Debunking the Myth of Canned Food Expiration Dates, by T.L.

Canned Goods

Even if you’re not yet a prepper, you likely have at least some canned food goods on your shelf with an expiration date on them. Perhaps you have even taken up canning your own food. Either way, canned goods are a common staple. That is the case for good reason. However, do you really know the truth about canned food shelf life?

I’m surprised by how many people seem to have a deep trust of those “magical dates” on canned foods. But what are those dates anyway? What do they mean?

Myths to Debunk

Various Types of Canned Food Dates

Here, let’s debunk some of the myths that surround those dates on canned foods.

Commercial canned foods are generally “good” far beyond the dates stated. And, get this. In almost all cases, the dates stated on foods aren’t expiration dates anyway. Rather, they are “use by” dates.

The use-by dates on cans and packages serve to protect the reputation of the food. They have nothing to do with food safety, as the U.S. Department of Agriculture’s website clearly states:

“Use-by” dates refer to best quality and are not safety dates. Even if the date expires during home storage, a product should be safe, wholesome and of good quality if handled properly.

Actually, except for infant formula, product dating is not even required by federal regulations.

While they may not be required, generally you will see manufacturers use one of three types of dates on products. None of these is an expiration date. The dates used are:

  • A “Sell-By” date, which simply tells the store how long to display the product for sale.
  • A “Best if Used-By” date is what the manufacturer recommends for best flavor or quality. It is not a purchase or safety date.
  • A “Use-By” date is the last date recommended for the use of the product while at peak quality. The manufacturer of the product determines the date.

Of course, manufacturers have an incentive for consumers to purchase more food, so the temptation is there for them to recommend short-term dates to encourage more frequent purchases.

Long-Term Canned Goods Safety

Okay, you’re probably wondering how long canned foods remain safe. Am I right?

As it turns out, the answer is that canned foods are safe a lot longer than you think. Numerous studies show that foods are viable long after they were canned, or after the “expiration” of stamped dates.

For instance, a fascinating study published in the Journal of Food Science reported on canned food that was analyzed from the Steamboat Bertrand, which sank over 100 years before, in 1865. The findings? National Food Processors Association (NFPA) chemists detected no microbial growth. Furthermore, they determined that the foods were as safe to eat as when they had been canned over 100 years earlier.

The chemists added that while significant amounts of vitamins C and A were lost, protein levels remained high, and all calcium values “were comparable to today’s products.”

A prepper’s remedy for the loss of vitamins is, of course, to simply store and rotate multi-vitamins in his prepping supplies. That’s what I do.

Truthfully, these studies don’t surprise me. Proper canning creates a vacuum that prevents microorganisms and air from entering the jar. It is these that would otherwise contaminate the contents. As long as the seal is good, the contents should be good, which is why I’m comfortable eating a jar of stew from my pantry, even if I canned it 20 years before.

We have two All American pressure canners and use them to can all sorts of meats, stews, and vegetables. They are probably my most valued prepping item.

How To Determine Canned Food’s Safety

I pay no attention to those expiration dates. Instead, I look closely to ensure the seal hasn’t been compromised. Evidently authorities agree with this view. In a food safety fact sheet, Utah State University Food Safety Specialist, Brian Nummer wrote:

For emergency storage, canned foods in metal or jars will remain safe to consume as long as the seal has not been broken.

In yet another study, 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, the chemists said the kernels looked and smelled like recently canned corn.

Canned Goods Good for Preppers

So as these scientific analyses show, canned foods are an excellent option for preppers. If all that’s true, when would you ever discard a can of food? It’s unlikely that you’ll ever be forced with the decision of whether or not to open a can that is in fact 40 years old. However, if it has been several years and you come across a can that got lost in the pantry, it should be fine to eat if its seal hasn’t been compromised, just as the above studies attest.

Dented Cans

But what if the can is dented? Just as many people have tremendous belief in expiration dates, they also were led to believe that dented cans should be avoided or even discarded. It turns out that’s not usually the case.

The primary concern over dented cans is the very unlikely (but remotely possible) risk of botulism contamination.  We will take a closer look at botulism in a bit. So if people are leery of dents due to the risk of botulism contamination, when are dents to be considered a problem?

While very small dents almost always present no problem, the more important issue is the location of the dent. A can with a sharp dent on either the top or side seam should probably be discarded, because seam dents can allow the introduction of harmful bacteria. The good news is that most dents occur harmlessly on the side. Unattractive? Yes. But unsafe? No. Even the USDA agrees with this point when they say:

If a can containing food has a small dent, but is otherwise in good shape, the food should be safe to eat. Discard deeply dented cans. A deep dent is one that you can lay your finger into. Deep dents often have sharp points. A sharp dent on either the top or side seam can damage the seam and allow bacteria to enter the can. Discard any can with a deep dent on any seam.

