A time-tested process
The first canned foods appeared in the 19th century, driven by the need to preserve food on long maritime expeditions. They revolutionised sailors’ diets and ended the problem of scurvy, thanks to the vitamin C partially preserved in the canned foods.
Today, canning technology allows us to preserve food and protect its nutritional quality for long periods at room temperature.
The process works by heating airtight cans to sterilize the food inside them, and it remains one of the most widespread and safest ways of preserving the health benefits of food.
Through the years this process continued to advance as research into the effects of heat treatment has improved our understanding, and the manufacturing process of tinplate cans has become more sophisticated.
In terms of safety, the process has stood the test of time. The modern packing industry is extremely well controlled and products and production facilities are subject to regular inspection, especially on a microbiological level. In the context of a risk analysis no case of botulism has been reported since 1918 among the 700 identified references. So, consumers can be confident about quality and safety when buying canned food.
One of the advantages of canning foodstuffs is that sterilization by heat does not modify the macronutrients – proteins, lipids and carbohydrates – of the canned food.
As a rule, vitamins are preserved at the rate of about 70% in canned products which is close to the content in fresh foods that have been stored for several days before eating (see diagram).
With modern farming, harvesting and packing practices, fruit and vegetables are canned very quickly after harvesting. Times of between two to four hours are common, thanks to the close proximity of many canneries to the cultivation areas.
This quick processing facilitates the preservation of most of the original organoleptic and nutritional qualities of the produce and limits the loss of water-soluble vitamins (C and Group B vitamins).
Similarly, many types of fish such as salmon, tuna and sardines are canned shortly after being caught. The process also preserves their beneficial nutrients such as Omega 3 fatty acids which are largely preserved by canning.