Most cans do not have preservatives added, and only a few cans may have a small amount of preservatives added due to process or raw material limitations. Canned food has a long shelf life, mainly determined by its manufacturing process. We still have a deep misunderstanding about many foods, such as canned food, which is convenient and delicious. The key is that the shelf life can last for 1-3 years. Most people believe that the longer the shelf life, the more preservatives there are. So it turned out that there were a lot of preservatives in the cans. After sterilization treatment, before sealing, the factory will exhaust the cans to ensure that the inside of the cans is in a vacuum state, making the cans have excellent sealing performance, which can effectively isolate the entry of external oxygen and prevent the growth of microorganisms in the food.