What Is Botulism?

Botulism can be a deadly illness and is caused by various strains of the Clostridium bacterium.  The bacteria thrive in low-oxygen environments (such as those in canned food) and produce a neurotoxin that can cause loss of muscle control. If left untreated, the illness can spread throughout the body, ultimately reaching the respiratory system.

Clearly botulism is to be avoided at all costs.  But what are the odds that you can get botulism from canned food? I mean, do you know anyone who contracted botulism from commercially-canned food? Anyone?

How Common Is Botulism?

According to the CDC, an average of only 145 cases of botulism are reported in the U.S. each year. Of that, only 15 percent are the result of foodborne bacteria. Most botulism cases (65%) are infant botulisum, which is sometimes caused sometimes by feeding honey to infants. So, there are roughly 21 cases of foodborne botulism in the U.S. each year. Twenty-one out of over 300 million people, all of whom eat. As you can see, botulism is very, very rare. You should worry far more about dropping the canned food and breaking your toe.

Even in the very remote case of a bout with botulism, it certainly  doesn’t mean death. Botulism can be treated at a hospital with antitoxins. In fact, in the past 50 years, the fatality rate from botulism has dropped from 50% to 3-5%. So, out of 21 cases, a three percent fatality rate would mean that one American may die roughly every two years from foodborne botulism. And one person every two years is about what we find. Just this past week, a 37-year old man from California died, reportedly from eating nacho cheese contaminated with botulism.And two years ago a 54-year old person died in Ohio at an April 2015 church pot-luck dinner. The likely culprit in that botulism outbreak that sickened more than 20 was potato salad made from home canned potatoes. And therein lies the problem with most cases of botulism.

Home Canning

While there are, on average, 21 foodborne cases of botulism per year, many are the result of improper home canning. Now, I don’t know for certain how the potatoes in that instance were canned but most likely not with a pressure canner, such as the All American 921 Of course, botulism is something to be aware of, but there are many more threats in your life worthy of your attention, like…oh…not having any food stored at all..

Whether you can food yourself or buy from the store, all vegetables (including potatoes), all meats, etc. are low acid foods. Low acid foods must be canned in a pressure canner rather than a water bath canner.

However, many “old timers” canned those foods in water bath canners and got away with it. You may tell their children (most of whom are rapidly becoming old-timers themselves) that the foods must be pressure canned. And they will likely retort “Well, my mother always did it this way, so I will too.”

I use a pressure canner for pretty much everything other than jams and jellies. This means we’d be comfortable eating our cans of homemade chili 20 years from now.

Other Signs Canned Foods Arent Safe

Of course, botulism is something to be aware of, but there are many more threats in your life worthy of your attention, like…oh…not having any food stored at all.

Other signs that you should check to ensure your canned foods are safe include:

  1. Make sure the can is not bulging. This occurs when harmful bacteria, such as that which causes botulism, enters and creates gas.
  2. If the can has rust near the seams, inspect carefully. But rust or dents do not affect the contents of the can as long as the can does not leak. If the can is leaking, however, or if the ends are bulged, the food should not be used.
  3. Be very cautious if the can spurts liquid or foam when opened. This is not a good sign.
  4. Finally, trust your senses. If the food is discolored, moldy, or smells bad or simply doesn’t smell as it should (canned fruit that doesn’t smell fruity), then toss it. It’s not worth the risk.

What Have We Learned?

  1. There are no expiration dates, nor are they required. Rather, there are suggested dates by the manufacturer of when to use the food by. And the manufactures want you to think the food won’t last long, so you’ll buy more.
  2. Canning is a very safe process that protects the food for a long time–over 100 years, if necessary. That’s a fact.
  3. Botulism is a concern but rarely a legitimate threat. Just use your eyes and nose to assess the food. If the can is bulging (as in the picture above), by all means dispose of it. It’s definitely not worth the risk. But if it merely has a shallow dent and the seam hasn’t been compromised, it will likely pass the eyes and nose test.
  4. It’s best, in my view, if you can the food yourself, for the simple reason that you don’t have to worry about dents. Glass jars don’t dent. If the seal on the top of the jar is good, the food is good. Another reason it’s best to can your own food is that you don’t have to worry about your canning jars being lined with bisphenol A (BPA), as many canned foods are, just as water bottles are. The BPA has been linked to a rapid rise in blood pressure. And chronic exposure has been associated with heart disease. So get yourself a well-made pressure canner or borrow one from a friend. If you can’t grow food yourself, just buy some produce and meats from local farmers and start canning your own food. You won’t have to worry about BPA. You’ll know what’s in it, when it was canned, and you’ll learn a lifelong self-sufficiency skill.

