# How long will canned foods last?



## Moby76065 (Jul 31, 2012)

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.

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.

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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## JayJay (Nov 23, 2010)

About 110 cases of botulism occur in the U.S. per year. Most of the cases are in infants

However, of the approximate 140 cases per year in the U.S., there are usually only 1-3 deaths.

A high percentage of botulism cases (approximately 25 per year) in the U.S. are reported in Alaska, usually from the eating of contaminated marine mammals, ...

Each year in Washington state there are 0 to 4 reports of foodborne botulism, 0 to 9 reports of infant botulism and 0 to 7 reports of wound botulism

~~~and this is just the first page scanning the search~~~

I'm not worried about the 1992 home canned green beans I just ate.


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## Caribou (Aug 18, 2012)

My twenty year old salmon sure tasted good.


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## faithmarie (Oct 18, 2008)

Caribou said:


> My twenty year old salmon sure tasted good.


How long ago did you eat it? LOL

Is there a way to protect canned food in a cabin through the winter when there is no heat? Usually the canned food the next year that were left there, loose their flavor and the glass ones are discolored and not from light .... when they don't break.


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## JayJay (Nov 23, 2010)

Caribou said:


> My twenty year old salmon sure tasted good.


Are we rebels or what??:ignore:


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## mojo4 (Feb 19, 2012)

If I end up eating canned food long after the expiration date I plan on cooking the hell out of it. If botulism is there it will die at 150 degrees for an hour or so.


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## 101airborne (Jan 29, 2010)

Depending on the food your talking about. I've eaten canned spam that was 20 years old and just fine. Same with military C rations back in the 80's we ate korean war era rations that were fine. I think the biggest issue would be damaged cans and bad seals. If the can is stored properly and undamaged I'd guess that it would be okay for decades. My main concern would be the loss of nutritional value.


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## Moby76065 (Jul 31, 2012)

mojo4 said:


> If I end up eating canned food long after the expiration date I plan on cooking the hell out of it. If botulism is there it will die at 150 degrees for an hour or so.


My understanding Mojo is that all canned foods should be boiled for 10 minuets and everything is killed. BUT....you open a jar of canned food and ensure the vaccum seal was good, it smells right, etc. THEN still boil it for ten minuets.

I've never had an issue.


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## mojo4 (Feb 19, 2012)

Yep. Cook it till it stops squirming!!


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## DJgang (Apr 10, 2011)

I was thinking.... What if you dehydrated it before expiration, I mean store bought???


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## slowimplosion (Sep 9, 2012)

I'm referring to store-bought canned (tinned) foods, not the home canned variety.

I started storing food in 2005. Since then, I have eaten plenty of stuff that was 5+ years old. I give it no special preparation. I've had no issues.

That said, I have had about 1% of my cans go bad, all of them canned fruit. These cans always fail the same way, they swell up until they split a seam and leak.

Now, if you are going to eat something out of a can that is old, you will want to take extra precautions. Careful visual and olfactory examination is in order. But overall, canned food storage done right is excellent.


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## tsrwivey (Dec 31, 2010)

I just don't think I'm going to feed my family anything over 5 years old. If we haven't wanted to eat it in 5 years, it wasn't a good choice for us to store it or even buy in the first place. :dunno:


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## Davarm (Oct 22, 2011)

Caribou said:


> My twenty year old salmon sure tasted good.


When going through my late grandmothers utility room, I found a few jars of "Tomatoes and Okra" that were canned in "79" and I decided to try them.

They smelled just like fresh but the texture was not that good. After the first few spoons I decided that the experiment was over, I am still alive and If I was hungry enough I would have finished the jar.

Almost 35 years old.......


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## BillM (Dec 29, 2010)

Your canned goods will last until you eat them all !


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## db2469 (Jun 11, 2012)

BillM said:


> Your canned goods will last until you eat them all !


So, if commercially canned foods will last for 5-10 years or more, why are the expiration dates on the cans only for a few years in most cases?


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## BillS (May 30, 2011)

db2469 said:


> So, if commercially canned foods will last for 5-10 years or more, why are the expiration dates on the cans only for a few years in most cases?


It's done partly to exempt the companies from liabilities from old food. I once worked at a place that canned food and had a lab. Food at 100º aged 3 times faster than food at 72º. That should reinforce the idea of keeping your cans as cool as possible but above freezing.

I found this too:

"Canned products may be stored for at least two years from the date of processing. Theoretically, canned food has an almost indefinite shelf life at moderate temperatures (75° Fahrenheit and below). Even if the can is 100 years old, is intact, and is not leaking, its contents should be edible. Although most experts agree that canned food preserves its safety beyond two years, it may have some deviation in quality, e.g. change of colour or texture.

With this regard, presently, many canned products have a "for best quality use by" date stamped on the can; "expiry" date is less often found on canned food."
Source(s):
http://www.frosha.com/canned-food-facts.html


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## dixiemama (Nov 28, 2012)

I've been slowly weaning us from commercial canned foods due to chemicals used in dealing cans and preserving food. It's helped that we have a garden to grow the few veggies we actually like.


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## webeable (Aug 29, 2012)

Just saying that Cambells test their products are still good at 20 years on soup.


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## cowboyhermit (Nov 10, 2012)

The reason they don't put longer expiry dates on cans is because it just isn't worth it. They pick an ultra conservative number and if people throw away cans at home what do the companies care, they got paid.

slowimplosion, I would be very concerned with a 1% failure rate, I have seen more like 0.01%

Boiling will kill off any botulism toxin that has formed but if the cans are not deformed it should not exist. We do not boil all our canned foods.

Proteins, carbs, fats, and minerals will all be there in properly canned foods, even after years. I don't really count on vitamins in canned food, even if done recently, but after years vitamin levels WILL be diminished.


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## JayJay (Nov 23, 2010)

slowimplosion said:


> I'm referring to store-bought canned (tinned) foods, not the home canned variety.
> 
> I started storing food in 2005. Since then, I have eaten plenty of stuff that was 5+ years old. I give it no special preparation. I've had no issues.
> 
> ...


Like you, I already have canned goods over 4 years old. Many,many,mnay!!
I'm curious, what fruits were bad??
I have applesauce, pears, peaches, mandarin oranges, pineapple.


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