Posted by Eric Troy on 19 Jan 2015 22:21
You know when your milk is spoiled because you can smell it. In general, you know that if it is past its expiration date, it is not going to be good. You know that you can only keep meats or vegetables for a few days to a week (with some exceptions).
Yet, there are countless shelf stable foods in your pantry. Some of them sit there for years. Maybe you have a can of vegetables in your cabinet that has been there for years. On the bottom is an expiration date. It's expired! Does this mean it is unsafe to eat it?
Do canned foods really spoil that quickly? Is expired canned soup ok to eat? Should I throw it away if it is expired? If you want, you can skip to the short and sweet answer at the bottom. Read on if you want the full explanation.
The answer to the last questions is no, canned foods, including vegetables, soups, meats, etc., do not spoil that quickly at all. That is the whole idea behind canning, after all, to make the food shelf stable and able to be stored for long periods of time. Yet, the cans do bear a date on the bottom. This is confusing.
First, if you look through some of the cans in your pantry, you might notice that not all of them have dates. This is a clue. Obviously, dates are not mandatory. It is a choice of the manufacturer. You will tend to find dates on certain types of canned products. For example, canned soup will have expiration dates more often than canned veggies. Baby food and evaporated milk both have expiration dates. Some "dates" on the cans are codes which you will probably not be able to understand. These are called closed dates, as opposed to open dates which have recognizable months, days, and years.
For the most part, the dates, or codes, are there for the manufacturer so that they can keep up with the month, date, year, plant, and lot number of the can. What if they had to recall certain cans for whatever reason? These codes would help them identify which cans, and to inform consumers about whether their can is included in the recall.
Other times, the dates are for the purpose of helping grocery stores know when to rotate. They are not about when the food is unsafe to eat, but about the quality. Although a canned food stored for a long period may be quite safe to eat, it may have undergone some quality changes which effect its taste, color, etc. The manufacturer wants you to get the food in the best possible shape, since if you bought a can that was safe, but a little off, you might not buy their product ever again. So, the date is there, really, to protect the reputation of the product. It is a Best By or a Sell By date. Below is an example of a date on the bottom of a can. The date is not past on this particular image and is used as an example of such a date only.
Antique Canned Foods. Still good!
Some canned items will last a very long time without any recognizable change. For example, in this paper researchers describe the characteristics of some very old cans of food: a 40 year old can of corn, pickle relish found aboard the sunken U.S.S Monitor (sunk 1862), and several canned products from the steamboat, Bertrand (sunk 1865). The results prove that even foods canned using the earliest canning methods, like those pioneered by Bryan Donkin based on Nicholas Apperts processes (using glass) and Peter Durand's patent, can stand the test of time.
The 40 year old can of corn was from 1934, and had been found in a California basement. According to he researchers, the corn looked and smelled pretty much like ordinary corn.eat. It had actually held onto many of its nutrients, but lost some ascorbic acid (vitamin C). They got similar results from the other foods. In truth, nobody actually tasted the food, but chances are, they could have safety tried some.
This is not the only example of incredibly long-lived canned foods. In December, 1958, The British Food Manufacturing Industries Research Association analysed some "tinned" foods. These quite old cans had been family relics and were given to the association by private individuals for research purposes. These cans dated from the early 1800's when, unlike the average food can today, food was packed in cans which held over seven pounds of food. The oldest analyzed was a can of roast veal dating from 1823, manufacured by Donkin's company, which makes it basically as old as any canned food can be. The veal had quite a history, being a part of the 1824 Artic expedition of Captain Sir Edward Parry, on the HMS Fury. The family who donated it thought it to contain plum pudding, and had used it for many years as a door-stop!
Another donated can contained roast mutton, dated 1849, part of another long voyage, and expidition to search for the missing Captain Sir John Franklin, who was overdue from his trip to the artic to find a northwest passage, the same purpose of the expedition above.
The third container, from 1900, contained the plum pudding (or 'Christmas pudding) thought to be in the first can.
All the food had undergone various changes. There were trapped gases in the cans, either carbon dioxide or hydrogen, but neiter seemed to be due to mircoroganisms. The carbon dioxide, in the plum pudding, may have been due to the baking soda or some other leavening agen. The hydrogen found in the roast mutton and the plum pudding were thought to be the result of metal corrosion. The roast veal contained no gas, as it had a small leak.
The question of whether these early cans were sufficient to keep the food edible for such a long period is not the same question as whether the food was spoiled. The great amount of dissolved tin in the cans was deemed enough to make a person sick, for example. There was also, as would be expected, a large amount of iron, but also a large amount of lead. This metal, besides their potential danger (from the tin and lead, mostly), combined with the deteriorated fats and other changes to make the food taste very bitter. However, despite the very poor condition of the food, it was basically free of microorganisms, and, lacking anything else to eat, basically edible.