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  1. Good article.

    Would remind readers that all food is organic based (not inorganic, but for trace minerals used by enzymes for a few biochemical reactions) and generally will not degrade unless exposed to a degradation (heat) environment or conversion through some enzymatic process (like digestion) or oxidation (exposure to oxygen) or in rare instances to light.

    Canning kills microorganism through a process where the DNA (and enzymes) is broken down by heat – the DNA and enzymes are an organic molecular structure but very susceptible to heat, radiation and enzymatic actions. Canning breaks these chemical bonds and prevents the microorganism from replicating and spoiling the food. Food preservation by irradiation is still used today and very effective but costly and safe. The organic material (carbohydrates and proteins) are far less susceptible to breakdown by heating but may degrade the quality of the food’s appearance and texture or tast) but the nutritional value will generally persist with only modest reductions over time; while fats are susceptible to oxidation, heat and breakdown from light and difficult to store.

    Up until the advent of canning – be it the tin cans or glass jars approach – most food storage was based on curing, smoking, dehydration or cooling – otherwise the food was consumed immediately. The advent of canning has been one of the events in history that has change the world dramatically – all places on the planet that have seen the advent of canned food have seen a dramatic increase in their standard of living (and our waistlines) but now threatens those that are so reliant on such food.

    As we all know, a disruption in our ever so fragile supply chain business models with a focus on just-in-time inventory managements is what makes our life so fragile.

    Having clean water, and a balanced long term supply of canned and dehydrated food is the only insurance policy to mange the risk of a food supply disruption (until the farm to market roads start to work again for those of us that know the history of our early roads system).

    Likely persuaded me to stock up on some more canned food, especially if you shop carefully (and store thoughtfully) and may also be time to look at the cost benefits of buying a $250 pressure canning equipment and the jars. Maybe a good bartering plan for those of us without a green thumb or big 2+ acre garden – I’ll can the food you grow if I get some for me.

    This article brought back memories from 35+ years ago in those food science classes in college – should have paid more attention and saved those books – since not much has really change in this science.

    As to Clostridium bacteria – in simple terms, what’s unique about this bacteria is that it is able to go into a phase of hibernation when environmental conditions would otherwise kill most bacteria – it creates a spore like structure that protects the DNA and crictical enzymes from heat and dehydration – the spore will allow the bacteria to come back to life and begin to replicate but if the bacteria is in a low oxygen environment it creates a by-product from the anaerobic metabolism that is a neurotoxin that is very heat tolerant and will not breakdown (similar to other food poisoning by stahloccocus bacteria) and therein is the problem. Spore formation can happen quickly in response to a quick change in the environment and still may be found in canned food – it’s only if the canned food then is kept in the right conditions after opening the food that may still be a problem from the neurotoxin or by infection in your gut (and the danger to young babies that don’t have a mature well developed gut flora to counter such an infection). The best indication of a bad canning situation is a bloated can – something is degrading and producing gas – never a good sign but not necessarily from clostridium bacteria. By the way, you can find this bacteria everyday in the soil nearly everywhere – it’s only if you but this bacteria in the right conditions that it creates the deadly poison that is heat tolerant and highly toxic. The other bacteria in this family also causes tetanus – step on a nail in your garden, and there’s a chance to get tetanus (lock jaw) from the neurotoxin from this bacteria that is a cousin of the one that causes botulism.

    Thanks for sharing and reminding us of the facts and opportunities – has prompted me to rethink the mix of types of food storage in the future., but not sure if I can convince my better half to start canning with me.

  2. What are your thoughts on oven “dry” canning of food with less than 10% moisture? I did this method and later found out it is not a safe procedure. Also, I noticed some moisture on a few of my jars on the sides and inside lid. I immediately released the seal now I’m concerned the food was comprised. Was that low-oxygen environment with moisture enough to produce the botulism bacteria? Been searching for answers as I it would be a lot of food I would have to discard. Thanks.

    1. I would toss the food. The food needs to be dried to very low moisture before being sealed in a jar. I use a vacuum sealer to seal dried food in jars. It works extremely well. The jar will do an excellent job of keeping moisture out, once sealed, just as it keeps moisture in with regular canning.

  3. I never tire of reading articles detailing basic information like this. I know that the Survivalblog readership is ever increasing. Repeating this kind of material provides new preppers with a window on reality not readily available in the usual day-to-day flow of information. It is nice to hear a little truth speak in the midst of all the spin.

