When Getting Canned is A Good Thing

This one is one of the most popular answers I have written on Quora, with some of the most views and, more importantly, some of the most up-votes.

The question dealt with canning and canned foods. It also, surprisingly, raised some controversial canning questions in the replies by other users.

The question was:

Are all canned foods cooked?

That answer to the question, “are all canned foods cooked,” is “kinda.”

They are definitely processed and the processing involves a preserving form of cooking. It is the definition of canning.

Canning is a way of preserving food so that the edible contents are processed and sealed in an airtight container in order to provide a stable shelf life that ranges from about one to five years, depending on the product and the process.

The canning process has been historically been used in many homes before home refrigeration was available. It was used in to preserve freshly harvested foods before they spoil. One way they were prepared was the food was placed into extremely clean jars and lids and boiled to kill off pathogens.

As they cooled, the jar lids formed a vacuum seal which allowed the foods to be stored without any unwanted forms of life eating the food themselves.

John Landis Mason made a fortune off of the process by inventing the Mason Jar.

That processing is a form of cooking.

But, there are also other methods of processing for preserving such as freeze-dried canning. The freeze drying process is not a traditional form of cooking but the results are edible so it counts as a preserving method.

The development of the sealed metal can has made a whole variety of foods eligible for preserving and long-term storage. They replaced fragile glass bottles and were developed to the point where cans are made strong enough to withstand high temperatures so that the foods are packed in the cans first and then cooked inside the can and all. If they hit the right temperature, there’s no need to worry about cross-contamination during the sealing process.

It’s not perfect. Sometimes, no matter which canning technique is used, some pathogens will survive and use the food to breed and grow until the can bulges and eventually explodes. Botulism and its toxins (the same toxin that’s used in Botox cosmetic surgery) can be deadly.

When I worked for a cannery, I saw this in action. When the product was canned diced tomatoes, it made a spectacularly gory sight. It sprayed everywhere and if the can was at the top of a pallet, it would drip down to the cans below.

This brings me to another important point about cans being cooked. Keep in mind that when you use a can opener, you are puncturing the seal. Whatever particles were on top of the can or on your can opener may now be inside the can. That can be dangerous and reverse the benefits of cooking.

As someone who saw the occasional rat and other critters scurry atop a stack of cans, I always recommend washing the can tops before opening them.

Here are a few fun canned food bits of trivia:

1) The sealed can was invented long before the can opener. You’d think they would have evolved together but troops in the field were supposed to use their bayonets or hammers to break open the can. If you are ever without a can opener, you can place the can with the lid side down over some rough concrete and rub and rub and rub until the seal is worn away and the can will pop right open.

2) If you look at the codes printed on the bottom of canned foo,d they tell a lot about the manufacturing process. If you look at two identical cans of foods but from different brands but find the same codes, that tells you that one producer made both cans but stuck different labels on them. It happens all the time. You can also tell this by reading the fine print on the label that says something like, “packed by ABC Growers and Canners.” No matter whose name is on the label, that’s the company that actually made them.

3) Back in 1974, samples of over 100-year-old canned food from the sunken wreck of the Bertrand, a steamboat carrying supplies that sank in the Missouri River in 1865, were tested by the National Food Processors Association. Although appearance, smell and vitamin content had deteriorated, there was no trace of microbial growth and the 109-year-old food was determined to be still safe to eat, although there is no record of anybody trying it.