Your Nose Knows but Some Foods Last Longer Than Others
Usually, you should be able to go by your nose. If it smells funny, it is probably not going to taste good. However, I want to be clear on something: A bad smell doesn't automatically mean it will make you sick. Even expired milk or meat that is starting to smell funny won't necessarily make you sick (although the by-products of their metabolism might). The types of bacteria that produce illness don't usually produce a smell. What a bad smell does tell you for sure is that it will taste yucky and may (just may) make you sick.
Yesterday, I found a very old packet of pine nuts in my pantry. They were well past their date. I know that they were bound to have gone rancid, so I opened them and smelled them. They had the characteristic odor of rancid nut oil. I threw them out. If they had smelled fine, I would have used them.
Most canned foods will sit safely on your shelf for years and you will still be able to eat them, regardless of what the date says. But certain types of foods are more shelf-stable than others. Highly acidic foods will not hold up as long as less acidic foods. This means that a can of tomatoes, for example, will not last much past eighteen months while a can of green beans could last years (and years?). Other examples are pineapples and other high acid fruit, canned chili, sauerkraut, and the aforementioned soups, especially ones with an acid such as tomatoes.
You may assume that canned meat, poultry, and fish will not last as long as canned vegetables, but this assumption is not correct. They can last many years and you can eat a five year old can of SPAM or corned beef with not problems, as long as it has been stored in a cool, dry place.
Aseptically packaged milk (the shelf-stable kind in cartons) will not last indefinitely. You should go by the date on those. Try not to store canned and other packaged goods near a source of heat, such as an oven or stove, as this will effect their shelf-life and quality.
Product Dating Regulations
According to FDA regulations, product dating is not required except for infant formula and some baby food. These dates are still not really expiration dates, but an assurance that the product will meet its nutritional standards (some nutrients can be lost in storage) and its quality standards. Some states have their own dating requirements.
If a date is shown, there must be an explanation for the date immediately adjacent to it. Such as sell by or use before. Notice that neither of these says not safe to consume or even expiration. They are suggestions. You are more likely to find an unrecognizable code on canned foods and other shelf-stable goods, whereas you are more will find a recognizable date on perishable goods like meat, poultry, eggs, and dairy products.
Sell-By, Use-By, Etc.
- Sell-By is for the store. It tells them how long to keep the food on the shelf, and helps with rotating of stock. In general, you should try to buy cans that are not past their sell-by date, to ensure the highest quality, and the longest shelf-life at home.
- Best if Used By just means that the product will have the best quality if used by, or before, this date. It is not a safety date and foods that are past their best if used by date should not be assumed to be dangerous.
- Use-By is the date that the manufacturer has determined to be the last date that you can expect the product to be at peak quality. Meaning absolutely as good as the day it was canned. A food well past this date can still be quite good quality.
- Closed or coded dates are packing numbers, as explained above, for use by the manufacturer.
The most important thing to realize about all these dating methods, and all label dates in the U.S. is that they are meant to indicate quality, not safety. Even perishable foods can still be safe after they pass their "expiration" date. Confusion over these dates cause a great deal of food waste!
The Condition of the Can Is More Important
Much more important than the date on the bottom of a can is the condition of the can! If a can is dented, bulging, rusty or corroded, or shows any other signs of damage you should avoid using it. Also, if you open the can and a lot of pressure is released, such as you hear a lot of hissing, do NOT eat the food. Throw it out! Any and all of these things could be a sign of potential contamination and particularly the growth of botulinum responsible for botulism poisoning. I hope I don't have to tell you that if food is actually seeping from the cans, you should not use it.
Obviously, if the food looks moldy or has little white cloudy strands in it, you should not eat it. Any type of "cloudy" appearance is generally bad. If it smells bad don't eat it.
Conclusion: Can You Eat Expired Canned Foods?
So, the short answer is, yes, you can eat canned foods that have expired, because the 'expiration date' is not an expiration date at all, but simply a best-by date or a sell-by date. The date on the bottom of most canned foods is therefore not something with which you need to concern yourself. Remember that acidic foods will not last as long as other foods and that shelf-stable dairy products will not last nearly as long as vegetables or meat. Let the appearance, your nose, and the taste of the food be your guide, but remember that the kinds of pathogens that cause food poisoning are not the same kinds of bacteria that are responsible for the smell of foods going bad.
Throw away damaged or otherwise questionable cans. You've probably said to yourself many times, after opening an old can, "it seems fine." Well, that's usually because it is fine, especially if "fine" means safe. On the other hand, some folks will tell you "canned foods last forever." Nothing lasts forever, especially food, but canned foods can last a mighty long time.
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