Canned products are made by a series of processes including raw material pretreatment, canning, exhaust, sealing, sterilization and cooling.
In order to be made into a canned food, it must to have a container that can be sealed (including a soft bag made of composite film). And must go through the four processes of exhaust, sealing, sterilization and cooling. In theory, the productive process must be made to kill pathogenic bacteria, spoilage bacteria, toadstools, and to inactivate enzymes.
The most common canned foods are:
1. Canned meat, such as canned braised pork, canned braised beef, canned tuna, etc.
2. Canned fruits, such as canned peaches, canned oranges, etc.
3. Canned vegetables, such as canned pickled cabbage, dried beans, etc.
No! The reason cans can last a year, a half or even a few years is not because of preservatives, but because of the process. Canned food raw materials should be sterilized first, and then put into a aseptic tank, sealing while hot, after cooling, the pressure in the tank will cause the bottle mouth to be tighter (thermal expansion and cold contraction principle), and the bacteria outside can’t get in; A can made strictly in this way will not spoil for two or three years without preservatives, so there is no need to add preservatives.
No! In fact, the can is usually made of sterilization treatment, and the heating temperature is not too high, generally not more than 150 degrees Celsius, can better ensure the nutrition of the can, and we cook at home, cooking temperature is easy to exceed 200 degrees Celsius.
The current state of the canned food industry
At present, canned food is no longer a simple substitute when the food supply is tight, enterprises strive to provide consumers with "home-cooked taste", so that canned food into three meals a day, including vegetables, fruits, meat, spices and so on.
Tinplate and glass cans used in the past are being replaced by more convenient and practical cans, aluminum two-piece shallow washing cans and plastic coated plates heated by microwave ovens.