The Canning Process
When properly done, the canning process puts the preserved food in the can that keeps it from contamination. During the canning process, the foods are placed in a container and heated to a temperature that kills microorganisms that spoil the food. This is done by driving the air out of the container. Then, a vacuum seal is made while it is cooling to prevent the air from getting back.
There are two safe canning methods- the boiling water bath method and pressure canning. In the boiling water bath method, they heat jars of food completely covered with boiling water
and cooked for a specified amount of time. This is safe for jellies, jams, tomatoes, fruits, and pickles. As early as 1920s, the production of toxins in canned goods by bacterial cells called Clostridium botulinum has been detected (Thompson & Tanner, 1925). However, can be killed by boiling but they form spores that withstand it. These spores can grow even without air and eventually form the poisonous botulinum.Risks behind the Safety of Canned Foods
Generally, canned foods are safe to eat. If canned foods were so dangerous, then they should have been banned from the market decades ago. However, there are still risks involved when we talk about canned foods. Since pregnant women are more prone to food poisoning, eating canned foods during pregnancy is not encouraged. While the canned foods are being packaged, unwanted substances might be included in the food causing some health risk. The risk, however, is not that great to totally ruin
one’s health. But that little risk may be accumulated and exacerbate if canned foods are taken regularly. Remember also that more risks are there in canned foods that are watery and acidic, oily, and heated such as oily, canned fish like canned sardines and salmon.Convenience and Safety of Canned Foods
Canned foods have an incredible shelf life. In fact, a can of veal produced in 1824 was found to be in perfect condition when opened in 1938, although 14-year can storage is not normally recommended. Moreover, salmon in canned foods contains the very healthful and rare omega-3 fats. Nutritionists believe that the health benefits of salmon outweigh its risks when canned. The least contaminated types of salmon then are recommended: the wild-caught Pacific salmon or organically farmed salmon. Also, avoid buying canned fish in vinyl-lined cans that has bisphenol-A or BPA. BPA can disrupt activities in the body's endocrine or hormonal system.
The Bottom Line
While canned foods are convenient and safe, the convenience of instant foods can never outweigh the benefits of their original form. Salmon sushi is still way more healthful than canned salmon.
References:
Hall, M.N. (1979) The shelf life of canned foods. Nutrition and Food Science, Volume 79 Issue 4, pp.2 - 5
Thompson, L. and Tanner, F. W. (1925). Toxin Production by Clostridium botulinum in Canned Foods. The Journal of Infectious Diseases. Volume 37, Number 4. pp. 344-352