving food for
his troops and offered a prize of 12,000 francs to anyone who could find one.
Nicolas Appert, a Parisian candy maker, was awarded the prize in 1809.
Although the causes of food spoilage were unknown at the time, Appert was an
astute experimenter and observer. For instance, after noting that storing wine
in airtight bottles kept it from spoiling, he filled widemouth glass bottles
with food, carefully corked them, and heated them in boiling water.
The durable tin can — and the use of pottery and other metals — followed
shortly afterwards, a notion of Englishman Peter Durand. Soon, these "tinned"
foods were used to feed the British army and navy.
21 Billion Cans a Year
Canned foods are more than a relic dug from the past. They make up 12 percent
of grocery sales in the United States. More than 1,500 food products are canned
— including many that aren't available fresh in most areas, such as elderberry,
guava, mango, and about 75 different juice drinks. Consumers can buy at least
130 different canned vegetable products — from artichokes and asparagus to
turnips and zucchini. More than a dozen kinds of beef are canned, including beef
burgers and chopped, corned and barbecued beef.
According to a recent study cosponsored by the U.S. Department of Agriculture
and NFPA, canned foods provide the same nutritional value as fresh grocery
produce and their frozen counterparts when prepared for the table. NFPA
researchers compared six vegetables in three forms: home-cooked fresh, warmed
canned, and prepared frozen.
"Levels of 13 minerals, eight vitamins, and fiber in the foods were similar,"
says Dudek. In fact, in some cases the canned product contained high levels of
some vitamins that in fresh produce are destroyed by light or exposure to air.
The Canning Process
Food-spoiling bacteria, yeasts and molds are naturally present in foods. To
grow, these microorganisms need moisture, a low-acid environment (acid prevents
bacterial growth), nutrients, and an appropriate (usually room) temperature.
Dennis Dignan, Ph.D., chief of FDA's food processing section, explains that
foods are preserved from food spoilage by controlling one or more of the above
factors. For instance, frozen foods are stored at temperatures too low for
microorganisms (bacteria, yeasts and molds) to grow. When foods are dried,
sufficient moisture is not available to promote growth.
It is the preservation process that distinguishes canned from other packaged
foods. During canning, the food is placed in an airtight (hermetically sealed)
container and heated to destroy microorganisms. The hermetic seal is essential
to ensure that microorganisms do not contaminate the product after it is
sterilized through heating, says Dignan. Properly canned foods can be stored
unrefrigerated indefinitely without fear of their spoiling or becoming toxic.
Canning for a New Age
Dignan also notes that foods packaged in materials other than metal cans are
considered "canned" by food processing specialists if the food undergoes the
canning preservation process. Thus, today a canned food may be packaged in a
number of other types of containers, such as glass jars, paperboard cans, and
plastics that can be formed into anything from pouches to soup bowls to serving
trays.
For example, FDA consumer safety officer Tom Gardine, holding up a small,
plastic container of half-and-half for his morning coffee, says, "This is a
canned food." He explains that the coffee creamer was heated to destroy bacteria
and sealed to prevent microorganisms from entering the sterile container. Until
it is opened, the creamer is intended to be stored on the shelf, not in the
refrigerator.
Meals for today's U.S. military come in plastic pouches — a new version of
the heavier C-rations in metal cans. Such flexible pouches aren't as popular
with American civilians as they are with Europeans. Many Americans, instead, are
buying their canned foods in plastic containers that come with a peel-off metal
top and plastic lid — ready for the microwave. Barriers (made of sophisticated
synthetic materials) that provide an airtight seal are sandwiched in these
plastic layered containers. They are used for applesauce, pudding, and other
foods that can be stored on supermarket or home shelves for years.
Then there are containers made of new transparent plastic materials like
polyethylene terephthalate — used for peanut butter and catsup. Packages made of
paperboard layers have been designed in the shape of boxes to contain such foods
as fruit juices, tomato sauce, and even milk.
Even the tin can is changing. For years, the three-piece can (made from a
top, a bottom, and a body formed from a plate soldered into a cylinder) was the
only can around. Now there are two-piece cans, which eliminate the side seam and
one seamed end. These cans are made by feeding metal into a press that forms the
can body and one end into a single piece.