  4. What are your thoughts on oven “dry” canning of food with less than 10% moisture? I did this method and later found out it is not a safe procedure. Also, I noticed some moisture on a few of my jars on the sides and inside lid. I immediately released the seal now I’m concerned the food was comprised. Was that low-oxygen environment with moisture enough to produce the botulism bacteria? Been searching for answers as it would be a lot of food I would have to discard. Thanks.

  5. Part of my food preps are store bought canned food. I keep them in the basement pantry using a rotation system first in first out. Its not uncommon to be using 2014 use by dated cans, we’ve never had a problem with any of them.

    Once we’ve used about 25% of any particular stack, say cream of chicken soup, it goes on my shopping list and I start looking around for the best sale price. Its a simple process and usually I’ll save 40% buying on sale over just buying singles off the shelf.

    The interesting trend is following the prices year over year, where for instance using the cream of chicken soup as an example the price has gone up 4x over the last 16 years, and if you don’t buy on sale, its closer to 7x.

  6. The only commercially canned food I have had storage issues with are tomato products and some fruit, peaches for example.They seem to eat through or expand the can. For this reason, I don’t stockpile those items anymore. I avoid foods canned in China as well. I just don’t trust the non-toxicity of their process.

  7. Just used a jar of home canned beef which I put up 11 years ago. It was overlooked in my rotation. I used it in a beef vegetable soup and it was as tasty as it was months after canning.I did note, however, that there were signs that enamel on the inner side of the lid was starting to show signs of corrosion. When this happens, the lid usually does not last for many more years.
    Of course it was pressure canned – we have been pressure canning for more than 50 years and I can count on the fingers of one hand the number of failures we have sustained Have to ad mit we do use the water bath for our pickles – they really turn to mush under pressure and we like the crunch we get with the lower temperatures. They are all used up in the following year so there is no problem.

  8. I’m starting to see rust on some of the cans in storage. I noted the lid on a Campbell’s tomato soup can with a best buy year of 2016. It had light rust and when I opened it found that the rust had penetrated to the side of the can under the seam. Our daily use can opener is one that cuts the metal on the side of the can just under the lid. I probably wouldn’t have noted the rust penetration if it was a top opened can. I guess my concerns here is the quality of the steel. I know a lot of steel is coming out of China and much of it is poor quality. I can’t help but wonder abut this effecting my storage.

  9. Canned foods from 40 years ago MAY be different than canned foods today. It’s the cans and how they are finished inside. I see what looks like laquer in some cans. Anyone care to comment?

    1. I have canned food in metal cans in my stash, but not a lot. There are many reasons.
      1. Metal rusts and corrodes, especially in this wet climate. It doesn’t matter what measures we take, it will rot down.
      2. As mentioned in the article, some foods that are high in acid help to rot the metal, no matter the inner lining.
      3. I want to be able to control the ingredients that are in those foods. I cannot eat most preservatives.
      4. I trust myself and my processes way more than I trust some tired, bored (even angry) factory worker who does this everyday for years on end.
      5. A glass jar with a metal lid is more likely to survive better than an entirely metal can. It is also easier to tell if it is unsealed.
      6. I can grow it myself with organic means, or nearly organic means.

      Hence, the reason I personally can most of our food instead of buying it.

  10. Expiration dates do not contribute to safety for the consumer. The dates encourage the waste of perfectly good food by encouraging people to throwing out usable food to increase sales.

    Starvation does not contribute to safety or security. It does contribute to avoidable suffering and death.

  11. Grow what you eat, eat what you grow – for those who do not grow, substitute the word “buy.” Point being that it is important in times of extreme stress to retain what normalcy you can. By ensuring that your diet is not a gross departure from what your normal, everyday diet consists of, you are raising the odds against a weakened immune system and gastrointestinal problems. Moreover, it ensures that you rotate your stock and become more proficient year over year in growing and thriving on what you produce and preserve.

  12. I switched to canning with plastic lids and no longer worry too much about corrosion. Tattler lids are a bit harder to get right in the process. But with practice, the fails go away. The nice thing is the lids are reusable, so all I have to replace are the rubber seals. The rings come off after the canning process prior to storage, and are kept dry in a drawer for later use.

  13. Mart
    May 28, 2017 at 2:08 pm

    The botulinum toxin is denatured and thus deactivated at temperatures greater than 80 °C (176 °F).

    Mart, are you referring to when the food is canned or when the can is opened and you cook/warm the contents (176 F)? It seems if heat would kill the bacteria, then wouldn’t one just heat to a safe temp and serve?

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