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A video demonstrating the canning process, how it works and why it's important.

In this video, we show you how one of the most common food processing technologies is carried out – preserving food in metal cans.

Tinned tomatoes

Tinned or canned tomatoes are a staple item in many kitchen cupboards. All canned tomatoes are one of two tomato varieties: standard garden vine tomatoes and plum tomatoes, both of which are peeled before canning in juice or purée. The structural strength of plum tomatoes makes them ideal for canning. They are meaty and contain less juice and fewer seeds, which means they maintain their shape in the can. Garden vine tomatoes function nearly as well but have a different flavour profile and a different shape. All canned tomatoes are cooked in the can during the sterilization process, which ensures their safety and long shelf life. One drawback of canned tomatoes is that with prolonged exposure to the aluminium of the can, the acid from the tomatoes interacts to cause tomatoes to adopt a ‘tinny’ taste. This can be avoided by coating of the inside of the can to prevent direct contact. This used to be mainly through use of an epoxy resin, but these coatings contained bisphenols, including bisphenol A (BPA), which was linked to health concerns. Food can linings are now typically made from acrylic and polyester.

tomato canning process in 8 illustrated steps: picking (hand holding a tomato), transporting (lorry carrying a load of boxes of tomatoes), grading and sorting (3 tomatoes of different sizes and shapes, 2 are crossed as unacceptable and 1 ticked as acceptable), washing (tomato with water droplets), peeling (conveyor belt showing tomatoes entering a machine and emerging peeled), packaging (tin labelled 65% tomatoes, 35% tomato juice), pasteurisation (tomato can with a thermometer reading 98 degrees Celsius), cooling (box of cans of tomatoes and a thermometer reading 35 degrees Celsius)

The journey to canned tomatoes. ©EUFIC Source
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How Food is Made. Understanding Food Processing Technologies

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