In the traditional three-piece cans, a welded side seam has replaced the
lead-soldered side seam in all but 3.7 percent of American cans, says NFPA
official Roger Coleman. The welding process uses electrodes that apply pressure
and electric current to overlapping edges at the side seam. These new seams
eliminate concern about lead leaching into metal canned foods. In the 3.7
percent of U.S. cans where lead still is used, it is often for dry foods (such
as coffee) packaged in cans, according to Coleman. Leaching is not a concern
here.
Many imported cans, however, still bear lead-soldered side seams. To tell
whether a can has been soldered with lead, first peel back the label to expose
the seam. The edges along the joint of a lead-soldered seam will be folded over.
Silver-gray metal will be smeared on the outside of the seam. A welded seam is
flat, with a thin, dark, sharply defined line along the joint.
Turning Up the Heat
Foods with a naturally high acid content — such as tomatoes, citrus juices,
pears, and other fruits — will not support the growth of food poisoning
bacteria. In tests, when large numbers of food poisoning bacteria are added to
these foods, the bacteria die within a day. (The exact amount of time depends
upon the bacteria and amount of acidity.) Foods that have a high acid content,
therefore, do not receive as extreme a heat treatment as low-acid foods. They
are heated sufficiently to destroy bacteria, yeasts and molds that could cause
food to spoil.
Canners and food safety regulators are most concerned about foods with low
acid content, such as mushrooms, green beans, corn, and meats. The deadly
Clostridium botulinum bacterium, which causes botulism poisoning, produces a
toxin in these foods that is highly heat-resistant. The sterilization process
that destroys this bacteria also kills other bacteria that may poison or spoil
food.
Low-acid canned foods receive a high dose of heat — usually 107 degrees
Celsius (250 degrees Farenheit) for at least three minutes. (The amount of time
the food is heated, though, depends upon the size of the container and the
product.) The canned food is heated in a retort, a kind of pressure cooker.
The coffee creamer on Gardine's desk, however, was packaged differently.
Although both the half-and-half and plastic container were sterilized with heat,
they were heated separately and then brought together in a sterile environment
where the container was filled and sealed. The advantage of this "aseptic
processing," a type of canning, is that higher temperatures with reduced heating
times prevent deterioration in the quality of the food.
Aseptic processing is the "wave of the present and the future," says Gardine.
It is now used for liquids, and scientists are on the way to perfecting the
method for canning stews and chowders. However, says Gardine, because solid
foods may be more difficult to keep sterile during the filling and sealing
period, FDA is being especially cautious in approving uses for aseptic
processing.
Finessing the Attack on Food
Spoilers
Another critical element in the canned food process is sealing products in
air-tight containers. It is essential that air be removed from the container
before sealing. Air could cause the can to expand during heating, perhaps
damaging the seals or seams of the container.
A telltale sign of loss of this vacuum — and a possibly contaminated product
— is a can with bulging ends. (See accompanying article.) If a seal is not
airtight, bacteria may enter the can, multiply, and contaminate the product.
The hermetic seal finesses the canning process. The bacteria in a food and
container are killed through heating, and at the same time new bacteria are kept
from contaminating the food.
The distinction between the canning process and food handling before
processing is an important one for food processors and regulators. Last
February, 22 students at Mississippi State University became ill after eating
omelets made with canned mushrooms imported from China. Similar outbreaks
followed in New York and Pennsylvania, affecting more than 100 people. FDA
identified the culprit as staphylococcal enterotoxin, a poison produced by the
bacteria Staphylococcus aureus.
FDA's investigation suggests that poor sanitation caused the problem, and
that the mushrooms were contaminated with staphylococcal enterotoxin even before
they were canned. The canning process did not destroy the substance because food
preservation processes are not normally designed to destroy staphylococcal
enterotoxin, a highly heat-resistant toxin.
Since this incident, FDA and the Peoples Republic of China have been working
together to determine the source of the contamination. However, FDA authorities
still are preventing mushrooms canned in China from entering the United States.
And, says Gardine, FDA is focusing attention on sanitation procedures in
imported foods.
Surpassing Napoleon
The canned food principle that won Nicolas Appert his prize of 12,000 francs
has endured over the years. What might surprise Appert, however, is how his
discovery is making food shopping and storing easier for the 20th century
consumer.
Those who order coffee at fast food restaurants now also are served canned
half-and-half, which has been transported and stored without concern about
refrigeration. Hikers can take flexible pouches of canned food on backpacking
trips without having to worry about saving water to reconstitute freeze-dried
meals. And, in this society of microwave owners, Americans who don't have time
to prepare a well-balanced meal can pick up a plastic container filled with a
canned, nutritious dinner.
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